US20100062844A1

US20100062844A1 - Authentication and validation systems for gaming devices

Info

Publication number: US20100062844A1
Application number: US12/619,639
Authority: US
Inventors: Robert W. Crowder, Jr.; Anand Singh; Anthony E. Green; Thomas E. Buckeyne; Pravinkumar Patel; Ronald A. Cadima
Original assignee: Bally Gaming Inc
Current assignee: LNW Gaming Inc
Priority date: 2003-03-05
Filing date: 2009-11-16
Publication date: 2010-03-11
Also published as: WO2011059905A1

Abstract

Systems and methods for authenticating and validating a device are disclosed herein. In one method, a manifest file is created for a gaming component, wherein the manifest file includes contents of each file from the gaming component. A digital signature is generated for each file from the gaming component, wherein the digital signature is created by using the contents of each file. Each digital signature is saved with each file in the manifest file. A digital signature calculation is performed on a file accessed during a bootup process. The contents of the accessed file are validated by comparing the calculated digital signature to the saved digital signature, and an error message is presented on a video display when the contents of the accessed file is not validated.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. application Ser. No. 11/423,370, entitled AUTHENTICATION AND VALIDATION SYSTEMS FOR GAMING MACHINES, filed Jun. 9, 2006, which is a continuation-in-part of U.S. application Ser. No. 10/794,760, entitled GAMING SYSTEM ARCHITECTURE WITH MULTIPLE PROCESSES AND MEDIA STORAGE, filed Mar. 5, 2004, which claims the benefit of U.S. Provisional Application Ser. No. 60/452,407, entitled GAMING BOARD SET AND GAMING KERNEL FOR GAME CABINETS, filed Mar. 5, 2003, all of which are hereby incorporated by reference in their entirety.

COPYRIGHT NOTICE

A portion of the disclosure of this patent document contains material that is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent files or records, but otherwise reserves all copyright rights whatsoever.

FIELD

Systems and methods for authenticating and validating components of a computerized device, such as a gaming machine or other electronic device, are disclosed herein.

BACKGROUND

In previous systems, authentication of content on read/write media or non-secured media storage involves calculating a hash value over the data contents and then using the hash value in conjunction with a digital signature and public key to verify that the data contents are authentic.
Typically there is a secure memory, or read only sealed memory, such as an EPROM which contains the authentication algorithm. Additionally there is non-secure media that contains the content to be authenticated. The secure memory can be removed and independently verified with external devices; however data in non-secure device cannot be easily removed and verification is more difficult. Therefore, it is desirable to have a program that is running from the secure memory authenticate the contents of the non-secure device.
The authentication methods usually involve calculating a hash value over the entire contents of non-secure media, or major portions thereof, at boot time. The problem with this method is that it takes a considerable amount of processing time to calculate a hash value over the entire contents of the non-secure media, especially if it is a hard drive, CD-ROM, or DVD-ROM that contains a large amount of data. This results in considerably longer boot times for gaming machines and other devices that require verification. For example, some boot times are as long as ten minutes or more. As gaming machines and other devices become more sophisticated, the storage requirements for the non-secure media is growing, resulting in even longer durations for boot time authentication.
Moreover, in many gaming jurisdictions, there are regulatory requirements that mandate that authentication of a system be performed by a program running from the secure media. For gaming machines based on personal computer (PC) architecture, this typically means that the BIOS must reside on the EPROM and the authentication code executed from the BIOS EPROM. This puts a further limitation on gaming machines because authentication code executing from the BIOS EPROM may not run as quickly as code executing from the faster PC-based RAM.
An alternative to the above method is to have the BIOS authenticate the operating system only, load the operating system, and then have the operating system authenticate the remainder of the non-secure media. However, this method still increases the boot time because the entire content of the non-secure media is authenticated by the operating system at boot time.
Additionally, regulatory gaming jurisdictions require that the contents of the non-secure media, and contents of programs executing from volatile memory, be checked on a periodic basis, or whenever significant events occur. For example, when a main door closes, the gaming machine must make sure that all code executing from RAM is authentic and that such code has not been modified. Some gaming machines have handled this requirement by re-authenticating the programs on the non-secure media and reloading them into RAM for execution. These requirements further contribute to significant delays that occur due to complying with authentication regulations.
Furthermore, it is possible to download data from a central host on the network to the non-secure media. It is desirable to have the ability to download individual files or groups of files to change the capabilities of the gaming machine. This may involve downloading a new game for use by the player or downloading some enhancement to the operating system files. Nevertheless, if there is just one digital signature for the entire contents of the non-secure media device, then updating small portions of the contents through downloading becomes more difficult because the host must also download the new digital signature. This means the host needs to re-sign the contents prior to download. Such a process has its drawbacks because the host may not be secure if it is in a casino location and not controlled by the gaming manufacturer that produced the code.
Accordingly, there is a need for systems and methods to authenticate and validate files on gaming devices.

