Parallel Secret Salt Generation and Authentication for Encrypted Communications

Abstract

In a method for facilitating encrypted communications between a transmitting system having a unique identifier and a receiving system, a key generation system generates at least one encryption master key for use with the unique identifier and an encryption algorithm to generate a unique encryption key for the transmitting system. The key generation system also generates a shared secret master key for use with the unique identifier and a second encryption algorithm to generate a shared secret value. The at least one encryption master key and the shared secret master key are then stored in an encryption information database. The key generation system transmits the at least one encryption master key and the shared secret information to the transmitting system, and transmits the at least one encryption master key, the shared secret master key, and the unique identifier to the receiving data processing system.

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE This disclosure relates generally to cryptographic techniques, and more particularly to systems and methods for cryptographic authentication of communications between data processing systems. (CROSS-REFERENCE TO RELATED APPLICATIONS)

[0002] This application claims priority to U.S. Patent Application No. 17 / 890,628, filed August 18, 2022, the disclosure of which is incorporated herein by reference in its entirety. [Background technology]

[0003] Data security and transaction integrity are critical to businesses and consumers. This need continues to grow as electronic transactions account for an ever-increasing proportion of commercial activity. While data encryption algorithms have improved communication security, vulnerabilities still exist. For example, symmetric encryption techniques require that sending and receiving systems share information and software with each other. The process of communicating such shared information can itself be subject to vulnerabilities.

[0004] Therefore, there is a need to increase the integrity of information shared between communication partners used to encrypt transactions and other important communications. Summary of the Invention

[0005] An exemplary aspect of the present invention provides a card comprising a data processor, a communications interface configured for contact or contactless communication with an intermediate processing device, and a card memory. The card memory stores a shared secret master key, a unique card identifier, and a message encryption application. The message encryption application includes instructions for the data processor to generate a shared secret value using the unique card identifier and the shared secret master key. The application further includes instructions for generating a message authentication code using the shared secret value, encrypting at least a portion of the message content using a first session key to generate encrypted message content, and encrypting the message authentication code. The application also includes instructions for transmitting a message including the encrypted message content and the encrypted message authentication code to the intermediate processing device for retransmission to a receiving communication processing system.

[0006] Another aspect of the present invention provides a method for facilitating symmetric encrypted communications between a transmitting data-processing system and a receiving data-processing system having associated unique identifiers. The method includes generating, by a key-generation data-processing system, at least one encrypted master key. Each encrypted master key is configured for use with the unique identifier and a first encryption algorithm to generate a transmitting-system-unique encryption key. The method further includes generating, by the key-generation data-processing system, a shared secret master key. The shared secret master key is configured for use with the unique identifier and a second encryption algorithm to generate a shared secret value. The method still further includes storing, by the key-generation data-processing system, the at least one encrypted master key and the shared secret master key in association with the unique identifier in an encryption information database. The method also includes transmitting, by the key-generation data-processing system, the at least one encrypted master key and the shared secret information to the transmitting data-processing system, and transmitting, by the key-generation data-processing system, the at least one encrypted master key, the shared secret master key, and the unique identifier to the receiving data-processing system.

[0007] Another aspect of the present invention provides a method for authenticating a message transmitted by a sending data-processing system having an associated unique identifier, the transmitted message including encrypted content and an encrypted message authentication code. The method includes operations performed by a receiving data-processing system including receiving the transmitted message, determining a unique identifier, and retrieving an encryption information record for the sending data-processing system. The encryption information record includes a shared secret master key. The method includes further operations by the receiving data-processing system including decrypting the encrypted message authentication code, generating a shared secret value using the unique identifier and the shared secret master key, and generating a comparison message authentication code using the shared secret value. The method also includes comparing the comparison message authentication code with the decrypted message authentication code by the receiving data-processing system to determine a message authentication result. [Brief explanation of the drawings]

[0008] The present invention can be more fully understood by reading the following detailed description in conjunction with the accompanying drawings, in which like reference numerals are used to designate like elements and in which:

