Classifications

• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06F—ELECTRIC DIGITAL DATA PROCESSING
  • G06F21/00—Security arrangements for protecting computers, components thereof, programs or data against unauthorised activity
  • G06F21/70—Protecting specific internal or peripheral components, in which the protection of a component leads to protection of the entire computer
  • G06F21/78—Protecting specific internal or peripheral components, in which the protection of a component leads to protection of the entire computer to assure secure storage of data
  • G06F21/79—Protecting specific internal or peripheral components, in which the protection of a component leads to protection of the entire computer to assure secure storage of data in semiconductor storage media, e.g. directly-addressable memories
• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06F—ELECTRIC DIGITAL DATA PROCESSING
  • G06F15/00—Digital computers in general; Data processing equipment in general
• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06F—ELECTRIC DIGITAL DATA PROCESSING
  • G06F21/00—Security arrangements for protecting computers, components thereof, programs or data against unauthorised activity
• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06F—ELECTRIC DIGITAL DATA PROCESSING
  • G06F21/00—Security arrangements for protecting computers, components thereof, programs or data against unauthorised activity
  • G06F21/30—Authentication, i.e. establishing the identity or authorisation of security principals
  • G06F21/31—User authentication
• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06F—ELECTRIC DIGITAL DATA PROCESSING
  • G06F21/00—Security arrangements for protecting computers, components thereof, programs or data against unauthorised activity
  • G06F21/60—Protecting data
  • G06F21/62—Protecting access to data via a platform, e.g. using keys or access control rules
  • G06F21/6218—Protecting access to data via a platform, e.g. using keys or access control rules to a system of files or objects, e.g. local or distributed file system or database
• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06F—ELECTRIC DIGITAL DATA PROCESSING
  • G06F2221/00—Indexing scheme relating to security arrangements for protecting computers, components thereof, programs or data against unauthorised activity
  • G06F2221/21—Indexing scheme relating to G06F21/00 and subgroups addressing additional information or applications relating to security arrangements for protecting computers, components thereof, programs or data against unauthorised activity
  • G06F2221/2103—Challenge-response

Definitions

• This invention relates in general to memory systems, and in particular to a memory system with versatile content control features.
• the computing device market is developing in the direction of including content storage on mobile storage devices so as to increase the average revenue by generating more data exchanges. This means that the content in a mobile storage medium has to be protected when used on a computing device.
• Content includes valuable data, which may be data owned by a party other than the one that manufactures or sells the storage device.
• the protection of content in a mobile storage medium can involve the encryption of data in the medium so that only authorized users or applications have access to keys used for encrypting data stored in the medium.
• the key used for encrypting and decrypting data is stored in devices external to the mobile storage medium. In such circumstances, the company or individual who owns proprietary interest in the content may not have much control over the usage of the content in the medium. Since the key used for encrypting data in the medium exists external to the medium, this key may be passed from one device to another in a manner not subject to control by the content proprietor. The owner of proprietor interest will be in the better position to control access to the content in the medium if the encryption-decryption key is stored in the medium itself and substantially inaccessible to external devices, according to one of the features of the invention.
• this feature provides portability to secured content.
• the storage device containing secured content ciphered with such a key can be used for access by a variety of host devices without the danger of security breach, since the device has exclusive control of access to the key. Only those host devices with the proper credentials are able to access the key.
• Another feature of the invention is based on the recognition that an access policy may be stored which grants different permissions (e.g. to different authorized entities) for accessing data stored in the medium.
• a system incorporating a combination of the two above features is particularly advantageous.
• the content owner or proprietor has the ability to control access to the content by using keys that are substantially inaccessible to external devices and at the same time has the ability to grant different permissions for accessing content in the medium. Thus, even where external devices gain access, their access may still be subject to the different permissions set by the content owner or proprietor recorded in the storage medium.
• Yet another feature is based on the recognition that when the above-described policy, where different permissions are granted to different authorized entities, is implemented in a flash memory, this results in a particularly useful medium for content protection.
• the host device provides a key reference or ED, while the memory system generates a key value in response which is associated with the key ED, where the key value is used in cryptographic processing data in a file associated with the key ED.
• the host associates the key ED with the file to be processed cryptographically by the memory system.
• the key ED is used by the computing device and memory as the handle through which the memory retains complete and exclusive control over the generation and use of the key value for cryptographic processes, while the host retains control of files.
• the card controller manages the file system.
• the device controller In many other types of mobile storage devices, such as flash memories, magnetic or optical discs, the device controller is not aware of the file system; instead, the device controller relies on a host device (e.g. a personal computer, digital camera, MP3 player, personal digital assistants, cellular phones) to manage the file system.
• a host device e.g. a personal computer, digital camera, MP3 player, personal digital assistants, cellular phones
• the various aspects of this invention may be readily incorporated into such types of storage devices where the device controller is not aware of the file system. This means that the various features of this invention may be practiced on a wide variety of existing mobile storage devices without requiring a re-design of such devices to make the device controller in such devices become aware of and able to manage the file system.
• a tree structure stored in the storage medium provides control over what an entity can do even after gaining access.
• Each of the nodes of the tree specifies permissions by an entity who has gained entry through such node of the tree.
• Some trees have different levels, where the permission or permissions at a node of the tree has a predetermined relationship to permission or permissions at another node at a higher or lower or the same level in the same tree.
• Another feature of the invention is based on the recognition that two or more trees which are preferably hierarchical may be provided for controlling access to the memory.
• Each tree comprises nodes at different levels for controlling access to data by a corresponding set of entities where a node of each tree specifies permission or permissions of the corresponding entity or entities for accessing memory data.
• the permission or permissions at a node of each of the trees has a predetermined relationship to permission or permissions at another node at a higher or lower level in the same tree.
• the mobile storage device may be provided with a system agent that is able to create at least one hierarchical tree comprising nodes at different levels for controlling access to data stored in the memory by corresponding entities.
• Each node of the tree specifies permission or permissions of a corresponding entity or entities for accessing memory data.
• the permission or permissions at the node of each of the trees has a predetermined relationship to permission or permissions at nodes at a higher or lower or the same level in the same tree.
• the mobile storage devices may be issued without any trees already created so that the purchaser of the devices has a free hand in creating hierarchical trees adapted to the applications the purchaser has in mind.
• the mobile storage devices may also be issued with the trees already created so that a purchaser does not have to go through the trouble of creating the trees.
• certain functionalities of the trees can become fixed after the devices are made so that they cannot be further changed or altered. This provides greater control over access to the content in the device by the content owner.
• the system agent can preferably be disabled so that no additional trees can be created.
• Another aspect of the invention is based on the recognition that a mechanism or structure may be provided to divide a memory into partitions and so that at least some data in the partitions can be encrypted with a key, so that in addition to authentication that is required for accessing some of the partitions, access to one or more keys may be required to decrypt the encrypted data in such partitions.
• FIG. 1 is a block diagram of a memory system in communication with the host device useful for illustrating this invention.
• FIG. 2 is a schematic view of different partitions of a memory and of unencrypted and encrypted files stored in different partitions where access to certain partitions and the encrypted files is controlled by access policies and authentication procedures to illustrate an embodiment of the invention.
• FIG. 3 is a schematic view of a memory illustrating the different partitions in the memory.
• Fig. 4 is a schematic view of file location tables for the different partitions of the memory shown in Fig. 3 where some of the files in the partitions are encrypted to illustrate an embodiment of the invention.
• Fig. 5 is a schematic view of access control records in an access controlled record group and the associated key references to illustrate an embodiment of the invention.
• Fig. 6 is a schematic view of tree structures formed by access controlled records groups and access controlled records to illustrate an embodiment of the invention.