SUMMARY

According to one embodiment, a means of quickly authenticating the contents of one or more manifests located on a writeable media device is disclosed. Once the contents of one or more manifests are authenticated, the boot process of the operating system is begun. The operating system then calculates a hash value over each component on the writeable media, as it is needed, and then compares it to a corresponding hash value located within the manifest to insure that the component has not changed. One benefit of this embodiment is that the digital signatures that are used for authentication are only calculated for the data located within the manifests, which are relatively small in size when compared to the entire data set of the writable media. Another benefit is that, for verification, a hash is performed on the components and compared to an associated manifest value, whereby the calculation of the hash is computationally less intensive than performing a digital signature check, as is preformed on the manifest.
According to another embodiment, the components are verified on an as-needed basis, allowing for quicker boot times because only the components that are loaded are verified. This results in quicker system loading times, and through definition of the manifest components, better control over what components are verified and when they such components are verified.
Several methods of organizing the components are available. In one embodiment, a component is verified as or within partitions on the hard disk device. For example, in one embodiment, the hard disk device contains multiple partitions containing, for example, the Linux operating system, gaming libraries and executables, and multiple games with each game being placed within a separate partition. During boot up, the manifest for the partitions is authenticated using DSA signature validation, and then each partition is verified when it is mounted or loaded by the operating system. Such verification is performed by calculating the hash value over the partition as it is mounted, and comparing it to the hash located within the manifest file. This allows the operating system to boot quickly because just the operating system is verified prior to loading the operating system. Then the libraries are verified and loaded. Only the games that are active need to have their respective partitions verified and loaded, although, optionally, several game files can be loaded at once for anticipated play. For example, and not by way of limitation, if a hard drive has 100 game partitions, but only 10 games are active, then only the 10 game partitions of the active games need to be verified at boot time.
In another embodiment, components are broken down into files, where the manifest contains an entry for each file in the partition. During boot time, the BIOS verified the Linux kernel boot image, and loads it. The Linux kernel verifies each file as it is opened. The added benefit is that an entire partition does not need to be verified when it is mounted. Instead, the files in the partition are verified as they are opened. If the operating system only needs to load 20% of the files during boot time, then the remaining 80% of the files can be verified on an “as-needed” basis when they are loaded at a later time. This dramatically decreases the boot time for the gaming machine. Likewise, games are able to load just a portion of their graphic files during boot time. The remaining graphic files used for animated bonus screens, movies, and sounds can be loaded later as those resources are required throughout the game play cycle. In this regard, if a game contains 512 MB of graphics (by way of example only), 80% of which are sounds and movies, then the load time for the game is dramatically improved by delaying the loading of large files to support those sounds and movies.
Still, further methods of separation of the components to be verified are possible. For example, and not by way of limitation, games that play a 100 MB movie typically open the file and stream the content of the file to the display as the movie is being played. Therefore, it is not desirable to verify the entire file when it is opened, as there would be a significant delay when the movie file is opened for streaming. Therefore, another embodiment allows files to be broken down into blocks of data where each block is verified as it is read from the media. For example, the manifest file may contain a file entry for a 100 MB file, where the file is broken down (by way of example, and not by way of limitation) into 4K block sizes where each block includes a corresponding hash value within the manifest file entry. As each block of the file is read, only that particular block needs to be verified before loading. This allows games to stream large sound and graphic files directly from the hard drive while simultaneously verifying the contents. The benefit is file verification without delays perceived by the player.
In another embodiment, the breakdown of components is by sectors on the hard disk device. In this embodiment, each sector on the hard drive has a corresponding entry within the manifest. Since sectors are organized around the geometry of the hard drive, and not the file system, this embodiment results in a more efficient and simpler method of verifying information as it is loaded. For example, the Linux operating system has a block driver for a hard drive. When a block driver is instructed to load blocks of data for use by the file system, the block driver can read the sectors of the disk for the blocks of data and verify each sector as it is loaded. The benefit to this process is that sectors comprise continuous data on the hard drive organized around cylinders. Sectors are loaded very efficiently by the hard drive and thus can be efficiently verified using this mechanism. If an entire image is downloaded from a host server for a partition, each partition contains the files in a predefined organization. In one embodiment, a manifest for sectors is pre-calculated for the partition and downloaded along with the partition image.
In another embodiment, when files are downloaded and installed by the gaming machine, the manifest is calculated dynamically by the gaming machine and stored in a writable area. Once the manifest is created based on any of the component breakdown methods described above, they are digitally signed by the gaming machine itself, or by a remote server. This allows for greater flexibility in how the component breakdowns are selected to achieve the greatest verification efficiency. For example, in one embodiment, downloaded files found in a partition allow the gaming machine to dynamically create a manifest based on hard drive sector verification that is digitally signed by the gaming machine, or by a remote host during manifest file creation. This embodiment provides individual file download capabilities, while maintaining the sector-based verification aspect, which may be the most efficient for the hard disk device in some embodiments.
In one embodiment, a hard disk device contains a manifest partition, where the manifest files can be quickly located and authenticated. Alternatively, in another embodiment, the manifest files are contained in a predefined section of the hard drive reserved for quick loading and verification. In another embodiment, the entries of the manifest are spread out over the entire file system. For example, in one embodiment, the hash value for a file is appended to each file, or in each file's directory entry. The digital signature is calculated over all, or logical groups, of the manifest entries spread out over the file system.
In one embodiment, manifests are broken down to include entries for logical groupings of files. It is preferable in some gaming jurisdictions to have regulatory agencies approve groups of files as a package. For example, but not by way of limitation, in one embodiment, game files are broken down into several groups of files relating to: 1) paytable and win evaluation, 2) game executable code, 3) basic game graphics and sounds, and 4) paytable graphics and sounds. Each group of files is configured to be updated or replaced with a corresponding group of files. For example, to change the paytable, groups 1) and 4) are downloaded. Likewise, groups 2) and 3) are updated to change the look and feel of the game. Subsequently, as a particular group is downloaded, a corresponding manifest for the file group is also downloaded. This is referred to as a package. In one embodiment, a package can contain one or more manifests.
According to another embodiment, a method verifies a gaming component. The method includes determining if a manifest is authentic, the manifest including component information and a stored hash for the gaming component; performing a hash calculation on the component to produce a calculated hash if the manifest is authenticated; verifying the gaming component by comparing the calculated hash to the stored hash; and loading the gaming component if the calculated hash and the stored hash are equal.
In one embodiment, the component comprises a data file. In another embodiment, the component comprises a data component stored in a partition of a digital storage medium. In this embodiment, the stored hash is a hash of the entire partition, and performing the hash calculation includes performing the hash calculation on the entire partition if the partition has not yet been verified during operation of the device.
In yet another embodiment, the component comprises a data component stored in a library located on a digital storage medium. In this embodiment, the stored hash is a hash of the entire library. The performing of the hash calculation comprises performing the hash calculation on the entire library if the library has not yet been verified during operation of the device.
Yet another embodiment includes a method of verifying one or more components in a device. The method includes determining if a manifest is authentic, the manifest including component information and a stored hash for each component; performing a hash calculation on each component as each component is needed for operation of the device to produce a calculated hash for each component if the manifest is authenticated; comparing the calculated hash to the stored hash for each component; for each component needed for operation of the device, loading the component if the calculated hash and the stored hash are equal.
In another embodiment, a method verifies a component, wherein the component has a plurality of sub-components. The method includes determining if a manifest is authentic, the manifest including sub-component information and a stored hash for each sub-component; performing a hash calculation on at least one sub-component to produce a calculated hash if the manifest is authenticated; verifying the at least one sub-component by comparing the calculated hash to the stored hash for the sub-component; and loading the sub-component if the calculated hash and the stored hash for the sub-component are equal.
In yet another embodiment, a system is used to verify a component. The system includes a processor, and a set of instructions that are executable on the processor for authenticating a manifest, wherein the manifest includes component information and a stored hash for the component. Included is a set of instructions that are executable on the processor for determining if the manifest is authenticated. Further included is a set of instructions executable on the processor for performing a hash calculation on the component to produce a calculated hash if the manifest is authenticated. A further set of instructions is executable on the processor for verifying the component by comparing the calculated hash to the stored hash. A further set of instructions that is executable on the processor is included for loading the component if the calculated hash and the stored hash are equal.
In another embodiment, a system for verifying a component includes a computer usable medium having computer readable program code embodied therein configured for verifying a component. Computer readable code configured to determine if a manifest is authentic is included. The manifest includes component information and a stored hash for the component. Further computer readable code is configured to perform a hash calculation on the component to produce a calculated hash if the manifest is authenticated. Further computer readable code is configured to verify the component by comparing the calculated hash to the stored hash. Further computer readable code is configured to load the component if the calculated hash and the stored hash are equal.
In another embodiment, a method verifies one or more files stored on a network associated storage device connected to a network. The method includes determining if a manifest is authentic, the manifest including component information and a stored hash for a file; reading the file from the network associated storage device over a network connection if the manifest is authentic; performing a hash calculation on the file to produce a calculated hash; verifying the file by comparing the calculated hash to the stored hash; and loading the file if the calculated hash and the stored hash are equal. In one aspect of this embodiment, the gaming machine uses a plurality of files stored on the network associated storage device, reading the file, performing the hash calculation, verifying the file, and loading the file are performed for each file, as needed. In another aspect of this embodiment, verifying the file includes performing a SHA-1 verification. In another aspect of this embodiment, the network associated storage device comprises a network attached storage device.
In another embodiment, a method verifies one or more files stored on a diskless storage device. The method includes determining if a manifest is authentic, the manifest including component information and a stored hash for a file; reading the file from the diskless storage device if the manifest is authentic; performing a hash calculation on the file to produce a calculated hash; verifying the file by comparing the calculated hash to the stored hash; and loading the file if the calculated hash and the stored hash are equal. In one embodiment, the diskless storage device comprises a solid-state storage device. In another embodiment, the solid-state storage device comprises an erasable programmable read-only memory. In another embodiment, the solid-state storage device comprises a safe random access memory.
In yet another embodiment, a method verifies one or more files stored on a gaming component. The method includes creating a manifest file for a gaming component, wherein the manifest file includes contents of each file from the gaming component; generating a digital signature for each file from the gaming component, wherein the digital signature is created by using the contents of each file; saving each digital signature with each file in the manifest file; performing a digital signature calculation on a file accessed during a bootup process; validating the contents of the accessed file by comparing the calculated digital signature to the saved digital signature; and presenting an error message on a video display when the contents of the accessed file is not validated.
In yet another embodiment, a method verifies a gaming component. The method includes determining if the manifest is authentic, the manifest including component information and a stored digital signature for the gaming component; performing a digital signature calculation using the contents of the component to produce a calculated digital signature if the manifest is authentic; verifying the gaming component by comparing the calculated digital signature to the stored digital signature; and loading the gaming component if the calculated digital signature and the stored digital signature are equal.
In another embodiment, a method verifies a gaming component. The method includes identifying a validation protocol used to create a digital signature for a gaming component; determining if the manifest is authentic, the manifest including component information and a stored digital signature for the gaming component; performing a digital signature calculation using the contents of the component to produce a calculated digital signature; verifying the gaming component by comparing the calculated digital signature to the stored digital signature; and presenting an error message on a video display when the contents of the accessed file is not validated.
Other features and advantages of the claimed invention will become apparent from the following detailed description when taken in conjunction with the accompanying drawings, which illustrate, by way of example, the features of the claimed invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram that illustrates a device that comprises a gaming machine having components capable of verification according to one embodiment.

FIG. 2 is a block diagram that illustrates components of the gaming machine of FIG. 1.

FIG. 3 is a block diagram that illustrates directory and file organization of a partition for manifests on the hard disk device of FIG. 2.

FIG. 4 is a block diagram illustrating a structural organization of a manifest file according to one embodiment.

FIG. 5 shows a flow chart illustrating the steps for booting a BIOS and Linux operating system according to one embodiment.

FIG. 6 shows a flow diagram that illustrates the steps performed in a file verification method when a file is opened, according to one embodiment.

FIG. 7 is a block diagram of one embodiment of a processing environment in a gaming machine.

FIG. 8 is a flow diagram illustrating a method for creating a PVSSR manifest.

FIG. 9 is a block diagram of one embodiment of a BIOS EEPROM.

FIG. 10 illustrates block diagrams of hard disks and compact flashes used in the gaming device.

FIG. 11 illustrates one embodiment of a manifest partition.

FIG. 12 is a flow diagram illustrating a startup process for a gaming device.

FIG. 13 illustrates one embodiment of an In-Memory File Validation Table.

FIG. 14 is a flow diagram of a method for creating an In-Memory File Validation Table.

FIG. 15 illustrates another embodiment of an In-Memory File Validation Table.

FIG. 16 is a flow diagram of one method for validating a file on a gaming device.

FIG. 17 is a flow diagram of a start-up process for a gaming device.

FIG. 18 is a flow diagram of one method for running a background validation process.