[0009] [Figure 1] 1 is a schematic diagram of a data transmission system that can be used to implement embodiments of the present invention; [Figure 2] 1 is a schematic diagram of a data transmission system that can be used to implement embodiments of the present invention; [Figure 3] 1 is a schematic diagram of a transaction card communication system according to one embodiment of the present invention. [Figure 4] FIG. 1 is a schematic diagram of a transaction card data processing system that can be used to implement embodiments of the present invention. [Figure 5] 1 is a schematic diagram of a user device that can be used to implement embodiments of the present invention. [Figure 6] 1 is a schematic diagram of a transaction processing machine that can be used to implement embodiments of the present invention; [Figure 7] 1 is a schematic diagram of a card issuer processing system according to one embodiment of the present invention; [Figure 8] 1 is a schematic diagram of a card message processing system according to one embodiment of the present invention; [Figure 9] FIG. 2 is a sequence diagram illustrating a series of operations in facilitating authenticatable encrypted communications according to one embodiment of the present invention. [Figure 10] 1 is a flowchart of operations in a method for facilitating encrypted message authentication in accordance with one embodiment of the present invention. [Figure 11] 3 is a flowchart of operations in a method for constructing an authenticatable encrypted message according to one embodiment of the present invention. [Figure 12] 4 is a flowchart of operations in a method for authenticating an encrypted message according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] While the invention is described in connection with particular embodiments and manufacturing environments, it will be understood that the invention is not limited to these embodiments and environments. On the contrary, various alternatives, modifications, and equivalents are contemplated as being within the spirit and scope of the invention as described.

[0011] When using symmetric cryptographic algorithms, such as encryption algorithms, hash-based message authentication code (HMAC) algorithms, and block cipher-based message authentication code (CMAC) algorithms, it is important that the key(s) used remain secret between the party that initially processes the data being protected and the party that receives and further processes the data. It is also important that such values ​​are used infrequently. Each time a key or salt is used, it provides an attacker with an additional sample of the data processed by the cryptographic algorithm. The more data an attacker obtains that has been processed with the same key or salt, the greater the chance that the attacker will be able to discover these secret values.

[0012] Additional protection may be provided by the use of a message authentication code generated at least in part based on a secret value (often referred to herein as a salt or secret salt) that may be included in the encrypted message. Similar to the information needed to generate a session key or a key used in a symmetric cipher, the secret value used to create a MAC must be shared between the sender and receiver. Typically, this implies persistent or long-term storage and association of the shared value in each of the two systems. This also means that at some point the shared value must be transmitted from one of the communicating participants to the other, or from a third-party administrative entity to both participants. Such transmission provides a potential point of weakness before any encrypted message is passed between the sender and receiver.

[0013] Exemplary embodiments of the present invention provide systems and methods for symmetric cryptographic communications that incorporate message authentication using a shared secret value that can be dynamically generated by either or both of the sending and receiving systems. This not only provides the security of not maintaining the secret value in memory, but also offers the advantage of being able to securely transmit information that can be used to generate the secret value to either or both systems without having to transmit the shared value itself. This has particular value when one of the two systems includes or is closely associated with a system configured for generating and controlling the secret value. A particular example of this type of scenario is when one of the two communication processing systems is incorporated into a transaction card that is programmed and issued by a card issuing institution, and the second communication processing system is part of the transaction processing system.

[0014] 1, a data transmission system 100 according to an exemplary embodiment may include a transmitting or sending data processing system 110 and a receiving or recipient data processing system 120 that communicate with each other and with one or more servers 150 via a network 130. Processing systems 110, 120 may be or include any server, network appliance, personal computer (PC), workstation, mobile processing device such as a smartphone, smart pad, handheld PC, or personal digital assistant (PDA), or any network-enabled processor computer system or device, including, but not limited to, a card-mounted microprocessor capable of direct or indirect network communication.

[0015] Network 130 may be or may include a wireless network, a wired network, or any combination of wireless and wired networks, and may be configured to connect one or more transmission systems 110 and one or more receiving systems 120 to server 150. Network 130 may include, for example, one or more of an optical fiber network, a passive optical network, a cable network, an Internet network, a satellite network, a wireless LAN, Global System for Mobile Communications (GSM), Personal Communications Services (PCS), a personal area network, a wireless application protocol (WAP), multimedia messaging service (MMS), enhanced messaging service (EMS), short message service (SMS), a time division multiplexing (TDM)-based system, a code division multiple access (CDMA)-based system, D-AMPS, Wi-Fi, fixed wireless data, IEEE 802.11b, 802.15.1, 802.11n and 802.11g, Bluetooth, near field communication (NFC), radio frequency identification (RFID), Wi-Fi, and / or the like.

[0016] Additionally, network 130 may include a global network such as, but not limited to, telephone lines, optical fiber, IEEE Ethernet 902.3, a wide area network (WAN), a wireless personal area network, a local area network (LAN), or the Internet. Additionally, network 130 may support an Internet network, a wireless communication network, a cellular network, or the like, or any combination thereof. Network 130 may further include one network or any number of networks of the above exemplary types, operating as a standalone network or in cooperation with one another. Network 130 may utilize one or more protocols of one or more network elements communicatively coupled thereto. Network 130 may translate one or more protocols of network devices to and from other protocols. While network 130 is shown as a single network, it should be understood that, according to one or more examples, network 130 may include multiple interconnected networks, such as the Internet, a service provider network, a cable television network, an enterprise network such as a credit card association network, and a home network.