• Fig. 7 is a schematic diagram of a tree illustrating three hierarchical trees of access controlled record groups to illustrate a process of formation of the trees.
• Fig. 8A and 8B are flow charts illustrating the processes carried out by a host device and a memory device such as a memory card for creating and using a system access control record.
• Fig. 9 is a flow chart illustrating a process using a system access control record to create an access controlled record group to illustrate the invention.
• Fig. 10 is a flow chart illustrating a process for creating an access control record.
• FIG. 11 is a schematic view of two access control record groups useful for illustrating a particular application of the hierarchical tree.
• Fig. 12 is a flow chart illustrating a process for delegation of specific rights.
• Fig. 13 is a schematic view of an access controlled record group and an access control record to illustrate the process of delegation of Fig. 12.
• Fig. 14 is a flowchart illustrating the process for creating a key for the purpose of encryption and/or decryption.
• Fig. 15 is a flow chart illustrating a process for removing access rights and/or permission for data access according to an accessed controlled record.
• Fig. 16 is a flow chart illustrating a process for requesting access when access rights and/or permission to access has been deleted or has expired.
• Fig. 17A and Fig. 17B are schematic views illustrating an organization of a rule structure for authentication and policies for granting access to cryptographic keys to illustrate another embodiment of the invention.
• Fig. 18 is a flow diagram illustrating sessions of authentication and access when some sessions are open.
• Fig. 19-22 are flow charts illustrating different authentication processes.
• the memory system 10 includes a central processing unit (CPU) 12, a buffer management unit (BMU) 14, a host interface module (HIM) 16 and a flash interface module (FEVl) 18, a flash memory 20 and a peripheral access module (PAM) 22.
• Memory system 10 communicates with a host device 24 through a host interface bus 26 and port 26a.
• the flash memory 20 which may be of the NAND type, provides data storage for the host device 24.
• the software code for CPU 12 may also be stored in flash memory 20.
• FIM 18 connects to the flash memory 20 through a flash interface bus 28 and port 28a.
• HIM 16 is suitable for connection to a host system like a digital camera, personal computer, personal digital assistants (PDA), digital media players, MP-3 players, cellular telephones or other digital devices.
• the peripheral access module 22 selects the appropriate controller module such as FIM, HIM and BMU for communication with the CPU 12.
• controller module such as FIM, HIM and BMU for communication with the CPU 12.
• all of the components of system 10 within the dotted line box may be enclosed in a single unit such as in memory card or stick 10' and preferably encapsulated.
• the buffer management unit 14 includes a host direct memory access (HDMA) 32, a flash direct memory access (FDMA) 34, an arbiter 36, a buffer random access memory (BRAM) 38 and a crypto-engine 40.
• the arbiter 36 is a shared bus arbiter so that only one master or initiator (which can be HDMA 32, FDMA 34 or CPU 12) can be active at any time and the slave or target is BRAM 38.
• the arbiter is responsible for channeling the appropriate initiator request to the BRAM 38.
• the HDMA 32 and FDMA 34 are responsible for data transported between the HIM 16, FIM 18 and BRAM 38 or the CPU random access memory (CPU RAM) 12a.
• the operation of the HDMA 32 and of the FDMA 34 are conventional and need not be described in detail herein.
• the BRAM 38 is used to store data passed between the host device 24 and flash memory 20.
• the HDMA 32 and FDMA 34 are responsible for transferring the data between HIM 16/FIM 18 and BRAM 38 or the CPU RAM 12a and for indicating sector completion.
• memory system 10 For improved security of the content stored in memory 20, memory system 10 generates the key value(s) that are used for encryption and/or decryption, where this value(s) is substantially not accessible to external devices such as host device 24.
• encryption and decryption is typically done file by file, since the host device reads and writes data to memory system 10 in the form of files.
• memory device 10 is not aware of files or file systems. While memory 20 does store a file allocation table (FAT) where the logical addresses of the files are identified, the FAT is typically accessed and managed by the host device 24 and not by the controller 12.
• FAT file allocation table
• the controller 12 will have to rely on the host device to send the logical addresses of the data in the file in memory 20, so that the data of the particular file can be found and encrypted and/or decrypted by system 10 using the key value(s) available only to system 10.
• the host device provides a reference for each of the key values generated by system 10, where such reference may simply be a key ID.
• the Host 24 associates each file that is cryptographically processed by system 10 with a key ID
• the system 10 associates each key value that is used to cryptographically process data with a key ID provided by the host.
• the host requests that a file be cryptographically processed, it will send the request along with a key ID along with the logical addresses of data to be fetched from or stored in memory 20 to system 10.
• System 10 generates a key value and associates the key ID provided by the host 24 with such value, and performs the cryptographic processing. In this manner, no change needs to be made in the manner memory system 10 operates while allowing it to completely control the cryptographic processing using the key(s), including exclusive access to the key value(s). hi other words, system 10 continues to allow the host 24 to manage the files by having exclusive control of FAT, while it maintains exclusive control for the generation and management of the key value(s) used for cryptographic processing.
• the host device 24 has no part in the generation and management of the key value(s) used for cryptographic processing of data.
• the key BD provided by the host 24 and the key value generated by the memory system form two attributes of a quantity referred to below as the "content encryption key" or CEK in one of the embodiments. While the host 24 may associate each key ID with one or more files, host 24 may also associate each key ID with unorganized data or data organized in any manner, and not limited to data organized into complete files.
• system 10 hi order for a user or application to gain access to protected content or area in system 10, it will need to be authenticated using a credential which is pre-registered with system 10.
• a credential is tied to the access rights granted to the particular user or application with such credential, hi the pre-registration process, system 10 stores a record of the identity and credential of the user or application, and the access rights associated with such identity and credential determined by the user or application and provided through the host 24.
• the pre-registration has been completed, when the user or application requests to write data to memory 20, it will need to provide through the host device its identity and credential, a key ID for encrypting the data, and the logical addresses where the encrypted data is to be stored.
• System 10 generates a key value and associates this value with the key ID provided by the host device, and stores in its record or table for this user or application the key ID for the key value used to encrypt the data to be written. It then encrypts the data and stores the encrypted data at the addresses designated by the host as well as the key value it generated.
• System 10 When a user or application requests to read encrypted data from memory 20, it will need to provide its identity and credential, the key ED for the key previously used to encrypt the requested data, and the logical addresses where the encrypted data is stored. System 10 will then match the user or application identity and credential provided by the host to those stored in its record. If they match, system 10 will then fetch from its memory the key value associated with the key ID provided by the user or application, decrypt the data stored at the addresses designated by the host device using the key value and send the decrypted data to the user or application.
• system 10 Since system 10 maintains a record of the users or application identities and credentials, the key IDs they have access to, and the associated access rights to each of the key IDs, it is possible for system 10 to add or delete key IDs and alter access rights associated with such key IDs for particular users or applications, to delegate access rights from one user or application to another, or even to delete or add records or tables for users or applications, all as controlled by a properly authenticated host device.
• the record stored may specify that a secure channel is required for accessing certain keys. Authentication may be done using symmetric or asymmetric algorithms as well as passwords.
• the portability of the secured content in the memory system 10 Since the key value is generated by the memory system and substantially not available to external systems, when the memory system or a storage device incorporating the system is transferred from one external system to another, security of the content stored therein is maintained, and external systems are not able to access such content unless they have been authenticated in a manner completely controlled by the memory system. Even after being so authenticated, access is totally controlled by the memory system, and external systems can access only in a manner controlled according to preset records in the memory system. If a request does not comply with such records, the request will be denied.