DETAILED DESCRIPTION

In one embodiment, a system and method that uses digital signature technology to authenticate the contents of one or more manifests on a digital storage device is provided. Each manifest includes a list of file records, wherein each record contains the name of a file stored on the hard disk device, and a hash value derived from the contents of the file of a device. At boot time, the gaming machine first authenticates the contents of the manifest and then verifies the contents of the files using the hash value stored in the manifest. By way of example, but not by way of limitation, files are verified using a SHA-1 as they are needed during the boot up of the operating system and throughout normal operation. This method reduces the boot time of, for example, of a gaming machine and eliminates the need to check digital signatures for each individual file or over the entire contents of a non-secure media.
Referring now to the drawings, wherein like references numerals denote like or corresponding parts throughout the drawings and, more particularly, to FIGS. 1-6, there is shown one embodiment of an improved authentication system in accordance with the invention. With reference to FIG. 1, a block diagram illustrates a device 10 that comprises a gaming machine 10. A cabinet 130 houses the gaming machine 10 that has one or more CRT-type displays 134 for displaying game play. Electronic components 50 that operate the games on the gaming machine 10 are located within the cabinet 130.
With reference to FIG. 2, a block diagram illustrates components 50 of the gaming machine 10 capable of verification before and during use of the gaming machine 10. The components 50 comprise, for example, and not by way of limitation, software or data file components, firmware components, hardware components, or structural components of the gaming machine 10. These components include, without limitation, one or more processors 60, a hard disk device 100, volatile storage media such as random access memories (RAMs) 76, read-only memories (ROMs) 77 or electrically erasable programmable ROMs (EEPROMS) such as basic input/output systems (BIOS) 64.
In one embodiment, components 50 also include data files (which are any collections of data, including executable programs in binary or script form, and the information those programs operate upon), gaming machine cabinets (housings) 130, cathode ray tubes (CRTs) 134, or compact disk read only memory (CDROM) or CD read-write (CR-RW) storage. In one embodiment, the data files may include data storage files, software program files, operating system files, and file allocation tables or structures. Ports 139 are be included with the gaming machine 10 for connection to diagnostic systems 140 and other input/output devices 142. In one embodiment, the ports 139 each comprise a serial port, universal serial bus (USB) port, parallel port or any other type of known port, including a wireless port. Preferably, each of the components 50 have embedded or loaded in them identification numbers or strings that can be accessed by the processor 60, including the processor 60 itself, which are utilized for verification as explained below. In embodiment, the components that are data files each use their file path and name as their identification number or string.
Either within the gaming machine 10, or in the diagnostic system 140 attachable to the gaming machine 10, are executable instructions or a software program 70 for verification of the components (verification software 70), which may itself be one of the components 50 to verify if it is internal to the gaming machine 10. In one embodiment, verification software 70 is stored on a persistent storage media such as the hard disk device 90, ROM 77, EEPROM 64, in a complementary metal oxide semiconductor memory (CMOS) 72, in safe ram comprising a battery-backed static random access memory (BBRAM) 62, in flash memory components 150, 160, or other type of persistent memory. In one embodiment, the verification software 70 is stored in a basic input/output system (BIOS) 64 device or chip. BIOS chips 64 have been used for storing prior verification software, such as previous versions of the BIOS+chip used by Bally Gaming Systems, Inc. of Las Vegas, Nev. in their EVO gaming system. Placing the verification software 70 in the BIOS 64 is advantages because the code in the BIOS 64 is usually the first code executed upon boot or start-up of the gaming machine 10, making it hard to bypass the verification process. Alternatively, in one embodiment, the verification software 70 is stored in a firmware hub (FWH), such as Intel's 82802 FWH.
The organization of the hard disk device 100, and compact flash 150 and 160 for the operating system and game according to one embodiment are shown. The hard disk device 100 is broken down into partitions 110 to reserve a fixed amount of space for major components of the gaming system. When a hard disk device 100 is used as the mass storage media, all content is downloaded to the hard disk device 100 and there is typically no need for compact flash components 150, 160. However, in one embodiment, a hard disk drive 100 is used in combination with a game compact flash 160 containing game files, such files being previously approved by a regulatory agency. Preferably, in a completely downloadable system, the hard disk device 100 contains all files for the system and the game compact flash storage media 160 is not required. For jurisdictions that don't allow for hard disk devices, the operating system's compact flash 150 is used to hold the Linux operating system and gaming operating system related files, and the game compact flash 160 holds the game files.
Each storage media, including the hard disk device 100, and flash memories 150 and 160, is formatted into a typical disk drive geometry of sectors, cylinders and heads. Sector 0 of the storage media contains the master boot record, which also contains a partition table. In one embodiment, a /manifests partition 110 a is an EXT2 Linux file system that is designed to hold the manifest files that are associated with other files stored on the remaining media partitions.
An /os1 partition 110 b holds the root file system for the operating system that is mounted by a Linux kernel. The root file system contains the Linux operating system files as well as other utility files of the gaming machine that are needed for proper operation. It also contains the files that pertain to the operation of the gaming OS. These are programs specifically developed to manage the resources that are common to gaming machines, such as input/output (I/O), peripherals, random number generator(s), host communications drivers, and the like.
An /os2 partition 110 c holds the same type of files as the /os1 partition 110 b, but the /os2 partition 110 c includes an alternative operating system that can be executed. If for some reason the operating system contained in the /os1 partition 110 b fails to load and properly execute, then the system can revert to the operating system in the /os2 partition 110 c as a backup operating system. In one embodiment, the /os2 partition 110 c holds an operating system that was previously known to operate without failure. The operating systems contained in the /os1 and / os2 partitions 110 b, 110 c can be used interchangeably in an alternating fashion so that it can be guaranteed that the last known, acceptable operating system can be executed if the other operating system fails to load. Another advantage of these dual operating system partitions is to allow for robust updates of the operating system, even if a power-fail should occur during package installation. This is particularly important for various remote system locations, where it may be inconvenient to send technicians to fix failed downloaded updates.
In another embodiment, a /download partition 110 d holds a writable partition where newly downloaded packages are stored and download log files are kept. When a package is installed, the package contents are used to update files on the hard-drive partitions as dictated by the package contents.
In a still further embodiment, a /games partition 110 e holds the files related to a game application. This includes the game executable, graphics, sounds, paytables, configuration and other files required for the game application to operate properly. In one embodiment, this partition holds files for a plurality of games and their associated files. This allows the system to support multigame applications.
The operating system's compact flash 150 layout is similar to the hard disk device 100 layout, except, in some embodiments, it does not contain a /games partition. The game compact flash 160 contains a /manifest partition and /game partition. The operating system compact flash 150 is used along with the game flash 160 to form a complete bootable system. The /manifests partition located on each media 160 contains the manifest files associated with their respective media partitions.
As alternative, instead of, or in conjunction with, the hard disk device 100, another mass storage device is used, such as a CD-ROM, CD-RW device, a WORM device, a floppy disk device, a removable type of hard disk device, a ZIP disk device, a JAZZ disk device, a DVD device, a removable flash memory device, or a hard card type of hard disk device.
FIG. 3 is a block diagram that illustrates directory and file organization of the /manifest 110 a partition for a hard disk device 100. As shown in FIGS. 2 and 3, a /config directory 302 contains configuration files that the BIOS can use during the boot process, including known operating system boot tracking files boot.id and active.id. In one embodiment, a public-key.id file stores a public key for verifying the /config directory itself, or the whole manifest partition as a component. The /os1 directory 304 contains the manifest files pertaining to the operating system in /os1 partition 110 b. The /os2 directory 306 contains manifest files for the operating system in the /os2 partition 110 c. The /games directory 308 contains all manifest files for the /games partition 110 e. In one embodiment, manifest files end in “.mfst” which allows the BIOS to uniquely identify them as it parses through the file system.
Still further, a “/os1/kernel.mfst” manifest file contains an entry associated with the Linux kernel image that is stored on the /os1 partition 110 b at the location “/boot/kernel.image”. Likewise the “/os1/initrd.mfst” manifest file contains an entry associated with the /os1 partition file at the location “/boot/initrd.image” The “/os1/os.mfst” file contains entries for all other files on the /os1 partition 110 b.
FIG. 4 is a block diagram that illustrates the layout of a manifest file according to one embodiment. The manifest file contains header information followed by an entry for each file. The first component is the Manifest Digital Signature (MDS). The digital signature is created at a later time after the manifest is created. During manifest creation, the MDS is initially filled with zeros as a placeholder. The next field is the SHA-1 hash value. This hash value is calculated over the remainder of the manifest file data. The next field holds the version string of the manifest. Each manifest is uniquely identified by its file name. However, additional version information is also placed within the file. The Build Time Stamp field (BTS) contains the date and time when the manifest was created. In one embodiment, the date and time field is in Unix format. The Manifest File Entry Count (MFEC) field contains the number of file entries that directly follow this field.
Each file entry contains information to allow the Linux kernel to verify the contents of a file that exists on one of the partitions. The first field of the file entry is the name of the file. The file name is a variable length string that is terminated by a null character. The name of the file matches the path of the file to which it refers, as it exists on the Linux file system. For example, and not by way of limitation, a file in a game partition with the relative path, “/blazing7s/paytable,” relates to an entry of “/games/blazing7s/paytable” in the manifest because the game partition is mounted under the “/games” directory of the Linux file system.
Following the file name field is the type field, which stores the type of the referred file. The type can be “file” to indicate the SHA-1 is over the entire file contents. In another embodiment, the type field can be set to “block” to indicate that the file data is broken down into blocks of hashed data. Following the type field is a summary SHA-1 hash value that is computed over the remainder of the record's data. The block size field that follows indicates the size of each block of file data. The number of blocks in the file is the next field and it denotes how many SHA-1 hash values will follow. The remaining SHA-1 hash values in the file entry are the SHA-1 values for each sequential block of data of the file. The last SHA-1 in the list includes the hash value over the last block of file data. This last block could be less than the full block size in the event the file size is not an exact multiple of the block size.
The benefit of block type verification is that it allows each block of data to be verified as the content of the file is being read. For example, a media file may consist of a file size of 310,000,000 bytes, which is approximately 302 Mbytes in size. Loading this entire file into memory may be difficult or impractical for embedded systems having limited memory. Therefore, it is desirable to stream the media file to the video display and sound system by loading one piece of data at a time. Additionally, verifying the entire 302 Mbyte file before playing it, may cause the system to present a significant delay to the player. By using a block size of 4 Kbytes, for example, each block is read and the contents are verified one block at a time. This results in the 302 Mbyte file having 75684 blocks and 75684 SHA-1 values stored in the manifest file. The last block of data in the file contains the remaining 2432 bytes of data of the file and the last SHA-1 in the SHA-1 list is calculated for this last block of 2432 bytes of data.
FIG. 5, there is shown a flow chart illustrating the steps for booting a BIOS and Linux operating system according to one embodiment. The BIOS is the first program to start when the gaming machine is powered on. The BIOS is located in a 1 MByte EPROM. Of course, it will be appreciated that EPROMs of other capacities may also be used. The last 512 Kbytes of the EPROM includes the BIOS code. The first 512 Kbytes is used as startup code.
The BIOS first executes on power-up, step 400. In one embodiment, the BIOS initializes PC-based hardware and then executes a BIOS extension prior to booting from media. The BIOS extension generally resides in the lower half of the EPROM. In step 402, the BIOS extension first validates itself by calculating a Standard Hashing Algorithm 1 (SHA-1) over the entire 1 MByte BIOS EPROM. In step 404, if the calculated SHA-1 does not match the stored SHA-1 in the BIOS, then the EPROM is deem corrupt and execution stops at the validation error state, step 490. The validation error state displays a meaningful error message to an operator and prevents further booting of the gaming machine system. The gaming machine remains in this unplayable, faulted state until power is recycled or the device is turned off and on. Again, a SHA-1 is, but other techniques may also be used as are well know in the art.
The BIOS validation step 402 may also include the check of a digital signature. The digital signature and public key may be stored in the BIOS next to where the SHA-1 is stored. After the SHA-1 passes, the digital signature, public key, and SHA-1 value can be used by a digital signature algorithm to test the authenticity of the BIOS.