[0017] A network-enabled computer system used to perform methods contemplated by the present invention may execute one or more software applications to, for example, receive data as input from entities accessing the network-enabled computer system, process the received data, transmit data over the network, and receive data over the network. One or more network-enabled computer systems may also include one or more software applications for sending notifications to account holders or other users. It will be understood that the depiction of FIG. 1 is merely an example, and that the functions and processes described herein may be performed by any number of network-enabled computers. While the illustrated system 100 may have only a single instance of certain components, it will also be understood that multiple instances of these components may be used. System 100 may also include other devices not shown in FIG. 1.

[0018] In some examples, one or more transmission systems 110 and one or more receiving systems 120 may be configured to communicate with each other and / or with server 150 without traversing network 130. For example, communication between transmission system 110 and receiving system 120 and / or server 150 may occur via at least one of near field communication, Bluetooth, radio frequency identification, Wi-Fi, and / or the like. In some examples, either or both of transmission system 110 and receiving system 120 may comprise multiple devices capable of communicating with each other via network 130, via another network, or via near field communication Bluetooth, radio frequency identification, Wi-Fi, and / or the like.

[0019] In a typical usage scenario of the system 100, a sender and a receiver may wish to exchange data (e.g., original confidential data) via their respective systems 110 and 120. While the following examples refer specifically to two systems 110 and 120, it will be understood that additional transmitting and receiving systems may be involved, and that the roles of transmitting and receiving may be reversed in some cases. However, the primary requirement for participation is that each party share a secret master key that can be used to generate symmetric encryption keys. In some examples, the transmitting system 110 and the receiving system 120 may be provisioned with the secret master key. It will be understood that any other party or device capable of generating or provided with a symmetric encryption key can perform the functions of the transmitting system 110 or the receiving system 120. However, in typical examples, the symmetric encryption key is a session key that is kept secret from all parties other than the transmitting system 110 and the receiving system 120 involved in the secure data exchange.

[0020] In the method of the present invention, transmitting system 110 and receiving system 120 may also need to maintain or generate a shared secret value that can be used to generate a message authentication code. As discussed in more detail below, the shared secret value may, in some embodiments, be dynamically generated by one or both systems using a shared secret master key.

[0021] To prepare for an encrypted transmission, the transmission system 110 may be configured to establish a secret session key using a secret master key using an appropriate symmetric encryption algorithm. The symmetric algorithm used may include any symmetric encryption algorithm capable of generating diversified symmetric keys of the desired length. Non-limiting examples of symmetric algorithms may include symmetric encryption algorithms such as 3DES or AES128, symmetric HMAC algorithms such as HMAC-SHA-256, and symmetric CMAC algorithms such as AES-CMAC. It will be appreciated that if the output of the selected symmetric algorithm does not produce a sufficiently long key, techniques such as processing multiple iterations of the symmetric algorithm with different input data and the same master key can produce multiple outputs that can be combined as necessary to generate a key of sufficient length.

[0022] In some embodiments, additional parameters available to both transmitting system 110 and receiving system 120 may be used in constructing the shared symmetric session key. One example is a counter that is updated each time a communication is encrypted and transmitted from transmitting system 110 to receiving system 120. In some embodiments, the counter or other parameter may be included in the encrypted transmission and / or in an unencrypted attachment to the encrypted transmission.

[0023] The transmitting system 110 may be configured to use the constructed symmetric encryption session key to process some or all of the set of information for transmission to the receiving system 120. For example, the transmitting system 110 may encrypt a secret portion of the data using a symmetric encryption algorithm and the session key, with the output including the encrypted set of information. The transmitting system 110 may then transmit a message including the encrypted set of information. The message may also include unencrypted information, which may include, for example, information identifying the transmitting system and / or information regarding the nature of the encrypted set of information. In certain embodiments, additional communication parameters (e.g., a counter) may also be included.

[0024] In certain embodiments, the sensitive data portion encrypted using the session key may include a message authentication code generated using a shared secret value. In some embodiments, the transmission system 110 may be provisioned with an assigned shared secret value, which may be stored in memory included in or accessible by the transmission system 110. The transmission system 110 may be configured to retrieve the stored shared secret value from memory when constructing a message for transmission to the receiving system 120. The shared secret value may then be used as a salt value in any known cryptographic algorithm to generate the message authentication code. In some embodiments, the transmission system 110 may be provisioned with a shared authentication key that can be used with the shared secret value in a cryptographic algorithm to generate the message authentication code. In other embodiments, the transmission system may instead be provisioned with a shared authentication master key that can be used to dynamically generate a shared authentication key as needed. The resulting shared authentication key may then be used with the shared secret value in a cryptographic algorithm to generate the message authentication code. One or more other shared or determinable communication parameters (e.g., the counter described above) may be used to generate the shared authentication key, the message authentication code, or both.