• the flash memory 20 may have its storage capacity divided into a number of partitions: a user area or partition and custom partitions.
• the user area or partition PO is accessible to all users and applications without authentication. While all bit values of data stored in the user area can be read or written to by any application or user, if the data read is encrypted, the user or application without authority to decrypt would not be able to access the information represented by the bit values stored in a user area.
• files 102 and 104 stored in user area PO. Also stored in the user area are unencrypted files such as 106 which can be read and understood by all applications and users. Thus, symbolically, the files that are encrypted are shown with locks associated with them such as for files 102 and 104.
• memory 20 also includes protected custom partitions such as partitions Pl and P2 which cannot be accessed without prior authentication. The authentication process permitted in the embodiments in this application is explained below.
• a variety of users or applications may access the files in memory 20.
• users 1 and 2, and applications 1-4 (running on devices) are shown in Fig. 2.
• they are first authenticated by an authentication process in a manner explained below.
• the entity that is requesting access needs to be identified at the host side for role based access control.
• the entity requesting access first identifies itself by supplying information such as "I am application 2 and I wish to read file 1.”
• Controller 12 matches the identity, authentication information and request against the record stored in memory 20 or controller 12. If all requirements are met, access is then granted to such entity.
• user 1 is allowed to read from and write to file 101 in partition Pl, but can only read files 102 and 104 in addition to user 1 having unrestricted rights to read from and write to files 106 in PO.
• User 2 is not allowed access to file 101 and 104 but has read and write access to file 102.
• users 1 and 2 have the same login algorithm (AES) while applications 1 and 3 have different login algorithms (e.g. RSA and 001001) which are also different from those of users 1 and 2.
• the Secure Storage Application is a security application of the memory system 10, and illustrates an embodiment of the invention, which can be used to implement many of the above-identified features.
• SSA may be embodied as software or computer code with database stored in the memory 20 or a non-volatile memory (not shown) in CPU 12, and is read into RAM 12a and executed by CPU 12.
• the acronyms used in reference to the SSA are set forth in the table below:
• the data are files that would otherwise be stored plainly on a mass-storage device of some kind.
• the SSA system sits atop of the storage system and adds the security layer for the stored host files.
• the main task of the SSA is to manage the different rights associated with the stored (and secured) content in the memory.
• the memory application needs to manage multiple users and content rights to multiple stored content. Host applications from their side, see drives and partitions that are visible to such applications, and file allocation tables (FATs) that manage and portray the locations of the stored files on the storage device.
• FATs file allocation tables
• the storage device uses NAND flash chip divided to partitions, although other mobile storage devices may also be used and are within the scope of this invention.
• partitions are continuous threads of logical addresses, where a start and an end address define their boundaries. Restrictions may therefore be imposed on access to hidden partitions, if desired, by means of software (such as software stored in memory 20) that associates such restrictions with the addresses within such boundaries.
• Partitions are fully recognizable to the SSA by their logical address boundaries that are managed by it.
• the SSA system uses partitions to physically secure data from unauthorized host applications. To the host, the partitions are a mechanism of defining proprietary spaces in which to store data files. These partitions can either be public, where anyone with access to the storage device can see and be aware of the partition's presence on the device, or private or hidden, where only the selected host applications have access to and are aware of their presence in the storage device.
• FIG. 3 is a schematic view of a memory illustrating the partitions of the memory: PO, Pl, P2 and P3 (obviously fewer or more partitions than four may be employed), where PO is a public partition which can be accessed by any entity without authentication.
• a private partition (such as Pl, P2 or P3) hides the access to the files within it.
• the flash device e.g. flash card
• the flash device delivers protection of the data files inside the partition.
• This kind of protection engulfs all of the files residing in the hidden partition by imposing restrictions on access to data stored at the logical addresses within the partition, hi other words, the restrictions are associated with a range of logical addresses. All of the users/hosts that have access to that partition will have unlimited access to all of the files inside.
• the SSA system provides another level of security and integrity per file - or groups of files - using keys and key references or Key IDs.
• a key reference or key ID of a particular key value used for encrypting data at different memory addresses can be analogized to a container or domain that contains the encrypted data. For this reason, in Fig. 4, the key references or key IDs (e.g. "key 1" and "key 2”) are shown graphically as areas surrounding the files encrypted using the key values associated with the key IDs.
• File A is accessible to all entities without any authentication, since it is shown as not enclosed by any key ID.
• File B in the public partition can be read or overwritten by all entities, it contains data encrypted with a key with ID "key 1", so that the information contained in File B is not accessible to an entity unless such entity has access to such key.
• any host that can access a partition public or private
• unauthorized users can only corrupt it. They preferably cannot alter the data without detection or use it.
• this feature can allow only the authorized entities to use the data.
• Files B and C are also encrypted using a key with key ED "key 2" in PO.
• CEK Content Encryption Keys
• the CEKs are generated by the flash device (e.g. flash card), used internally only, and kept as secrets from the outside world.
• the data that is encrypted or ciphered may also be either hashed or the cipher is chain blocked to ensure data integrity.
• ACRs are organized in groups called ACR Groups or AGPs. Once an ACR has successfully authenticated, the SSA system opens a Session through which any of the ACR' s actions can be executed..
• the SSA system manages one or more public partitions, also referred to as the user partition(s).
• This partition exists on the storage device and is a partition or partitions that can be accessed through the standard read write commands of the storage device. Getting information regarding the size of the partition(s) as well as its existence on the device preferably cannot be hidden from the host system.
• the SSA system enables accessing this partition(s) either through the standard read write commands or the SSA commands. Therefore, accessing the partition preferably cannot be restricted to specific ACRs.
• the SSA system can enable the host devices to restrict the access to the user partition. Read and write accesses can be enabled/disabled individually. All four combinations (e.g. write only, read only (write protect), read and write and no access) are allowed.
• the SSA system enables ACRs to associate key IDs with files within the user partition and encrypt individual files using keys associated with such key IDs. Accessing encrypted files within the user partitions as well as setting the access rights to the partitions will be done using the SSA command set (refer to Appendix A for detailed description of the SSA commands — In the Appendix, key ID is referred to as "domain" ). The above features also apply to data not organized into files. SSA partitions
• the SSA system will preferably not allow the host device to access an SSA partition, other than through a session (described below) established by logging onto an ACR. Similarly, preferably the SSA will not provide information regarding the existence, size and access permission of an SSA partition, unless this request is coming through an established session.
• Access rights to partitions are derived from the ACR permissions. Once an ACR is logged into the SSA system, it can share the partition with other ACRs (described below). When a partition is created, the host provides a reference name or ED (e.g. P0-P3 in Figs. 3 and 4) for the partition. This reference is used in further read and write commands to the partition.
• ED reference name
• All available storage capacity of the device is preferably allocated to the user partition and the currently configured SSA partitions. Therefore, any repartition operation may involve reconfiguration of the existing partitions. The net change to the device capacity (sum of sizes of all partitions) will be zero.
• the IDs of the partitions in the device memory space are defined by the host system.
• the host system can either repartition one of the existing partitions into two smaller ones or, merge two existing partitions (which may or may not be adjacent) into one.
• the data in the divided or merged partitions can be either erased or left untouched, at the host's discretion.
• a file When a file is written to a certain hidden partition, it is hidden from the general public. But, once an entity (hostile or not) gets knowledge and access to this partition the file becomes available and plain to see. To further secure the file, the SSA can encrypt it in the hidden partition, where the credentials for accessing the key for decrypting the file are preferably different from those for accessing the partition. Due to the fact that files are not something that the SSA is aware of (totally controlled and managed by the host), associating a CEK with a file is a problem. Linking the file to something the SSA acknowledges - the key ID, rectifies this. Thus, when a key is created by the SSA, the host associates the key ID for this key with the data encrypted using the key created by the SSA.