After the BIOS has authenticated the BIOS EPROM, in step 406, the BIOS authenticates the manifests on the media storage devices attached to the gaming system electronics. During initial boot-up, the BIOS searches for IDE drives connected to the electronics. One configuration includes one large capacity hard drive, although other configurations are used with other embodiments. For example, with reference back to FIG. 2, in one embodiment, the media storage device storing the files to be verified and used by the gaming machine 10 is a remote media storage device 101, that is accessed over a port 139 configured as a network connection (e.g., RJ 45 for TCP/IP network, USB, switched fabric connection, or the like) to a download server 122. The files are read from the remote storage device over the network connection port 139 from the download server 122.
In another embodiment, the remote media storage device 101 is combined with the download server 122 in a specialized file server called a network file storage device. A network file storage device contains a slimmed-down operating system and a file system. The operating system processes I/O requests by supporting common file sharing protocols. In one embodiment, this allows the gaming machine 10 to operate as a diskless workstation, and boot directly from the remote media storage device 101.
In yet another embodiment, the media storage device storing the files to be verified and used by the gaming machine is a solid state, or diskless, storage device, such as an erasable programmable ROM (EEPROM), safe random access memory (safe-RAM), another flash memory device, or the like.
Whether remote or local, hard disk or solid state, for each media storage device, the BIOS reads the manifests. In one embodiment, the manifests are read from a first partition 110 located on a hard disk device 100. In this embodiment, since the manifests are stored in a EXT2 Linux file system on the partition 110, the BIOS is programmed to read this file system so that it can open the root directory, subdirectories, and files within the subdirectories. The BIOS starts at the root directory for the manifest partition 110 a and performs a depth first recursive search for all manifest files that have the “.mfst” suffix. Every manifest file found is then authenticated by the BIOS.
In one embodiment, for each manifest file, the system first reads the size of the file from the directory entry. Then, in step 406, the BIOS opens the file to read the file contents in binary format. The first 20 bytes of data are read as the digital signature for the manifest. The next 20 bytes are read as the pre-calculated SHA-1 representing the entire remaining file contents. The BIOS then reads the remaining contents of the file and calculates a SHA-1 over those remaining contents. The pre-calculated SHA-1 and the calculated SHA-1 then are compared. If they are not equal values, then the BIOS provides a validation error and stops. Next, in step 406, the BIOS uses the SHA-1 value, the digital signature for the manifest, and the public key stored in the BIOS to authenticate the manifest file using a digital signature algorithm (DSA). In step 408, if the DSA passes, then the manifest is considered authentic; otherwise the BIOS provides a validation error and stops, step 490. The manifest being authenticated need not be loaded into memory. In one embodiment, it is read in a piecemeal manner so that the SHA-1 can be calculated over the file contents. Once a manifest is authenticated, then its contents are cleared from memory. The BIOS then proceeds to authenticate the next manifest.
Additionally, when authenticating manifest files, the BIOS keeps a running SHA-1 hash value over all manifest file data it processes in a global variable 410. Initially, this global variable, BIOS SHA-1, is set to zero. As each manifest is authenticated, the BIOS uses the BIOS SHA-1 result to perform a running calculation over the entire manifest file contents. The BIOS then stores the new BIOS SHA-1 result back in the global variable, step 409. This process is similar to a process of calculating a SHA-1 over all manifest files as if they were all concatenated into a stream of file data. Therefore, the order of processed manifests is kept consistent between the BIOS and the kernel.
The BIOS SHA-1 value is then passed to the Linux kernel when it boots, step 418. The Linux kernel can use it to guarantee that the manifest file contents are identical when the Linux kernel loads the manifests into memory. This allows the BIOS to perform all of the authentication from EPROM based code, but allows the Linux kernel to verify that every file loaded thereafter has not changed from its originally processed contents. This step guarantees that the manifest files have not been changed between the time the BIOS authenticates them and the time the Linux kernel loads them. In an alternative embodiment, the BIOS system continually accesses the hard disk device 100 for the manifests. With constant accesses and a quick boot time, the system can reduce the chance that the manifest file has changed.
Once all manifests are authenticated, step 412, then the BIOS verifies the Linux kernel image and the initial ram disk image, step 414. The Linux kernel image contains the compressed binary image for the Linux kernel. This is the first part of the Linux operating system that runs. The initial ram disk image contains a ram based file system that holds the startup drivers and startup scripts used by the Linux kernel image. In one embodiment, the manifest partition contains two special manifest files that can be identified by their file name. The /manifests/os1/kernel.mfst file contains the SHA-1 for the kernel image and the /manifests/initrd.mfst contains the SHA-1 for the initial ram disk image. When authenticating these two manifest files, the BIOS saves their embedded SHA-1 values to use when loading the Linux kernel image and the initial ram disk image. In step 414, the Linux kernel image is loaded into memory by the BIOS. As it is loaded, the BIOS calculates a SHA-1 over the contents. Once loaded, in step 416, the BIOS compares the calculated SHA-1 to the SHA-1 kept from the manifest file, kernel.mfst. If they are the same, then the Linux kernel image is verified. The BIOS performs the same type of operation on the Linux initial ram disk image. If either of the SHA-1 comparisons fail, the BIOS produces a validation error and halts further booting, step 490. Once both images are loaded, the BIOS jumps to the start of the Linux kernel image In-Memory, step 418, passing the BIOS SHA-1 manifest calculation it computed over all manifest files found on all media devices, step 410. This value is passed in as a startup value allowing Linux to use it later in the boot process.
When the Linux kernel executes, it performs some initialization, eventually mounts the initial ram disk image, and runs the startup scripts found on the initial ram disk, step 420. These startup scripts load certain drivers from the ram disk and install them into the Linux kernel. One of these drivers is the file verification module. This module intercepts file open calls made to the Linux kernel so that a file can be verified immediately upon opening and before use. The module is also responsible for storing the manifest entries of file names and SHA-1 values to use in file verification. After installing the file verification module, the startup scripts run the manifest loader that loads the manifests into the kernel file verification module, step 422.
The manifest loader begins searching for manifest files on the media devices. In one embodiment, the search for manifests is performed using the same method and order as did the BIOS. Similar to the BIOS, the manifest loader contains a global variable, Linux SHA-1, that it initializes to zero, step 422. As each manifest file is loaded, step 424, the SHA-1 is calculated over the entire manifest file contents. In step 426, each manifest is parsed based on the manifest file version, type information, and file type version information. The manifest loader parses out each file entry record. For each file entry it calls, the Linux kernel file verification module passes the file name, file type, file SHA-1, and any extra data associated with the file types, such a block list of SHA-1's. As each call is made to load a manifest entry, the file verification module adds each entry into an internal memory table protected by the kernel and that is inaccessible to other processes, step 424, until the last manifest is processed, step 428. This table is preferably a hash table keyed on file names to allow for quick lookups when a file is opened. It is possible for two manifests to reference the same file, but they both preferably contain the same SHA-1 value. In other words, duplicate entries are accepted and filtered out by the file verification module. In one embodiment, if the same file name is loaded into the kernel file verification module and the file has two different SHA-1 values, then such is considered a validation error and the boot process is terminated.
Once the manifest loader has loaded all manifests from all media devices, it then passes into the file verification module the Linux SHA-1 value it computed over all manifest file data. In step 430, the Linux kernel compares the BIOS SHA-1 passed to it when starting the Linux kernel to the Linux SHA-1 passed in by the manifest loader. If they are identical, then all manifests that have been authenticated by the BIOS have been loaded by the manifest loader and all manifest data was identical in both operations. In this case, the file verification module records that it has been properly initialized and the kernel call returns to the manifest loader to continue the boot process. If a mismatch between the BIOS SHA-1 and Linux SHA-1 is found in step 430, then the kernel goes into a file validation error mode and prevents further execution of the boot process in step 490.
During the boot process, startup scripts for the system continue to run, step 470. Each of these files is loaded and verified by the Linux kernel verification module by comparing its calculated SHA-1 value to the SHA-1 value loaded in step 424. Eventually the root file system for the operating system is mounted from the hard disk device. In one embodiment, it is mounted as a read-only file system. This file system contains more startup scripts to continue the initialization of the operating system and the eventual loading of the gaming operating system libraries, servers, and game applications that comprise the gaming system, step 480.
FIG. 6 is a flow diagram that illustrates the steps performed in file verification method when a file is opened, according to one embodiment. As each file is opened for processing, step 500, a standard file-open call is made to the Linux kernel, step 502. This can be caused by a script opening a file, a program opening a file, or a Linux library opening a file. Every file-open call is intercepted. In one embodiment, the Linux kernel is customized to check if the file is on a read-only partition, step 504, and if not, a function call is made through an indirect pointer to the file verification kernel module. Otherwise, the file does not need verification and the Linux kernel can open, step 506, and process, step 508, the file as it normally does.
More particularly, the kernel file verification module receives the call to verify a file, step 510. The system first looks up the file's complete path name in the hash lookup table loaded previously during the Linux boot process. In one embodiment, if the file entry is not found, then this unknown file cannot be verified and the Linux kernel goes into a file validation error mode, and prevents further execution of any applications. If the file is found, then it retrieves the SHA-1 value loaded for that file entry. The file data is then read by the kernel file verification module and a SHA-1 is calculated over the file contents, step 512. The SHA-1 calculated over the file contents is then compared to the manifest SHA-1 value retrieved from the hash table, step 514. If they match, then the file verification module returns to the Linux kernel allowing it to complete the normal file open process, step 506. If there is a mismatch, then the Linux kernel goes into the file validation error mode preventing further execution of any application processes, step 516.
In another embodiment, referring to the previous example of a 302 Mbyte file with “block” type validation, in an additional effort to save memory in the embedded system, the entire SHA-1 list for file-by-file type verification of files is not loaded at boot time. To save time, the Linux kernel retains In-Memory where the SHA-1 list of the 75684 SHA-1 values starts in the manifest file and uses it at a later time when the file is opened for streaming. When the file is opened, the Linux kernel reads the SHA-1 list from the manifest. In order to insure that the list has not changed or been corrupted, the first SHA-1 in the file entry is the SHA-1 hash value for the list. The Linux kernel can then load the list and check its SHA-1 against the SHA-1 originally loaded at boot time. Once this test is passed, then the file is ready for streaming and each block of file data can be checked as it is loaded.
In one embodiment, a more hierarchical organization of SHA-1 values is used. This organization allows the Linux kernel to load one piece of the SHA-1 value list at a time to further reduce any load or time delays. If the Linux kernel loads 1000 SHA-1 list values at a time, then a second tier level of 75 SHA-1 values are present. The first SHA-1 is computed over the 75 SHA-1 values. The first SHA-1 value in the second tier list is then computed over the first 1000 SHA-1 values of the 3rd tier.
By using different types of file entries as denoted by the type field, the manifest can support many different authentication methods. The BIOS does not need to retain information about the format for these types of manifests. The BIOS searches for manifest files ending in the “.mfst” extension, reads the contents, calculates the SHA-1 over the manifest file contents, excluding the first 40 bytes of the DSS and the SHA-1 values, and then compares the SHA-1 to what is stored in the manifest file. If there is a mismatch, then the manifest file is corrupt. If the SHA-1 values match, then the digital signature is checked with the SHA-1 value. If the digital signature passes, then the manifest is deemed authentic. If not, then there is a file validation error.
In other embodiments, the manifest is signed with other public/private key algorithms, such as RSA, without affecting the benefit that the digitally signed manifests provide. In one embodiment, the manifests are encrypted instead of being digitally signed. In yet another embodiment, the Linux Kernel Image and initial ram disk image are encrypted. The decryption key is stored in the BIOS. The BIOS decrypts the Linux kernel image and the initial ram disk image, and allows the Linux kernel to boot. By decrypting the kernel, the BIOS can run the kernel as a trusted program. The Linux kernel boots and the startup scripts run the manifest loader. The manifest loader decrypts the manifest files and loads the file entries into the Linux kernel file verification module, as described above. Once all manifests are loaded, the Linux operating system continues booting and dynamically checks the validity of each file as it is opened.