[0025] In some embodiments, the transmission system 110 is not provided with a static shared secret value, but instead is provided with a shared secret master key that can be used to dynamically generate shared secret values ​​as needed. The shared secret master key may be included in the transmission system 110 at the time the message is constructed or may be stored in memory accessible by the transmission system 110. At such time, the transmission system 110 may retrieve the shared secret master key and combine it with one or more fixed parameters (e.g., a fixed identifier or account associated with the transmission system 110) and / or one or more variable parameters (e.g., an encrypted transmission counter) in an encryption algorithm to generate a shared secret value. The resulting shared secret value may then be used to construct a message authentication code as described above.

[0026] Once generated, the message authentication code may be added to the secret data portion of the message to be transmitted before encrypting the secret data portion with the symmetric key. Alternatively, the message authentication code may be encrypted separately to generate a message authentication code ciphertext that may be added to the message before transmission. The transmitting system 110 may then transmit the message, including the encrypted and unencrypted information, to the receiving system 120.

[0027] The receiving system 120 may be configured to receive and process messages transmitted by the transmitting system 110. This may include first processing the unencrypted information, which may include sufficient information for the receiving system 120 to identify the transmitting system 110, as discussed above. This may also include deriving one or more communication parameters, which may be included for use in decrypting the encrypted message information. In particular embodiments, the receiving system 120 may be configured to determine a symmetric session key used to encrypt the encrypted message information. As discussed above, the receiving system 120 may be provisioned with the same secret master key as the transmitting system. Thus, the receiving system 120 may be configured to use the same symmetric encryption algorithm as the transmitting system to establish a secret session key using the secret master key. In embodiments in which additional parameters are used in constructing the session key, the receiving system may also be configured to determine such parameters. In some embodiments, one or more such parameters may be included in the unencrypted portion of the received message. In other embodiments, parameters such as an encrypted communication counter may be determined in parallel by the receiving system 120.

[0028] The receiving system 120 may be further configured to decrypt the encrypted portion of the message using the constructed symmetric encryption session key. In embodiments in which a message authentication code is included as an accompanying ciphertext, the receiving system 120 may also separately decrypt this ciphertext. In either case, the receiving system 120 may be further configured to authenticate the received message using the decrypted message authentication code. To accomplish this, the receiving system 120 may look up or generate a shared secret value associated by the receiving system with the transmitting system 110. In some embodiments, the receiving system 120 may have a static shared secret value associated with the transmitting system's 110 identity or an account associated with the transmitting system. In such embodiments, the receiving system 120 may use the identity provided in the received message to look up the shared secret value from a database stored on or accessible by the receiving system 120. In other embodiments, the receiving system 120 may instead be required to generate the shared secret value using a copy of a shared secret master key. In such embodiments, the receiving system 120 may use the transmitting system identity to look up the shared secret master key rather than the shared secret itself. The receiving system 120 can then use the shared secret master key to generate the shared secret value in the same manner as the transmitting system 120 .

[0029] The resulting shared secret value may then be used as a salt value to generate a confirmatory message authentication code using the same encryption algorithm used by the transmitting system 110. In some embodiments, the receiving system 120 may retrieve from storage a shared authentication key that can be used with the shared secret value in a cryptographic algorithm to generate the confirmatory message authentication code. In other embodiments, the receiving system 120 may instead retrieve a shared authentication master key associated with the transmitting system 110 or with an account associated with the transmitting system 110. The shared authentication master key can then be used to generate the shared authentication key. The resulting shared authentication key can then be used with the shared secret value in a cryptographic algorithm to generate the confirmatory message authentication code. Depending on the embodiment, one or more other shared or determinable communication parameters (e.g., the counter described above) may be used to generate the shared authentication key, the confirmatory message authentication code, or both. Once generated, the confirmatory message authentication code may be compared to the decrypted message authentication code to authenticate the message.

[0030] 2, a data transmission system 200 according to an exemplary embodiment can include a transmitting or sending data processing system 210 and a receiving or receiving data processing system 220 that communicate with each other and with one or more servers 250 over a network 230. System 200 also includes a key generation and control system 240 configured for communication over network 230. The transmitting and receiving data processing systems 210, 220 can each be or include any server, network appliance, personal computer (PC), workstation, mobile processing device such as a smartphone, smart pad, handheld PC, or personal digital assistant (PDA), or any network-enabled processor computer system or device, including, but not limited to, a card-mounted microprocessor capable of direct or indirect network communication.