• the key value and key ID provide logical security. All data associated with a given key ID, regardless of its location, is ciphered with the same content encryption key (CEK) whose reference name or key ID is uniquely provided at creation by the host application. If an entity obtains access to a hidden partition (by authenticating through an ACR) and wishes to either read or write an encrypted file within this partition, it needs to have access to the key ID that is associated with the file. When granting access to the key for this key ID, the SSA loads the key value in CEK associated with this key ID and either decrypts the data before sending it to the host or encrypts the data before writing it to the flash memory 20.
• CEK content encryption key
• a key value in CEK associated with a key ID is randomly created once by the SSA system and maintained by it. No one outside the SSA system has knowledge or access to this key value in CEK. The outside world only provides and uses a reference or key ID, not the key value in CEK. The key value is entirely managed and only accessible by the SSA [0072]
• the SSA system protects the data associated with the key ID using any one (user defined) of the following cipher modes (the actual cryptographic algorithms used, as well as the key values in CEKs, are system controlled and not revealed to the outside world):
• Block mode - Data is divided into blocks, each one of them, encrypted individually. This mode is generally considered less secure and susceptive to dictionary attacks, However, it will allow users to randomly access any one of the data blocks.
• Chained mode - Data is divided into blocks, which are chained during the encryption process. Every block is used as one of the inputs to the encryption process of the next one. This mode, although considered as more secure, requires that the data is always written and read sequentially from start to end, creating an overhead not always acceptable to the users.
• the SSA is designed to handle multiple applications where each one of them is represented as a tree of nodes in the system database. Mutual exclusion between the applications is achieved by ensuring no cross talk between the tree branches.
• the ACR is an individual login point to the SSA system.
• the ACR holds the login credentials and the authentication method. Also residing in the record are the login permissions within the SSA system, among which are the read and write privileges. This is illustrated in Fig. 5, which illustrates n ACRs in the same AGP. This means that at least some of the n ACRs may share access to the same key. Thus, ACR #1 and ACR #n share access to a key with key ID "key 3", where ACR#1 and
• ACR#n are the ACR IDs, and "key 3" is a key ID for the key that is used to encrypt data associated with "key 3". The same key can also be used to encrypt and/or decrypt multiple files, or multiple sets of data.
• the SSA system supports several types of login onto the system where authentication algorithms and user credentials may vary, as may the user's privileges in the system once he logged in successfully.
• Fig. 5 again illustrates different login algorithms and credentials.
• ACR#1 requires a password login algorithm and password as credential
• ACR#2 requires a PKI (public key infrastructure) login algorithm and public key as credential.
• PKI public key infrastructure
• ACRs may share common interests and privileges in the system such as in keys with which to read and write. To accomplish that, ACRs with something in common are grouped in AGPs - ACR Groups. Thus, ACR #1 and ACR #n share access to a key with key ED "key 3".
• AGPs and, the ACRs within are organized in hierarchical trees and so aside from creating secure keys that keep sensitive data secure; an ACR can preferably also create other ACR entries that correspond to his key ID/partitions. These ACR children will have the same or less permissions as their father - creator and, may be given permissions for keys the father ACR himself created. Needless to add, the children ACRs get access permissions to any key that they create. This is illustrated in Fig. 6. Thus, all of the ACRs in AGP 120 were created by ACR 122 and two of such ACRs inherit from ACR 122 permission(s) to access to data associated with "key 3".
• Logging onto the SSA system is done by specifying an AGP and an ACR within the AGP.
• Every AGP has a unique ID (reference name), which is used as an index to its entry in the SSA database.
• the AGP name is provided to the SSA system, when the AGP is created. If the provided AGP name already exists in the system, the SSA will reject the creation operation.
• AGPs are used to administer restrictions on delegation of access and management permissions as will be described in the following sections.
• One of the functions served by the two trees in Fig. 6 is to administer the access by entirely separate entities, such as two different applications, or two different computer users.
• the SSA system when the SSA system is used in memory 10, this allows the memory system 10 to serve multiple applications simultaneously. It also allows the two applications to access two separate sets of data independently of one another (e.g.
• the data associated with "keys 3", “key X" and “key Z" for the application or user accessing via nodes (ACRs) in the tree in the top portion of Fig. 6 may comprise photographs.
• the data associated with "key 5" and "key Y” for the application or user accessing via nodes (ACRs) of the tree in the bottom portion of Fig. 6 may comprise songs.
• the ACR that created the AGP has the permission to delete it only when the AGP is empty of ACR entries
• An ACR in the SSA system describes the way the entity is permitted to log into the system. When an entity logs into the SSA system it needs to specify the ACR that corresponds to the authentication process it is about to perform.
• An ACR includes a Permissions Control Record (PCR) that illustrates the granted actions the user can execute once authenticated as defined in the ACR as illustrated in Fig. 5.
• PCR Permissions Control Record
• the host side entity provides all of the ACR data fields.
• an SSA system entity initiates the login process it needs to specify the ACR ID (as provided by the host when the ACR was created) that corresponds to the login method so that the SSA will set up the correct algorithms and select the correct PCR when all login requirements have been met.
• the ACR ID is provided to the SSA system when the ACR is created.
• the authentication algorithm specifies what sort of login procedure will be used by the entity, and what kind of credentials are needed to provide proof of user's identity.
• the SSA system supports several standard login algorithms, ranging from no procedure (and no credential) and password-based procedures to a two-way authentication protocols based on either symmetric or asymmetric cryptography.
• the entity's credentials correspond to the login algorithm and are used by the SSA to verify and authenticate the user.
• An example for credential can be a password/PIN-number for password authentication, AES-key for AES authentication, etc.
• the type/format of the credentials i.e. the PIN, the symmetric key, etc ..
• the SSA system has no part in defining, distributing and managing these credentials, with the exception of PKI based authentication where the device (e.g. flash card) can be used to generate the RSA key pair and the public key can be exported for certificate generation.
• the PCR shows what is granted to the entity after logging into the SSA system and passing the ACR' s authentication process successfully.
• This section of the PCR contains the list of partitions (using their IDs as provided to the SSA system) the entity can access upon completing the ACR phase successfully.
• the access type may be restricted to write-only or read-only or may specify full write/read access rights.
• the ACR#1 in Fig. 5 has access to partition #2 and not partition #1.
• the restrictions specified in the PCR apply to the SSA partitions and the public partition.
• the public partition can be accessed either by regular read and write commands to the device (e.g. flash card) hosting the SSA system, or by SSA commands.
• the device e.g. flash card
• SSA commands e.g. SR commands
• An ACR can preferably only restrict the regular read and write commands from accessing the public partition.
• ACRs in the SSA system can be restricted preferably only upon their creation. Once an ACR has the permission to read/write from/to the public partition, preferably it cannot be taken away.
• This section of the PCR contains the data associated with the list of key IDs (as provided to the SSA system by the host) the entity can access when the ACR policies have been met by the entity's login process.
• the key ID specified is associated with a file/files that reside in the partition appearing in the PCR. Since the key IDs are not associated with logical addresses in the device (e.g. flash card), when more than one partition is associated with a specific ACR, the files can be in either one of the partitions.
• the key IDs specified in the PCR can have each, a different set of access rights. Accessing data pointed to by key IDs can be restricted to write-only or read-only or may specify full write/read access rights.
• ACR Attributes Management (ACAM)
• ACAM actions that may be permitted in the SSA system are:
• a father ACR preferably cannot edit ACAM permissions. This would preferably require the deletion and recreation of the ACR. Also the access permission to a key ID created by the ACR can preferably not be taken away.