In another embodiment, manifests may be broken down to hold SHA-1's for files according to how software components are packaged and distributed. A package may consist of a set of files and the package manifest that controls or pertains to one aspect of the gaming machine's operation. By breaking the operating system or game files into smaller packages, a gaming system that supports download can have better control over which packages get updated when such update occurs.
In some embodiments, one manifest holds verification data for every file on the hard drive, while in other embodiments, the manifest is limited to only one file, wherein every file has its own associated manifest. Neither of these methods diminish the benefit of improving the boot speed, since the operating system verifies files that are loaded on an “as-needed” basis.
In another embodiment, one manifest with one digital signature is used for all data files on a gaming platform, or for a particular media storage device. In this embodiment, the manifest partition contains one manifest file and one digital signature. In another similar embodiment, the manifest partition is a list of files and their associated SHA-1 values, with a digital signature at the end of the partition, so that the entire partition is authenticated before loading.
The benefit to having one manifest is the simplicity of managing only one file entry list or one manifest, and the speed at which the manifest is processed. In some embodiments, the manifest is created at the time software is built for release. However, downloading one entire package to the hard drive along with its one associated manifest is not quite as beneficial as downloading individual packages, in some gaming jurisdictions. In these gaming jurisdictions, individual packages are created and approved by regulatory agencies in an independent manner. In gaming machines located within these jurisdictions, the packages are downloaded to gaming machines individually by a download server to form various configurations. This is much easier to manage instead of creating every configuration at the time the software is built and getting every combination of configuration approved by regulatory agencies. For these gaming machines, it is advantageous to include a manifest in or for each package downloaded.
In one embodiment, a method allows a single manifest to exist while still providing the ability to download individual packages. In this embodiment, the manifest is dynamically signed each time a new download occurs that affects the contents of the manifest. If a new package is downloaded that contains four new files and one changed file, then four manifest file entries are added and one entry updated with the new SHA-1 corresponding to the files. The gaming machine digitally signs the manifest after the download installation is completed. In this embodiment, the private key for digitally signing the manifest is located somewhere within the gaming machine.
In an alternative embodiment, the gaming machine, through a secure connection with a download host, sends the manifest information to the download host and the download host dynamically digitally signs the manifest and responds to the gaming machine with the manifest digital signature. In another embodiment, the host already has the manifest contents of the gaming machine and is able to digitally sign the new manifest and download it with the original download package. Either of these methods allows the download server to digitally sign the manifest so that the private key is not stored within the gaming machine. This added protection of the private key can be more easily performed on the download server and is more economical than placing the same protection on every gaming machine. Such protection can involve, for example, a secure computing system, chip, or plug-in board that provides digital signatures without compromising the private key.
As described above, the manifest contains file entries and their associated SHA-1 values. In an alternative embodiment, the manifest contains a list of partition entries that are on the storage media. Each partition entry indicates a partition on the hard drive and its corresponding SHA-1 value. The Linux kernel and the initial ram disk image are stored in a separate partition. The BIOS authenticates the manifest via its digital signature. It then verifies the Linux kernel partition by calculating a SHA-1 over the partition data, and then compares it to the manifest partition entry. Once verified, the BIOS loads the Linux kernel and the Linux kernel boot process begins. The manifest loader loads the manifest in the Linux kernel partition verification module. The partition verification module is responsible for verifying each partition as it is mounted by the Linux operating system. Partitions are larger than files, and verifying a partition prior to using some of the files in the partition may take a little longer than file based verification; however, it is still faster than verifying the entire media content prior to booting.
Another embodiment uses block-based verifying. Every fast access storage media in Linux is broken down into block-based accesses. Each block may be 512 bytes in size. Of course, any size block can be used. File systems are organizations that are built on top of the block based data access methods. In one embodiment, verification is built into the storage media by having a SHA-1 for every block of data on the hard drive. The manifest then becomes a list of SHA-1's for every block of data that is to be verified. Since many of the blocks of data on a hard drive may be identical, perhaps because they are unused, in one embodiment, the list is compressed to save space. In such a scenario, the manifest comprises approximately 20/512, or 4% of the disk space. If sequential blocks area used to form a larger block of 4096, or 4 Kbytes, of data, then the disk space required for the manifest reduces to approximately 0.5% of the disk space. With a 10 Gbyte hard drive, the manifest is approximately 50 Mbytes in size.
In another embodiment, using a method similar to that discussed above regarding file-based verification, hierarchical sections of SHA-1 values allow portions of the manifest list to be dynamically loaded on demand. For example, and not by way of limitation, the 50 Mbtytes list is comprised of 2,500,000 SHA-1 values. The list of SHA-1's is broken down into 25,000 sections, each section comprises 100 SHA-1 values. A higher level SHA-1 list of 25,000 SHA-1 values is used as the top level SHA-1 values, where each SHA-1 in this top level list is the SHA-1 over one of the 25,000 sections of SHA-1 values. This list is, therefore, about 500 Kbytes in size, which can easily be loaded into memory at boot time. When the operating system tries to read a block of data on the hard drive, the kernel determines which of the lower level 25,000 sections the block is associated. If this lower level section of 100 SHA-1 values is not In-Memory, then it is loaded. When the level is loaded, all 100 SHA-1 values for the section are read into memory and the SHA-1 over them is calculated. This SHA-1 must match its corresponding SHA-1 in the higher level list of 25,000 SHA-1 values. If they do match, then the loaded section of 100 SHA-1 values is verified, and the correct SHA-1 value for the block can then be used to verify the contents of the 4096 byte block that is then loaded.
In still another embodiment, sections of the SHA-1 lists and loaded are managed by a memory manager to determine when to release a section list to make room to load another section list on demand. Least recently used algorithms are used to determine which sections to discard. In one embodiment, by de-fragmenting a hard drive, even more efficiency is attained when using the block verification method across the entire hard drive.
When using manifests with file-based verification, it is possible to avoid loading all of the manifests. In one embodiment, the Linux system keeps In-Memory only the SHA-1 value for the manifest on initial loading, and then loads the remainder of the manifest on demand. For example, in one embodiment, when a particular partition is mounted by the Linux OS, then the Linux kernel loads the manifest that pertains to that partition. When the manifest is loaded, its contents are checked against the SHA-1 value that was loaded and stored in RAM during the boot process. This allows the manifest to be loaded after boot time to assure that it is authentic.
In another validation method, a manifest file approach using Pintsov-Vanstone Signature Scheme with Partial Message Recovery (PVSSR) is used for file validation. Instead of creating a SHA-1 on the contents of each file and then signing the SHA-1, a PVSSR signature is created using the contents of each file. As files are accessed, the PVSSR signature is used to authenticate the contents of the file before allowing it to be used. The PVSSR authentication system insures that modifiable and programmed components in the gaming device are authenticated during BIOS processing and before the Linux system starts. Additionally, the Linux OS code and the validation support code are contained on read-only EEPROM, thereby insuring code integrity once the EEPROM is burned.
As used herein, the initial RAM disk is an In-Memory logical disk used by the Linux kernel to load the support code when it is initializing the system and creating the environment under which the Linux system will run. The initial RAM disk is created using a compressed file that contains all the modules and programs needed to support initial system bootup. In the new file validation environment, the RAM Disk will contain the file validation module, the memory validation and the Faultdog module, as well as some hardware support modules needed to start the Linux support. The RAM disk will be stored as a compressed file on the BIOS ROM chip. Additionally, the terms disk, CompactFlash® and flash are used interchangeably within the document. These teens all refer to the media where files are stored on a gaming machine.
It should also be noted that reference is made to the Alpha Support Compact Flash (ASCF) and the Game Compact Flash (GCF). The Alpha Support Compact Flash contains all the files and executables needed to support the running of the Linux system and Alpha Game support Platform. This includes the Linux libraries and programs as well as the files and libraries used to support the running of a game. The Game Compact Flash contains all the files required to support and run a particular game.
FIG. 7 illustrates one embodiment of a processing environment in a gaming machine 10. The components above the dashed line 600 is stored on the socketted BIOS EPROM 602 in the gaming device 10.
Other components within the gaming device 10 include the Jurisdiction EPROM 604, the compact flashes 606, 608 containing the Alpha Game Environment support code and the game code, respectively, as well as the processing memory 610.
When the gaming device 10 is powered up, the BIOS 602 gains control and validates its contents using a CRC16 hash.
The Linux Kernel as well as the Validation and Fault manager modules are loaded from the BIOS into the EGM processing memory. The File Validation module 612 then reads and authenticates the contents of the Jurisdiction EPROM 604 as well as the contents of all the File Manifest files stored on the Alpha Support compact flash 606. If the Game compact flash 608 contains manifest files, these files are authenticated. Otherwise, the contents of the entire game flash 608 will be authenticated using a combination of a SHA-1 Hash and DSS signature.
Once this is completed, control is passed back to the Linux kernel to initialize the system operating environment and start the game. As each file on a read-only compact flash partition is accessed, the file's contents are authenticated using the appropriate authentication method (e.g., PVSSR or DSS). If the file being opened is covered by a DSS signed manifest file, then the SHA-1 value of the contents of the file is validated. A continuously running background process periodically authenticates the manifest files, the files they point to, and the contents of the Game compact flash.
Older game compact flashes that do not have a PVSSR or DSS manifest file associated with them are authenticated using the DSS signature for the SHA-1 value of the compact flash contents. This DSS signature is stored in the game flash's pre-partition area.
No access is allowed to the game flash until it has been authenticated.
After the initial authentication of the game flash's contents, its contents are continuously validated on a periodic basis.
If it is found that the contents are not valid, the machine is immediately halted.
Jurisdiction chips signed using older DSS technology have their contents authenticated using DSS signature of the Jurisdictions contents SHA-1 hash value stored in the Jurisdiction chip.
Generally, the PVSSR file validation methodology, disclosed herein, uses a manifest file approach and a PVSSR signature is created using the contents of each file. As files are accessed, the PVSSR signature is used to authenticate the contents of the file before allowing it to be used. The code to authenticate PVSSR signatures resides in a file validation loadable module contained within the initial RAM disk image that is stored on the BIOS EEPROM. The File Validation module also uses the Public Keys stored in the BIOS and a digital signature to verify: the contents of the file manifest files; the contents of the jurisdiction EPROM; and the contents of older game flashes that do not have PVSSR manifest files associated with them. The File Validation module also creates an In-Memory table of PVSSR signatures for all files on the read-only partitions of the Alpha Support and for the Game compact flash files if they exist.
If the Game compact Flash is covered by a DSS File Validation Manifest, then the SHA-1 hash values for the files contained on the game compact flash are read from the game DSS file validation manifest files and stored in a memory table for later access.
As shown in FIG. 7, the BIOS EEPROM also contains the Linux kernel module. Both file validation loadable module and the Linux kernel modules are loaded from the BIOS into the EGM main memory before the Alpha system is loaded and receives control. A CRC16 checksum is performed over the entire contents of the BIOS to insure that its contents are consistent and unchanged. When initialization is complete, control is passed to the Linux system initialization code to allow the system to start. As each file residing on a read only partition of the compact flash is opened, the file contents are authenticated using either the PVSSR signature or the SHA-1 hash value stored during the File Validation module initialization.
If the signature authentication fails or SHA-1 hash validation fails, the EGM will be halted with an error message and no further processing will be allowed.
Generally, one or more Validation Manifest Files (VMF) are created for file validation. In one embodiment, four VMF's are created for the Alpha Support Compact Flash: (1) Linux_base.ggmnfst which is a manifest file that contains all the files associated with the Alpha operating support; (2) Links_linux_base.ggmnfst which is a manifest that contains the information needed to validate that all logically-linked files point to the correct real file; (3) glass.ggmnfst which is a manifest of all the images that may be displayed on the gaming machine's top box video display; and (4) Links_glass.ggmnfst which is a manifest used to validate any logically linked files pointing to the correct real file.
For games using the PVSSR support, a minimum of two manifest files are used.
A first manifest is used for the actual game files, and a second manifest is used to validate that the logically-linked files point to the correct real file.
In one embodiment, each VMF header includes the information in the following table.


Field	Description

Signature	Length of PVSSR Signature
Length
PVSSR	Digital signature of the contents of the Manifest Header
Signature
File Count	No. of files referenced in the manifest
Time Stamp	Time stamp of when manifest was generated
Manifest ID	Unique identifier for the manifest
release id	Unique identifier for the release this manifest is
	associated with
Control Flags	Control flags on how manifest and its contents are
	processed
Signature File	For future use
Name
Reserved	2 KB of reserved space for use by download support.

After the VMF header, the VMF includes file entries for all the files to which the Validation Manifest File is applicable. Each file entry contains the following information:


Field	Description

PVSSR Signature	PVSSR Signature of the file contents
PVSSR Signature Size	Actual size of the PVSSR signature
Signature Block Offset	Reserved for future use
Signature Block Index	Reserved for future use
Check flag	Control flag of when and how to check PVSSR
	signature
Size of file's name	Size of the name of the file
File Name	Fully qualified file name for the signature

Generally, PVSSR signatures are created using Certicom-supplied hardware in a secured location with a public and private key pair only known to authorized individuals. Data to be signed is loaded into the signing system from a secure location, signed, and then stored back in the secure location.
FIG. 8 illustrates one method of creating manifest files having a PVSSR signature from an unsigned binary image of the Alpha Support or Game Compact Flash. At step 700, a list of all the files is extracted from the unsigned, compact flash image.
At step 702, the list is divided into a list containing all real files and associated data and a list containing the logical link file names that point to real file names. At step 704, the contents of each file from the real file list is read and passed to the Certicom signing hardware. A signature for the contents of each file is returned and saved in the manifest file at step 706. When all the files are signed, the entire contents of the real file manifest is signed at step 708. The returned signature is then stored in the manifest file header. For the logically-linked file list, the logical link name and the real file name are stored in the manifest file at step 710. The contents of the manifest file are then passed into the signing hardware and the resulting signature is saved in the manifest header at step 712.
FIG. 9 illustrates a layout of one embodiment of a BIOS EPROM 800 that supports PVSSR authentication. In this embodiment, the BIOS 800 includes the following: BIOS Initialization and Checksum 802; CRC16 of BIOS Contents 804; Linux Kernel Offset 806; Linux Kernel Size 808; Initial Ram Disk Offset 810; Initial Ram Disk Size 812; BIOS Flags 814; PVSSR Public Key 816; DSS Public Key 818; BALLY BIOS Extension code and loader 820; Linux Kernel Loadable Image 822; Initial RAM Disk Loadable Image 824; and Kontron® vendor BIOS Code 826. As those skilled in the art will appreciate, other embodiments of the BIOS EPROM may include fewer or more components.
The CRC16 hash is used to validate the contents of the BIOS. The BIOS initialization calculates a CRC16 hash of the BIOS contents and compares it to the stored CRC16 hash value. If the CRC16 has values that do not match, the system is prevented from starting. In one embodiment, an error message is presented on a display of the gaming device. The PVSSR Public Key is used by the file validation module to authenticate the PVSSR signatures for the files, jurisdiction EPROM, and compact flash.
The DSS Public key is used to authentic older versions of games and jurisdiction chips that were signed using the DSA/DSS signing process. The BALLY BIOS Extension code and loader provide the logic for copying the Linux Kernel and initial RAM disk from the BIOS into the system's main memory and then passing control to the Linux initialization code. The Kontron® vendor BIOS code performs initial hardware identification and setup.
FIG. 10 illustrates one embodiment of the partitioning of a hard disk 900, the OS compact flash 902, and the game compact flash 904. The reserved partitions 906 in the hard disk and OS compact flash 902 are dedicated to host download support. If the gaming device supports host download, the reserved partitions are formatted and initialized. Otherwise, these partitions 906 are not initialized and cannot be accessed. The os1 partition 908 of the OS compact flash 902 contains all files used to run the game and support the Linux System run environment. The glass partition 910 of the OS compact flash 902 contains the image files used for older style games running on a dual screen gaming device. The image file is used to display an image on the upper screen related to the game that is running on the gaming device. In a download environment, the reserved partition 3 (912) is designated as os2 and is used to save a copy of the last working version of the system support code.
FIG. 11 illustrates one embodiment of a manifest partition 1000 for an Alpha Support Compact Flash. The configuration directory 1010 includes a file called boot.id that is used to indicate which partition on the disk or compact flash boots the Linux system support. This is important in a download environment in which there is a primary and a backup OS (Alpha Support) partitions. The games directory 1012 is used to mount and link the manifest partition on the game compact flash. The os1 directory 1014 contains all of the manifest files associated with files stored on the Alpha Support Compact Flash. In a download supported environment, the os2 directory is available and contains the file validation manifest file for the backup Alpha OS support. The information contained within the os1 directory partition 1014 is only accessible by the File Validation Module's initialization process. The data extracted from the os1 partition 1014 is stored in a private reserved storage belonging to the File Validation Module.
FIG. 12 illustrates a start-up procedure for a gaming device. When power is applied to the gaming machine, the BIOS is initialized and the initialization code calculates a CRC16 hash value for the contents of the BIOS EPROM at step 1050. At step 1052, the BIOS EPROM is validated by comparing the calculated CRC16 hash value to the CRC16 hash stored in the BIOS. If the values do not match, an error message is displayed and all processing is stopped. Otherwise, if the hash values match, the Kontron® vendor BIOS support gains control and performs hardware identification and initialization processing at step 1054. After the Kontron® vendor BIOS support completes its initialization, control is passed to the BALLY BIOS Extension.
At step 1056, the BIOS Extension code copies the Linux Kernel Loadable image and the Initial RAM disk image from the BIOS into the gaming device's RAM memory. The BALLY BIOS Extension also copies the DSS and PVSSR Public Key bits from the BIOS into the gaming device's RAM memory at offset 0x900.
Control is then passed from the BALLY BIOS Extension to the Linux start-up code logic at step 1058. The Linux start-up code initializes the Linux kernel control blocks, memory and CPU hardware features. The Linux start-up code also calls a small command file, linuxrc, located in the Initial RAM disk. At step 1060, the linuxrc command file loads various modules such as the Bally AGK, Fault Manager, File Validation and Memory Validation Modules into the gaming device's memory from the Initial RAM disk.
The File Validation Module authenticates the Jurisdiction EPROM and the contents of all file manifests. If present, the File Validation Module will also authenticate the contents of older and/or legacy game compact flash. The Bally AGK module creates and initializes the upper level entries in the proc file system used by Bally programming support. In particular, the Bally AGK module also creates and initializes the proc file system entry/proc/agk. If activated support functions are present, Bally AGK supports read requests for reporting activated support functions.
If the modules, as shown in FIG. 11, load and initialize successfully, control is passed back to the Linux start-up code. The Linux start-up code continues the start-up process for the Linux system and loads the game and the game support. If the modules do not successfully complete initialization, a machine fault is raised and the system is halted.
After the File Validation Module is loaded from the Initial RAM disk and stored on the EGM's BIOS, the File Validation Module is initialized according to the following process. First, the PVSSR and DSS public keys that are passed by the BIOS BALLY extension loader code are stored. The BALLY BIOS extension code will save the PVSSR public key value at address x0900 In-Memory for use by the File Validation Module.
Second, the File Validation Module uses either the stored PVSSR or DSS public keys to authenticate the contents of the Jurisdiction EPROM. If the Jurisdiction contents contain the string “GG_SIGN”, the Jurisdiction contents were signed using the PVSSR public and private keys. Accordingly, the Jurisdiction contents will be authenticated with the stored PVSSR. If this string is absent, the contents of the Jurisdiction chip were signed using the DSS public and private key pair, and the stored DSS public key is used to authenticate the Jurisdiction contents.
Third, if the string “FST” appears at a predefined offset in the pre-partition area of the Game compact flash, a flag is set to identify the game compact flash as a pre-manifest type game. The flag signals that the game needs to be authenticated by using the SHA-1 hash of the entire game flash contents and the DSS signature for the hash value. Additionally, an entry is created in the proc file system, /proc/agk/game_auth, to indicate when the contents of the game compact flash was validated. Access to the game compact flash is not permitted until the contents of the game have been authenticated and the word “Done” written into the “/proc/agk/game_auth” file.
Fourth, the boot ID file is read to determine the proper partition location for the Linux kernel on the compact flash or hard disk. The boot ID file also identifies the proper partition for starting the Linux operating system environment. The Linux kernel is then initialized with the proper partition ID.
Fifth, the manifests associated with the Alpha Support compact flash and game flash are read. The PVSSR signatures of the manifest's contents are validated. Also, the memory file validation table is built. If the game flash contains manifest files signed with DSS support, a separate table containing the SHA-1 hash values of all the files within the game manifest files is created. A flag is set to indicate that the contents of the files on the game flash are validated using the SHA-1 Hash values.
Sixth, the vendor ID and release information for the Alpha Support and the Game are initialized. Next, the file validation module saves the address of where to call the file validation routine in the Linux kernel's open file code. Lastly, the file validation module is registered with the system and control is returned to the Linux start-up process.
In the event that an error is detected during initialization of the File Validation Module, a system fault is raised and an error message is presented on the display screen on the gaming device. Additionally, all further processing is halted.
FIG. 13 illustrates one embodiment of an In-Memory File Validation Table. As shown in FIG. 13, the table shows how the file validation information is stored in the gaming device's memory.
As each file is extracted from the File Validation Manifest File, its PVSSR signature is saved in the next free entry in the Signature Table. The name of the file is then hashed to create an index into the Signature Pointer Table. If an entry in the Signature Pointer table already contains a pointer to a Signature Table entry, the new Signature Table entry is chained to the one pointed to by the Signature Index Table entry. The file name of the new Signature Table entry is then stored in the file name table and the address of where it is stored is saved in the Signature Table entry. The first entry in a chain of Signature Table entries will not have a file name associated with it. File names are only saved for duplicates.
FIG. 14 illustrates one method for creating an In-Memory File Validation Table. As shown in FIG. 14, a File Validation Manifest is created for each file at step 1100. For each file in the manifest, a PVSSR signature is saved in a Signature Table Entry at step 1110. The file name is then hashed to create an index into the Signature Pointer Table at step 1112. At step 1114, a determination is made as to whether the index points to a used table entry. If the index does not point to a used table entry, the index points to the next Signature Table Entry at step 1116. The process then repeats itself for the next file at step 1110.
If the index points to a used table entry, the entry is retrieved at step 1118. At step 1120, a determination is made as to whether the next PVSSR Sig Entry is zero. If the next PVSSR value is zero, the process proceeds to step 1124. If the next PVSSR value is not zero, the process chains through the PVSSR Signature entries until a zero entry is found at step 1122. Once a zero entry is found, the address of the new Signature Table entry is saved in the next PVSSR Signature Entry at step 1124. At step 1126, the file name is copied to the File Name Table, and the address is saved in the Signature Table Entry. The pointer is updated to the next free Signature Table Entry at step 1128. The process then repeats itself for the next file at step 1110.