• An ACR may have the capacity to create other ACRs and AGPs.
• Creating ACRs also may mean delegating them some or all of the ACAM permissions possessed by their creator. Having the permission to create ACRs means having the permission for the following actions:
• the authentication method preferably cannot be edited once set by the creating ACR.
• the credentials may be altered within the boundary of the authentication algorithm that is already defined for the child.
• An ACR with the permissions to create other ACRs has the permission to delegate the unblocking permission to ACRs it creates (although it probably does not have the permission to unblock ACRs). The father ACR will place in the child ACR a reference to his unblocker.
• the father ACR is the only ACR that has the permission to delete his child ACR.
• An ACR deletes a lower level ACR that he created, then all ACRs spawned by this lower-level ACR are automatically deleted as well.
• An ACR is deleted then all the key IDs and partitions that it created are deleted.
• Passwords/PINs although set by the creator ACR, can be updated only by the ACR that includes them.
• a root ACR may delete itself and the AGP that it resides in.
• ACRs and their AGPs are assembled in hierarchical trees where the root AGP and the ACRs within are at the top of the tree (e.g. root AGPs 130 and 132 in Fig. 6). There can be several AGP trees in the SSA system though they are totally separated from one another.
• An ACR within an AGP can delegate access permissions to its keys to all ACRs within the same AGP that it is in, and to all the ACRs created by them.
• the permission to create keys preferably includes the permission to delegate access permissions to use the keys.
• Access - this defines the access permissions for the key i.e. Read, Write.
• Ownership - an ACR that created a key is by definition its owner. This ownership can be delegated from one ACR to another (provided that they are in the same AGP or in a child AGP). An ownership of a key provides the permission to delete it as well as delegate permissions to it.
• An ACR can delegate access permissions to partitions he created as well as other partitions he has access permissions to.
• the permission delegation is done by adding the names of the partitions and key IDs to the designated ACR' s PCR.
• Delegating key access permissions may either be by the key ID or by stating that access permission is for all of the created keys of the delegating ACR.
• An ACR may have a blocking counter which increments when the entity's ACR authentication process with the system is unsuccessful. When a certain maximum number (MAX) of unsuccessful authentications is reached, the ACR will be blocked by the SSA system.
• MAX maximum number
• the blocked ACR can be unblocked by another ACR, referenced by the blocked ACR.
• the reference to the unblocking ACR is set by its creator.
• the unblocking ACR preferably is in the same AGP as the creator of the blocked ACR and has the "unblocking" permission.
• An ACR may be configured with a blocking counter but without an unblocker ACR. hi this case, if this ACR get blocked it cannot be unblocked.
• the SSA system is designed to handle multiple applications and isolate the data of each one of them.
• the tree structure of the AGP system is the main tool used to identify and isolate application specific data.
• the root AGP is at the tip of an application SSA database tree and adheres to somewhat different behavior rules.
• Several root AGPs can be configured in the SSA system. Two root AGPs 130 and 132 are shown in Fig. 6. Obviously fewer or more AGPs may be used and are within the scope of this invention.
• Registering the device e.g. flash card
• the device e.g. flash card
• issue credentials of a new applications for the device are done through the process of adding new AGP/ ACR tree to the device.
• the SSA system supports three different modes of root AGP creation
• Open Any user or entity without requiring any sort of authentication, or users/entities authenticated through the system ACR (explained below), can create a new root AGP.
• the open mode enables creation of root AGPs either without any security measures while all data transfer is done on an open channel (i.e. in the secure environment of an issuance agency) or, through a secure channel established through the system ACR authentication (i.e. Over The Air (OTA) and post issuance procedures).
• OTA Over The Air
• the root AGP creation mode is set to Open, only the open channel option is available. 2. Controlled: Only entities authenticated through the System ACR can create a new root AGP. The SSA system cannot be set to this mode if system ACR is not configured.
• Method configuration lock command Used to disable the method configuration command and permanently lock the currently selected method.
• a root AGP When a root AGP is created, it is in a special initializing mode that enables the creation and configuration of its ACRs (using the same access restrictions that applied to the creation of the root AGP). At the end of the root AGP configuration process, when the entity explicitly switches it to operating mode, the existing ACRs can no longer be updated and additional ACRs can no longer be created
• root AGP Once a root AGP is put in standard mode it can be deleted only by logging into the system through one of its ACRs that is assigned with the permission to delete the root AGP. This is another exception of root AGP, in addition to the special initialization mode; it is preferably the only AGP that may contain an ACR with the permission to delete its own AGP, as opposed to AGPs in the next tree level.
• the system ACR may be used for the following two SSA operations:
• the System ACR creates the root ACR/AGP in the SSA. It has permission to add/change the root level until such time that the host is satisfied with it and blocks it. Blocking the root AGP essentially cuts off its connection to the system ACR and renders it temper proof. At this point no one can change/edit the root AGP and the ACRs within. This is done through an SSA command. Disabling creation of root AGPs has a permanent effect and cannot be reversed. The above features involving the system ACR are illustrated in Fig. 7. The system ACR is used to create three different root AGPs.
• the SSA command is sent from the host to block the root AGPs from the system ACR, thereby disabling the create-root-AGP feature, as indicated by the dotted lines connecting the System ACR to the root AGPs in Fig. 7. This renders the three root AGPs temper proof.
• the three root AGPs may be used to create children AGPs to form three separate trees, before or after the root AGPs are blocked.
• Issued is the process of putting identification keys by which the device can identify the host and vice versa. Identifying the device (e.g. flash card) enables the host to decide whether it can trust its secrets with it. On the other hand, identifying the host enables the device to enforce security policies (grant and execute a specific host command) only if the host is allowed to.
• Products that are designed to serve multiple applications will have several identification keys.
• the product can be "pre-issued” - keys stored during manufacturing before shipping, or "post issued” - new keys are added after shipping.
• the memory device e.g. memory card
• the memory device needs to contain some kind of master or device level keys which are being used to identify entities which are allowed to add applications to the device.
• the above described features enables a product to be configured to enable/disable post issuance.
• the post issuance configuration can be securely done after shipping.
• the device may be bought as a retail product with no keys on it in addition to the master or device level keys described above, and then be configured by the new owner to either enable further post issuance applications or disable them.
• system ACR feature provides the capability to accomplish the above objectives:
• - Memory devices with system ACR may be configured to disable the application adding feature, before or after applications have been added. Key ID list
• Key EDs are created per specific ACR request; however, in the memory system 10, they are used solely by the SSA system. When a key ID is created the following data is provided by or to the creating ACR:
• the ED is provided by the entity through the host and is used to reference the key and data that is encrypted or decrypted using the key in all further read or write accesses.
• Key ID Owner The ID of the ACR that is the owner. When a key ED is created the creator ACR is its owner. Key ED ownership may, however, be transferred to another ACR. Preferably only the key ED owner is allowed to transfer ownership of, and delegate, a key ID. Delegating access permission to the associated key, and revoking these rights can be administered either by the key ED owner or any other ACR assigned with delegation permissions. Whenever an attempt is made to exercise any one of these operations, the SSA system will grant it only if the requesting ACR is authorized.
• CEK This is the CEK used to cipher the content associated with or pointed to by the key ED.
• the CEK may be a 128 bit AES random key generated by the SSA system.
• MAC and IV values Dynamic information (message authentication codes and initiation vectors) used in the Chained Block Cipher (CBC) encryption algorithms.
• CBC Chained Block Cipher
• 'H' to the left of a step means the operation is performed by the host
• 'C means the operation is performed by the card.
• the host issues to the SSA in the memory device 10 a command to create System ACR (block 202).
• the device 10 responds by checking whether a System ACR already exists (block 204, diamond 206). If it already exists, then device 10 returns failure and stops (oblong 208). If it does not, then memory 10 checks to see if System ACR creation is allowed (diamond 210), and returns a failure status if not allowed (block 212).
• the device issuer does not allow the creation of a System ACR, such as in the case where the security features needed have been predetermined so that no System ACR is needed. If this is allowed, the device 10 returns OK status and waits for System ACR credentials from the host (block 214). The host checks the SSA status and whether the device 10 has indicated that the creation of a System ACR is allowed (block 216 and diamond 218). If creation is not allowed or if a system ACR already exists, the host stops (oblong 220). If the device 10 has indicated that the creation of a System ACR is allowed, the host issues a SSA command to define its login credential and sends it to the device 10 (block 222).
• the device 10 updates a System ACR record with the credential received and returns OK status (block 224).
• the host issues SSA command indicating the system ACR is ready (block 226).
• the device 10 responds by locking the System ACR so that it cannot be updated or replaced (block 228). This locks in the features of the system ACR and its identity for identifying the device 10 to the host.
• the procedure for creating new trees is determined by the way these functions are configured in the device. Fig 9 explains the procedures. Both the host 24 and the memory system 10 follow it. If adding new root AGP is disabled altogether, new root AGPs cannot be added (diamond 246). If it is enabled but requires a system ACR, the host authenticates through the system ACR and establishes a secure channel (diamond 250, block 252) prior to issuing the Create Root_AGP command (block 254). If system ACR is not required (diamond 248) the host 24 can issue the create root AGP command without authentication and proceed to block 254.
• system ACR does exist, the host may use it even if it is not required (not shown in the flow chart).
• the device e.g. flash card
• the newly created AGP and ACR in block 254 are now switched to Operational Mode so that the ACRs in such AGPs cannot be updated or otherwise changed, and no ACRs can be added to them (block 256).
• the system is then, optionally locked so that additional root AGPs cannot be created (block 258).
• the dotted line box 258 is a convention indicating that this step is an optional step. All the boxes in the flow charts of the figures of this application in dotted lines are optional steps. This allows the content owner to block the use of device 10 for other illicit purposes that may imitate a genuine memory device with legitimate content.
• ACRs other than the ACRs in the root AGP as described above
• An entity may attempt to enter through the host 24 by providing the entry point ACR identity, and the ACR with all the necessary attributes that it wishes to create (block 272).
• the SSA checks for a match to the ACR identity and whether the ACR with such identity has the permission to create an ACR (diamond 274). If the request is verified to be authorized, the SSA in device 10 creates an ACR (block 276).
• Fig. 11 shows two AGPs that illustrate a tree useful in security applications using the method of Fig. 10.
• the ACR with identity ml in the marketing AGP has the permission to create an ACR.
• the ACR ml also has the permission to use a key for reading and writing data associated with the key ID "Marketing Information" and data associated with the key ED "Price List”.
• Using the method of Fig. 10 it creates the Sales AGP with two ACRs: si and s2 with only read permission to the key for accessing pricing data associated with the key ID "Price List", but not to the key necessary for accessing data associated with the key ID "Marketing Information”.
• the ACR m2 has no permission to create ACRs, and has only read permission to the keys for accessing data associated with the key ID "Price List" and with the key ID "Marketing Information”.
• access rights may be delegated in the manner explained above where ml delegates rights to read pricing data to si and s2. This is particularly useful where large marketing and sales groups are involved. Where there are but one or a few sales people, there may be no need to use the method of Fig. 10. Instead, the access rights may be delegated, by an ACR to one at a lower or the same level within the same AGP, as illustrated in Fig. 12. First, the entity enters the tree for such AGP by specifying an ACR in the manner described above in the tree through the host (block 280). Next the host will specify the ACR and the rights to delegate to.
• the SSA checks the tree(s) for such ACR and whether the ACR has the permission to delegate rights to the specified another ACR (diamond 282). If it does, the rights are delegated (block 284); if not it stops. The result is illustrated in Fig. 13.
• the ACR ml in this case has the permission to delegate read permission to the ACR si, so that si will be able to use a key to access pricing data after the delegation. This may be performed if ml has the same or greater rights to access pricing data and the permission to so delegate. In one embodiment, ml retains its access rights after the delegation. Preferably access rights may be delegated under restricted conditions (rather then permanently) such as for a limited time, limited number of accesses, etc...
• the process for creating a key and key ED is illustrated in Fig. 14.
• the entity authenticates through an ACR (block 302).
• the entity requests the creation of a key with an ED specified by the host (block 304).
• the SSA checks and see if the ACR specified has the permission to do so (diamond 306). For example, if the key is to be used for accessing data in a particular partition, the SSA will check and see if the ACR may access such partition.
• the memory device 10 creates a key value associated with the key ED provided by the host (block 308), ands stores the key ED in the ACR, and the key value in its memory (either in the controller-associated memory or memory 20) and assigns rights and permissions according to information supplied by the entity (block 310) and modifies the PCR of such ACR with such assigned rights and permissions (block 312).
• the creator of the key has all available rights, such as read and write permissions, right to delegate and share with other ACRs in the same AGP or an ACR at a lower level, and the right to transfer ownership of the key.
• An ACR can change the permissions (or the existence altogether) of another ACR in the SSA system as illustrated in Fig. 15.
• An entity may enter a tree through an ACR as before; in one case the entity is authenticated and then it specifies an ACR (blocks 330, 332). It requests the deletion of a target ACR or the permission in a target ACR (block 334). If the ACR specified or the one active at such time has the right to do so (diamond 336), the target ACR is deleted, or the PCR of the target ACR is altered to delete such permission (block 338). If this is not authorized the system stops.
• an entity may attempt to enter at the target ACR (block 350) and finds that the authentication process fails, since the previously existing ACR ID is no longer present in the SSA, so that access rights are denied (diamond 352). Assuming that the ACR ID has not been deleted, the entity specifies an ACR (block 354) and the key ID and/or data in a particular partition (block 356), and the SSA then checks to see the key ID or partition access request is permitted according to the PCR of such ACR (diamond 358). If the permission has been deleted or has expired, then the request is again denied. Otherwise, the request is granted (block 360).
• the above process describes how access to protected data is managed by the device (e.g. flash card), regardless of whether the ACR and its PCR were just changed by another ACR or were so configured to begin with.
• the device e.g. flash card
• the SSA system is designed to handle multiple users, logged in concurrently. This feature requires that every command received by the SSA is associated with a specific entity and executed only if the ACR, used to authenticate this entity, has the permissions for the requested action.
• a session is established during the authentication process and assigned a session-id by the SSA system.
• the session-id is internally associated with the ACR used for logging into the system and is exported to the entity to be used in all further SSA commands.
• the SSA system supports two types of sessions: Open, and Secure sessions.
• the session type associated with a specific authentication process is defined in the ACR.
• the SSA system will enforce session establishment in a way similar to the way it enforces the authentication itself. Since the ACR defines the entity permissions, this mechanism enables system designers to associate secure tunneling either with accessing specific key IDs or invoking specific ACR management operations (i.e. creating new ACRs and setting credentials)
• Open session is a session identified with a session-id but without bus encryption, all commands and data are passed in the clear. This mode of operation is preferably used in a multi-user or multi-entity environment where the entities are not part of the threat model, nor is eavesdropping on the bus.
• the Open session mode enables the SSA system to allow access only to the information allowed for the currently authenticated ACRs.