For a game flash that contains DSS File Validation Manifest files, a duplicate memory validation table, as shown in FIG. 15, is created that saves the SHA-1 hash values for the game file contents instead of a PVSSR signature. The processing to create the In-Memory File Validation Table using SHA-1 hash values is the same as the processing for storing a PVSSR in a memory signature table, except that the SHA-1 hash is used instead of PVSSR.
FIG. 16 illustrates one method for file validation processing in a gaming device. When a request is made to open a file that resides in a read-only partition at step 1200, the system's open code calls the file validation driver with the fully qualified name of the file to be opened.
The file validation driver performs the following operations before allowing the file open to proceed. At step 1210, the driver determines whether the file validation pointer is zero. If the file validation pointer is zero, the Linux file open process continues at step 1212, and the program continues processing at step 1214.
If the file validation pointer is not zero, the file validation driver determines whether the file has PVSSR Signature authentication at step 1216. If there is no PVSSR signature authentication, the process proceeds to step 1212. If there is a PVSSR signature authentication, a PVSSR value is calculated based on the Index value from the file name at step 1218. At step 1220, a determination is made as to whether the PVSSR Table Pointer Entry is zero. If the value is zero, a system fault is raised and processing stops at step 1222. If the PVSSR Table Pointer Entry is not zero, the Signature Table Entry is retried at step 1224.
At step 1226, a determination is made as to whether the next PVSSR Sig Entry is zero. If the next PVSSR Sig Entry is zero, then the PVSSR Signature is extracted and the file contents are authenticated at step 1228. If the file contents are deemed to be authentic at step 1230, then the Linux file opening process continues at step 1212. If the file contents are not authentic, the system faults and processing stops by calling kernel panic at step 1222. The Linux kernel panic is intercepted by the Bally fault manager code to display an error message on a display screen on the gaming device. All further processing on the gaming device is halted and no new processing can be started without manual intervention by authorized personnel to correct the problem and/or restart the gaming machine.
If at step 1226, the next PVSSR Sig Entry is not zero, then the process loops through the chain of Signature Table Entries at step 1232. If there is a file name match at step 1234, then the PVSSR Signature is extracted and the file contents are authenticated according to step 1228. If there is no file name match or the process has reached the last entry, the first Signature Table Entry is selected for authentication purposes at step 1236. If the file contents are deemed to be authentic at step 1230, then the Linux file opening process continues at step 1212. Otherwise, at the system faults and processing stops at step 1222.
Once the Linux kernel has completed all of its initializations and the Linux run environment is established, the Linux kernel passes control to the Linux command file, rc.sysinit. FIG. 17 generally illustrates the logic flow through the system to reach the rc.sysinit command file. Generally, the rc.sysinit file loads support for any hardware not contained within the Linux kernel and not started from the linuxrc command file, initializes the game processing environment, and starts the game. Some basic functions performed by the rc.sysinit command file include (but is not limited to): mounting the compact flash device on the system as read-only; setting hardware access to compact flash as R/O with no file system caching; starting background file validation support; authenticating that logically-linked files point to the correct real files; loading common and activate hardware support not included in Linux kernel; initializing video support and splash screen support after the contents of the game compact flash have been authenticated; loading any remaining hardware drivers; starting memory background memory validation support; initializing game global run-time environment variables; starting Game Manager processing; and processing background authentication.
Background authentication processes are started from the rc.sysinit processing. The background authentication process authenticates and validates the following: any partitions formatted with ext2 file system existing on the compact flash are not modified; contents of the PVSSR File Manifests and the contents of all files defined within those Manifests are authentic; contents of a DSS manifest file associated with the game flash and the file contents defined within the manifest are valid; or the SHA-1 hash value over the entire contents of the game flash (not associated with manifest file) matches the SHA-1 hash generated by the File Validation Loadable Module initialization code. If any checks fail, the system immediately halts with a message displayed on a video screen of the gaming machine. These checks insure that the media associated with the Linux Alpha Support and the Game code are not modified in any manner and that the hardware is not producing any errors or inaccurate data read results. The background process checks also insure that files from the File Validation Manifest are not modified or corrupted.
At the start of rc.sysinit processing, a program called validate-links is run. The processing associated with the validate-links program is performed before the Game Manager environment and the game is started. The validate-links program accesses File Validation Manifest files that contain all of the logical links on the Alpha support and Game compact flashes. The validate-links program extracts the logical link name and the real file name from the manifest, accesses the logical link, and then validates that the logical link points to the same real file as specified in the manifest. If the logical link does not point to the appropriate file, a system fault is raised and an error message is displayed on a gaming machine's video screen, and all processing on the EGM is halted.
In addition to running the validate-links program, a validate-files process is started at the beginning of rc.sysinit processing. Generally, on a periodic basis, the validate-files process authenticates and validates that the game code and Alpha support code on the compact flash have not been modified. The validate-files process also validates that the hardware does not give invalid information as a result of a read operation.
FIG. 18 illustrates one method for performing a background validating process. At step 1300, the validate-files is started. The boot partition ID is obtained from the boot.id file at step 1302, and the public keys are obtained from the proc file system at step 1304. At step 1306, a list of Alpha Support File Validation Files is obtained.
At step 1308, the validate-files program first reads control blocks maintained by the EXT2 file system. The EXT2 file system is used to format the partitions on the Alpha Support and gaming device's storage media. The partitions are divided into physical blocks of storage having the same size. The EXT2 file system maintains a table that indicates whether a physical block is used and unused. When data is written to one of the file system's unused blocks, the file system's table is modified to indicate that the block is no longer free. Additionally, the file system updates a block that keeps track of all the used blocks within the partition.
At step 1308, after the validate-files program reads the control blocks, the program verifies that the control information relating to the free and unused blocks has not changed since the last time the control blocks were read. If a change is detected, the machine is halted and a message displayed on the EGM's video screen at step 1310.
Next, the program determines whether a “FST” string appears in the pre-partition area of the Game compact flash at step 1312. If present, a flag is set to identify the game compact flash as a pre-manifest type game at step 1314. The flag signals that the game needs to be authenticated by using the SHA-1 hash of the entire game flash contents and the DSS signature for the hash value. At step 1316, the validate-files program determines whether the Game compact flash includes a DSS manifest. If present, a DSS Game Flag is set at step 1318.
After the partition control data is authenticated, all of the PVSSR manifests are processed at step 1322. The PVSSR manifest processing includes reading and authenticating the manifest contents for each Alpha support manifest at step 1330. If the manifest contents are determined to be authentic at step 1332, the contents of each file in the manifest is read and authenticated at step 1334. If the contents of the manifest or the file's contents are not authenticated at steps 1332 and 1336, an error message is displayed on the gaming device's video screen at step 1310 and processing is stopped.
If DSS Manifest flag is determined to be present at step 1324, a request is issued to File Validation Module to activate a Linux Kernel thread (Game Validation) that authenticates the DSS signature of the SHA-1 hash of Game compact flash's contents. At step 1326, a SHA-1 hash value of the Game Flash contents is calculated and saved into memory. The calculated SHA-1 hash value is then compared to the hash value stored in the system RAM at step 1328. For DSS manifest processing, the manifest contents for each Alpha support manifest is read and authenticated at step 1330. If the manifest contents are determined to be authentic at step 1340, the contents of each file in the manifest is read and authenticated at step 1342. If the SHA-1 values do not match or the contents of the manifest or the file's contents are not authenticated at steps 1340 and 1342, an error message is displayed on the gaming device's video screen at step 1310 and processing is stopped.
Once the Game flash contents are authenticated, the /proc/agk/game_auth file is updated to indicate Game flash authentication is done. This allows the rc.sysinit command file to initialize the Game Manager environment and access the game flash. It also signals the validate-files process so it can continue to periodically re-calculate the SHA-1 hash value of the compact flash's contents. The file is validated if the calculated hash matches the original hash value.
In one embodiment, the gaming device may be configured to support host downloaded information. However, any modification made to the gaming device's storage media requires that an existing File Validation Manifest File be replaced with a new File Validation Manifest File to reflect the changes to the files stored on the gaming device's storage media. Since the File Validation Manifest is being changed, the gaming device must be stopped and restarted. This is required to allow the secure BIOS to authenticate and validate the new operating environment and File Validation Manifests, and to allow the validation driver to rebuild the In-Memory File Validation Table.
Accordingly, one modification procedure is carried out according to the following method. First, the gaming machine is disabled, and no player activity is allowed on the gaming machine. File validation is suspended. Files to be deleted from the storage media are first rewritten with all zeroes prior to deletion. All updates are made to the existing files, and any new files are added. The File Validation Manifest file is then replaced. All unused blocks on the storage media's partition are filled with zeros. The File Validation Tables are re-created with the new manifest. This insures that any previously validated files will be validated again. The logical-links are also validated. Once completed, the gaming machine is re-enabled to a run state.
In another embodiment, the gaming device includes a System Fault Manager and hardware Watchdog support. Generally, the hardware watchdog register is used by the Fault Management Support to insure that all required processes and threads in the gaming software are active and functioning. In one embodiment, the Faultdog support interfaces with the Watchdog support in order to detect whether a required thread no longer exists and to restart the EGM after a fault has been detected, reported and acknowledged. The Faultdog Manager is the only process in the system that interacts with the Watchdog support, thereby insuring its integrity.
In one embodiment, the hardware Watchdog support includes a Watchdog circuit having a timeout counter and an input/output (I/O) Halt from the Protection Circuit. If the watchdog circuit is enabled, the timeout counter needs to be regularly cleared before a timeout period. If a timeout occurs, the Watchdog circuit indicates that the CPU must be locked-up and the CPU's hardware reset.
The following tables illustrate one embodiment of the watchdog support.