• the Open session can also be used for cases where a partition or a key needs to be protected. However, after a valid authentication process, access is granted to all entities on the host. The only thing the various host applications need to share, in order to get the permissions of the authenticated ACR is the session-id. This is illustrated in Fig. 17A. The steps above the line 400 are those taken by the host 24. After an entity is authenticated (block 402) for ACRl, it requests access to a file associated with a key ID X in the memory device 10 (blocks 404, 406 and 408). If the PCR of the ACR 1 allows such access, device 10 grants the request (diamond 410). If not, the system returns to block 402.
• the memory system 10 identifies the entity issuing a command only by the assigned session id (and not the ACR credentials). Once the ACR 1 gains access to the data associated with the key IDs in its PCR, in an open session, any other application or user can access the same data by specifying the correct session ID which is shared between the different applications on the host 24.
• This feature is advantageous in applications where it is more convenient to the user to be able to log in only once, and be able to access all the data tied to the account through which the log in is performed for different applications.
• a cellular phone user may be able to access stored emails, and listen to stored music in memory 20 without having to log in multiple times.
• data not encompassed by the ACRl will not be accessible.
• the same cellular phone user may have valuable content such as games and photographs accessible through a separate account ACR2.
• This is data that he does not wish others who borrow his phone to access, even though he may not mind others accessing data available through his first account ACRl.
• Separating access to the data into two separate accounts while allowing access to ACRl in open session provides ease of use as well as affording protection of valuable data.
• the session id may be used as shown in Fig.
• the memory 10 then also stores the session ids of the active sessions.
• the entity in order to be able to access a file associated with key ID X, the entity will need to also provide a session id, such as session id "A" before it is allowed to access the file (blocks 404, 406, 412 and 414). In this manner, unless the requesting entity is aware of the correct session id, it cannot access the memory 10. Since the session id is deleted after the session is over and will be different for each session, an entity can gain access only when it has been able to provide the session number.
• the SSA system has no way to make sure that a command is really coming from the correct authenticated entity, other than by using the session number.
• the host application uses a secure session (a secure channel).
• the session-id is encrypted with the secure channel encryption (session) key and the security level is as high as the host side implementation. Terminating a session
• a session is terminated and, the ACR is logged off, in any one of the following scenarios:
• the entity issues an explicit end-session command.
• the SSA system verifies the integrity of the SSA database (which contains all the ACRs, PCRs, etc). hi addition data integrity services are offered for entity data through the key ID mechanism.
• Hash values are stored along side with the CEK and IV in the CEK record. Hash values are calculated and stored during write operation. Hash values are again calculated during read operations and compared with the values stored during the previous write operations. Every time the entity is accessing the key ID the additional data is concatenated (cryptographically) to the old data and the appropriate Hash value (for read or for write) updated.
• a data file associated with or pointed to by a key ID is written or read from the beginning to end. Any attempt to access portions of the file will mess it up since the SSA system is using a CBC encryption method and generates a hashed message digest of the entire data
• the SSA system provides a "dummy read” operation as well. This feature will stream the data through the encryption engines but will not send it out to the host. This feature can be used to verify data integrity before it is actually read out of the device (e.g. flash card).
• the SSA system will enable external entities to make use of the internal random number generator and request random numbers to be used outside of the SSA system. This service is available to any host and does not require authentication.
• the SSA system will enable external users to make use of the internal
• RSA key pair generation feature and request an RSA key pair to be used outside of the SSA system. This service is available to any host and does not require authentication.
• a list of credentials for entities, authentication methods, the maximum number of failed attempts, and the minimum number of credentials needed to unblock may be entered into a database stored in controller 12 or memory 20, which relates such credential requirements to the policies (read, write access to keys and partitions, secure channel requirement) in the database carried out by the controller 12 of memory 10.
• Also stored in the database are constraints and limitations to the access to keys and partitions.
• some entities e.g. system administrator
• Other entities may be on a black list, and their attempts to access any information will be blocked.
• the limitation can be global, or key and/or partition specific.
• Password-protect means that a password needs to be presented to access the protected area. Unless it cannot be more than one password then passwords could be associated with different rights such as read access or read/write access.
• Password protect means that the device (e.g. flash card) is able to verify a password provided by the host i.e. the device also has the password stored in device managed secured memory area. Issues and limitations
• Passwords are subject to replay attack. Because the password does not change after each presentation it can be identically resent. It means that password as is must not be use if the data to be protected are valuable, and the communication bus is easily accessible.
• Password could protect access to stored data but should NOT be used to protect data (not a key)
• a session key based secure communication channel can be use to send the password.
• Fig. 19 is a flow chart illustrating authentication using a password.
• the entity sends in an account id and password to system 10 (e.g. flash memory card).
• system 10 e.g. flash memory card.
• the system checks to see if the password matches that in its memory. If it matches, authenticated status is returned. Otherwise, the error counter is incremented for that account, and the entity is asked to re-enter an account id and password. If the counter overflows, the system return status that access is denied.
• Fig. 20 is a Flow Chart illustrating authentication using a challenge/response type method.
• the entity sends in an account id and requests a challenge from system 10.
• System 10 generates a random number and presents it to the host.
• the host computes a response from the number and sends it to the system 10.
• System 10 compares the response to the value stored. The remaining steps are similar to those in Fig. 19 for determining whether to grant access.
• Fig. 21 is a Flow Chart illustrating authentication using another challenge/response type method.
• Fig. 21 differs from that in Fig. 20 in that, in addition to requiring the host to be authenticated by the system 10, it also requires the system 10 to be authenticated by a challenge/response where system 10 also requests a challenge from the host and returns a response to be checked by the host.
• Fig. 22 is a Flow Chart illustrating authentication using another challenge/response type method.
• the host sends a challenge to system 10, which computes a response that is checked by the host for a match with its record of system 10.
• Symmetric key algorithm means that the SAME key is used on both sides to encrypt and decrypt. It means that the key must have been pre-agreed prior to communicating. Also each side should implement the reverse algorithm of each other i.e. encrypt algorithm on one side and decrypt on the other. Both sides do not need to implement both algorithms to communicate.
• Symmetric key authentication means that device (e.g. flash card) and host share the same key and have the same cryptographic algorithm (direct and reverse e.g. DES and DES-I). Symmetric key authentication means challenge-response (protect against replay attack). The protected device generates a challenge for the other device and both compute the response. The authenticating device sends back the response and the protected device check the response and validate authentication accordingly. Then rights associated with authentication can be granted.
• Authentication could be:
• the device e.g. flash card
• the device authenticates the outside world i.e. the device validates credentials of a given host or application
• the host application authenticates the device (e.g. flash card) i.e. host checks if device is genuine for its application.
• Symmetric key are usually combined with diversification using a master key
• Mutual authentication uses challenge from both side to ensure challenge is a real challenge
• Symmetric key cryptography is also used for encryption because it is a very efficient algorithm i.e. it does not need a powerful CPU to handle cryptography.
• Both devices have to know the session key used to secure the channel (i.e. encrypt all outgoing data and decrypt all incoming data).
• This session key is usually established using a pre-shared secret symmetric key or using PKI.
• Symmetric key can also be used to sign data.
• the signature is a partial result of the encryption. Keeping the result partial allows to sign as many time as needed without exposing the key value.
• Symmetric algorithms are very efficient and secure but they are based on a pre-shared secret.
• the issue is securely share this secret in a dynamic manner and possibly to have it random (like a session key).
• the idea is that a shared secret is hard to keep safe in a long term and is almost impossible to share with multiple people.