BIT	Signal	Function

D0	TO_0	Watchdog Timeout value bit 0
D1	TO_1	Watchdog Timeout value bit 1
D2	TO_2	Watchdog Timeout value bit 2
D3	TO_3	Watchdog Timeout value bit 3
D4	TO_4	Watchdog Timeout value bit 4
D5	TO_5	Watchdog Timeout value bit 5
D6	TO_6	Watchdog Timeout value bit 6
D7	/WCHDOG_EN	Watchdog & I/O Halt Enable
		(Protection circuit), active low


	FUNCTION

			Clear
	Manual	Watchdog	Watchdog	State
	CPU	& I/O Halt	Timer	after
BIT	Reset	Disable	(Enabled)	Reset

D0
0	Any	Timeout	1
D1	0	Non-Zero	Value		1
D2	0	Value		1
D3	0			1
D4	0			1
D5	0			1
D6	0			1
D7	0	1	0	1

The Watchdog enable bit enables both the Watchdog and the I/O Halt from the Protection Circuit. Bits TO[6:0] set the timeout period ranging from 0.1 to 12.8 seconds with a resolution of 0.1 seconds. Because the timer and the timeout register are not synchronized the timeout period is provided with 0.1 seconds of tolerance. As shown above, Bit 7 high disables the Watchdog's CPU reset and the Protection Circuit's I/O halt signals.
When enabling the Watchdog, care must be taken because the Watchdog counter is free-running. As a result, it is possible that the timeout value may match the counter when the Watchdog is enabled, thereby resulting in a CPU reset that initiates an endless cycle of resets. To prevent this problem, the Watchdog is enabled on power-up with the timeout initially set to the maximum of 12.8 seconds. Additionally, once the Protection Circuit times out, the Protection Circuit may only be reset with a hardware reset. If the Protection Circuit is being used, servicing starts before its first 15 minute timeout. These two limitations prevent enabling and disabling the Watchdog with different applications. As a result, the Watchdog should only be initialized at power-up.
The Watchdog counter is automatically reset when a timeout value is written and bit-7 (/WCHDOG_EN) is low. The manual CPU reset is established by writing all zeros to the ‘HW Watchdog Register’. In order to prevent glitches or inadvertent resets of the system when enabling the Watchdog, the timeout value should be a non-zero value prior to clearing bit 7.
The Software Faultdog support includes the following functions: monitor all registered processes to detect errors or unauthorized removal of registered processes; manage the hardware Watchdog Register to avoid system hangs; display generic user message and turn on top box lights when a fatal error occurs; log detailed fault description message when fatal error occurs; display detail fault description message when attendant key is turned; display a message when the door is opened after a fault has occurred; display a message when a Game or OS flash has been removed; automatically detect cabinet-type and port configuration; automatically reboot the gaming device when the attendant key is turned for the second time after a fatal error; provide independence from any specific video or I/O requirements; and catch kernel panic errors, show detailed information about kernel panic, and prevent the gaming device from automatically rebooting after the panic occurs.
All files, partition, and memory validation threads register with the Faultdog Manager when they are first started. The Faultdog Monitoring Support continuously runs in the background checking to see if registered threads are still active in the system. If a registered thread is no longer active on the system, a fatal fault is raised. This fault is written to the fault log, and the appropriate message is displayed on the video screen of the gaming device. Typically, attendant intervention is required to clear this fault and restart the gaming device via a power-up cycle.
The Faultdog Manager also resets the hardware Watchdog Timer to signal that the system is still alive. If the Faultdog Manager does not reset the hardware Watchdog Timer, the timer will expire; thereby causing a system failure. The Faultdog Driver and process insure that all of the required processes are still active and that the hardware Watchdog Timer is used to verify that the Faultdog Code is still active.
Any errors detected by the Faultdog Management Code will generate an error message for display on the video screen of the gaming device. Optionally, the candle lights, on the gaming device, may be turned on in response to errors detected by the Faultdog Management Code. Optionally, the errors are written to a Faultdog Error Log.
Generally, Faultdog Error logging support is only available after the BIOS code has finished processing, and the Faultdog Support installed. The Faultdog Support is installed as the first support during Linux kernel initialization and setup process and prior to any other authentication and validation code in system.
The error message and the error log includes the following information: date and time stamp for the error occurrence; task ID of the task that was running at the time of the error; description of the type of error that was encountered; and the name of the file being processed if the error was caused by a file validation.
When the G2S Download support is introduced into the system, any authorized regulatory monitoring authority will be able to request a copy of the error logs to be transmitted to them along with any relevant validation data.
It should be noted that, while some embodiments have been described in the context of a gaming machine, the components of any device can be verified using the embodiments described herein. By way of example, and not by way of limitation, other exemplary devices that can be verified include: a kiosk, a cashier device, a plasma signage controller, a DNS server, a DHCP server, a database server, a web server, a cryptographic device, a firewall, a load balancer, a network monitoring unit, a network router, a download server, a certificate authority server, a cashless server, a progressive controller, a tournament controller, a display controller, a networking device, an Ethernet switch, a network hub, a cash transaction server, a third party payment server, a prize redemption machine, in room gaming device, a bingo game controller, a lottery game controller, a class II gaming device, a class III gaming device, a lottery gaming device, an amusement gaming device, an arcade gaming machine, a regulator monitoring device, a VPN device; a player tracking device; a player marketing device, a slot management system, a home game console, an ATM banking machine, a debit card reader, a point of sale system, a cash register, a retail scanner, a RFID reader, a location security monitoring/security input device, a military device, a vending machine, a stock transaction server, a banking server, a cell phone, a personal digital assistant, a laptop computing device, an electronic wallet device, a smart card, a set-top box, a monetary input/output device, a biometric device, a user authentication device, a personal media player, a software network updatable device, a handheld scanner, a currency handler/counter, a lottery ticket purchase/redemption device, a player bingo device, a monitor, a television, a fax device, an electronic money transfer device, a USB device, a Bluetooth device, a fire wire capable device, a wi-fi enabled device, a robotic device, or a handheld gaming device or any other device that requires files to be verified in a timely manner.
The various embodiments described above are provided by way of illustration only and should not be construed to limit the invention. Those skilled in the art will readily recognize various modifications and changes that may be made to the claimed invention without following the example embodiments and applications illustrated and described herein, and without departing from the true spirit and scope of the claimed invention, which is set forth in the following claims.

Claims

1. A method for verifying a gaming component, the method comprising:

creating a manifest file for a gaming component, wherein the manifest file includes contents of each file from the gaming component;

generating a digital signature for each file from the gaming component, wherein the digital signature is created by using the contents of each file;

saving each digital signature with each file in the manifest file;

performing a digital signature calculation on a file accessed during a bootup process;

validating the contents of the accessed file by comparing the calculated digital signature to the saved digital signature; and

presenting an error message on a video display when the contents of the accessed file is not validated.

2. The method of claim 1, further comprising:

generating a digital signature of the completed manifest file; and

saving the digital signature of the completed manifest file in a header of the manifest file.

3. The method of claim 2, further comprising:

performing a digital signature calculation on the completed manifest file;

validation the manifest file by comparing the calculated digital signature for the completed manifest file to the saved digital signature.

4. The method of claim 1, wherein the digital signature is a Pintsov-Vanstone Signature Scheme with Partial Message Recovery (PVSSR) signature.

5. A method of verifying a gaming component, the method comprising:

determining if the manifest is authentic, the manifest including component information and a stored digital signature for the gaming component;

performing a digital signature calculation using the contents of the component to produce a calculated digital signature if the manifest is authentic;

verifying the gaming component by comparing the calculated digital signature to the stored digital signature; and

loading the gaming component if the calculated digital signature and the stored digital signature are equal.

6. The method of claim 5, wherein authenticating the manifest includes performing a digital signature algorithm on the manifest.

7. The method of claim 5, wherein the component is verified when the component is retrieved for operation of a device.

8. The method of claim 5, wherein the component is verified on a continuing basis during operation of a device.

9. The method of claim 5, wherein the digital signature is a Pintsov-Vanstone Signature Scheme with Partial Message Recovery (PVSSR) signature.

10. A method for verifying a gaming component, the method comprising:

identifying a validation protocol used to create a digital signature for a gaming component;

performing a digital signature calculation using the contents of the component to produce a calculated digital signature;

11. The method of claim 10, wherein authenticating the manifest includes performing a digital signature algorithm on the manifest.

12. The method of claim 10, wherein the component is verified when the component is retrieved for operation of a device.

13. The method of claim 10, wherein the component is verified on a continuing basis during operation of a device.

14. The method of claim 10, wherein the digital signature is a Pintsov-Vanstone Signature Scheme with Partial Message Recovery (PVSSR) signature or a SHA-1 Hash.