• Asymmetric key algorithm is commonly referred Public Key cryptograph. It is a quite complex and usually CPU intensive mathematical implementation. It has been invented to solve the issues of key distribution associated with symmetric key algorithms. It also provides signing capabilities used to ensure data integrity.
• Asymmetric key algorithm uses a key which has private and public elements respectively referred as private key and public key. Both private key and public key are mathematically linked together. The public key can be shared whereas the private has to remain secret. As for the keys, asymmetric algorithm uses two mathematical functions (one for the private key and one for the public key) to provide wrap and unwrap or sign and verify.
• Key exchange becomes very simple using PK algorithm.
• the device sends its public key to the other device.
• the other device wraps its secret key with the public key and returns the encrypted data to the first device.
• the first device uses its private key to unwrap the data and retrieve the secret key which is now known to both sides and can be used to exchange data. Because the symmetric key can be exchanged that easily it is usually a random key. Signature
• the Private key is used to sign the data.
• the public key (freely available) allows to verify the signature.
• Authentication usually uses signature: a challenge is signed and returned for validation
• the public part of the key is used for verification. Because anyone can generate a key pair, there is a need to certify the owner of the public key in order to prove that this is the right person using the correct key.
• Certification authority provides certification and will include the public key in a signed certificate. The certificate is signed by the authority itself. Then using a public key to verify a signature means that the authority that issued the certificate containing that key is trusted and that one is able to verify that the certificate has not been hacked i.e. that the certificate hash signed by the authority is correct; meaning that the user has and trusts the authority public key certificate.
• Authentication in a device means that the device is loaded with trusted root certificates and that the device is able to verify the challenge response as well as the certificate signed hash.
• PK algorithm is not used to encrypt large amounts of data because it is too CPU intensive, but is usually used to protect a randomized encryption / decryption key generated to encrypt the content.
• SMIME Secure email
• the SSA system commands are passed to a memory card using standard (for the relevant form factor protocol) write and read commands. Therefore, from the host point of view, sending an SSA command really means writing data to a special file, on the memory device, used as the buffer file. Getting information from the SSA system is done via reading data from the buffer file. The host application must make sure data is always written and read from the first LBA of the buffer file. Managing the buffer files in the host OS is beyond the scope of this specification.
• the first data block of every write commands is scanned for a pass through signature. If found, the data is interpreted as an SSA commands. If not found, the data is written to the designated address.
• SSA application specific write commands may include multiple sector transfer where the first sector holds the required signatures and command's arguments and the rest of the data blocks hold the relevant data if any.
• Table ... defines the format of the first block (data blocks are always 512 bytes as used in standard OS file s stems of an SSA command.
• a read command is used to initiate the actual data transfer from the card to the host.
• the read command must use the same LBA address the previous write command used. This is the only indication to the card that the host is trying to get the SSA data, previously requested.
• the write/read command pairs must be carefully synchronized.
• the next session defines how sequence errors are handled and recovered from.
• the SSA system supports multiple host side users, which may be concurrently logged on. Each user is expected to, independently and asynchronously, initiate write/read command pairs hence, not requiring any special behavior of the host OS. From the card point of view these individual pairs are identified by the LBA address used in the write half of the sequence. From the host point of view it means each user must use a different file buffer.
• Table 2 provides a general overview of the SSA commands.
• the command name column provides a basic description of the commands usage and also index to the detail description of the command.
• the command op-code is the actual value used in the SSA command.
• Argument length (Arg Len) column defines the size of the argument field of the command (a value of zero means no argument).
• Data length is the size of the command data in the additional data blocks associated with the commands.
• a value of zero means no data
• a value of "Var" means the command has variable data sizes and the actual size is specified in the command itself. For fixed sized data commands this column stores the size of data size.
• Data direction can be either blank if the command has no data (meaning that the command arguments as specified in Table 1 all fit in the space between byte 76 and byte 511 - beyond this lays the data payload accompanying the command sector),
• Create system ACR builds a system ACR entry in the SSA database. Once the entry is created the credentials can be configured according to the specified login algorithm. Finally the CREATE_SYSTEM_ACR_DONE command is used to terminate the sequence and render the system ACR active.
• Create system ACR command will be rejected if an ACR entry already exists or create system ACR feature is disabled.
• System ACR may be configured only with a subset of the available login modes (refer to section 1.3.2 for details). If an invalid mode is used the command will be rejected.
• Command arguments are given in Table 3. The byte offset is relative to the start of the command argument LBA (see section 1.1.1). Argument length is given in byte units. Argument name defines the purpose of the argument and can be used as index to the detailed ar ument descri tion.
• This command is sent only after the system ACR creation began. In any other time the command will be rejected. Sending this command ends the system ACR creation and will leave the ACR with the current configuration forever. There are no arguments for this command.
• a session ID will be created and used for the creation sequence.
• the session ID is available when requesting system- command return status right after the system ACR login sequence is done.
• Creating a root AGP without logging in to the system ACR first does not require a session ID.
• Table 8 reviews the commands arguments. When not using the system ACR the Session ID field is left with NULL (NA). AGP name/ID is preceded by the bytes number of its len th.
• This command is delivered when the root AGP is done - meaning all of the ACRs in the AGP are created. This command will lock the AGP so no more ACRs can be created.
• This command renders SET_ROO_AGP_CREATION_MODE command inoperable and it will be rejected by the SSA. This command has no arguments.
• This command can be sent only by the ACR creator to update the child ACR.
• ACRs residing in the root AGP can't be updated, as they haven't a father ACR.
• This command can be sent only by the ACR creator to delete the child ACR.
• ACRs residing in the root AGP have the ability to delete themselves.
• Command Structure This command is issued when a host user wishes to use the SSA system through one of the ACRs. The command will start the login/authentication process.
• This command is issued when the host user wishes to terminate a working session with the SSA system.
• the command ends all of the user activity for the current login session. After this command the host user will need to start the login process again to be able to execute further actions with the SSA system.
• This status command can be sent to get the return status of the previous command sent.
• the status deals with the command process and SSA system state.
• the system query command reads SSA information that is in the scope of the ACR that is logged in.
• Command Structure :
• the command sends the actual ACR password to be verified by the SSA.
• Sending the Command Status command (22) will, the host will be able to read the command status and upon command completion the status of the authentication process - PASS/FAIL.
• Password and PIN phrases are 20 bytes long and are of binary value to the SSA s stem. An hrase shorter then 20 b tes must be added with '0'.
• a root AGP can be created either via the system ACR (which requires to execute a login sequence to the system ACR) or forgo the secure channel and skip the system ACR authentication process.
• Command SSA_CREATE_ROOT_AGP_CMD [3] is sent with the root AGP' s identity.
• SSA_CMD_STATUS_CMD [22] This command can be followed by SSA_CMD_STATUS_CMD [22] to make sure that the SSA did not reject the command and that it was done without an error.
• SSA_ROOT_AGP_CREATION_DONE_CMD [4] command will be sent.
• the user To create an AGP, the user must first login to the SSA by executing the login command sequence shown in 1.3.13.1.
• the AGP must be created before creating new group of ACRs.
• the AGP is created by sending command SSA CREATE_AGP_CMD [5] with the AGP Name/ID.
• the user To create an ACR, the user must first login to the SSA by executing the login command sequence shown in 1.3.13.1. Also, there must be an AGP were the new ACR belong. Then the user sends command SSA_CREATE_ACR_CMD [7] with all of the new ACR data (name, AGP, login methods...etc.). To verify that CMD [7] was received and executed without an error the user sends
• SSA_CMD_STATUS_CMD [22] and reads the status of the previous sent command.
• the user is done creating the ACR he can proceed with other SSA operations or logout from the SSA system.

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