[0031] Network 230 may be or may include a wireless network, a wired network, or any combination of wireless and wired networks, and may be configured to connect one or more transmission systems 210 and one or more receiving systems 220 to server 250. Network 230 may include, for example, one or more of an optical fiber network, a passive optical network, a cable network, an Internet network, a satellite network, a wireless LAN, Global System for Mobile Communications (GSM), Personal Communications Services (PCS), a personal area network, a wireless application protocol (WAP), multimedia messaging service (MMS), enhanced messaging service (EMS), short message service (SMS), a time division multiplexing (TDM)-based system, a code division multiple access (CDMA)-based system, D-AMPS, Wi-Fi, fixed wireless data, IEEE 802.11b, 802.15.1, 802.11n and 802.11g, Bluetooth, near field communication (NFC), radio frequency identification (RFID), Wi-Fi, and / or the like.

[0032] Additionally, network 230 may include a global network such as, but not limited to, telephone lines, optical fiber, IEEE Ethernet 902.3, a wide area network (WAN), a wireless personal area network, a local area network (LAN), or the Internet. Additionally, network 230 may support an Internet network, a wireless communication network, a cellular network, or the like, or any combination thereof. Network 230 may further include one network or any number of networks of the above exemplary types, operating as a standalone network or in cooperation with one another. Network 230 may utilize one or more protocols of one or more network elements to which they are communicatively coupled. Network 230 may translate one or more protocols of network devices to or from other protocols. While network 230 is shown as a single network, it should be understood that, according to one or more examples, network 230 may include multiple interconnected networks, such as the Internet, a service provider's network, a cable television network, an enterprise network such as a credit card association network, and a home network.

[0033] In some examples, one or more transmitting systems 210 and one or more receiving systems 220 may be configured to communicate with each other, key generation and control system 240, and / or server 250 without traversing network 230. For example, key generation and control system 240 may be configured to communicate with sending data processing system 210 via communication link 232, which may be or include one or more of a private network, near field communication, Bluetooth, radio frequency identification, Wi-Fi, etc.

[0034] In various embodiments, the transmitting and receiving data processing systems 210, 220 may be similar to those described above with respect to data transmission system 100. In particular, the transmitting data processing system 210 and the receiving data processing system 220 may each be configured to look up or generate a shared encryption key that can be used to generate a shared session key for encrypting and decrypting message content for transmission over network 230. Additionally, the transmitting data processing system 210 and the receiving data processing system 220 may each be configured to look up or generate a shared secret and to look up and generate a shared authentication key that can be used to generate a message authentication code.

[0035] However, in system 200, some or all of the master keys used to generate parameters specific to the generation of a shared session key for a particular communication may be generated and shared by key generation and control system 240. In an exemplary embodiment, key generation and control system 240 may be configured to generate one or more of an encryption master key, a shared secret master key, and an authentication master key. Each of these may be associated with an identification for transmission system 210 or an account associated with transmission processing system 210. In some embodiments, any or all of these keys may then be transmitted to transmission processing system 210, which stores them for future use in generating encrypted communications. However, in some embodiments, key generation and control system 240 may generate a shared secret using the shared secret master key and the transmission system identifier, which is then transmitted to or stored directly in memory within transmission system 210. In particular embodiments, key generation and control system 240 may communicate one or more master keys and / or shared secrets to transmission data processing system 210 via private communication link 232. In some examples, this may be accomplished during the system provisioning process. In some embodiments, key generation and control system 240 may associate each master key with multiple transmitting data processing systems 210 and their unique identifiers. In this manner, a single shared secret master key may be combined with any one of multiple transmission system identifiers to generate a transmission system-specific shared secret.

[0036] The key generation and control system 240 may transmit any or all of the encryption master key, the shared secret master key, and the authentication master key, along with the identification information of the transmitting data processing system 210, over the network 230. The receiving data processing system(s) 220 may then store one or more keys and the identification information in accessible data storage. In a particular example, the key generation and control system 240 may transmit a copy of the shared secret master key and an identifier of the transmitting data processor to the receiving data processor 220, which may place them in storage. Upon receiving a message with encrypted information from the transmitting system 210, the receiving system 220 may be configured to generate a session key, decrypt the encrypted portion of the message, retrieve the shared secret master key, and use it together with the identifier (or other identifying information, as needed) to generate a shared secret, and then generate a confirmation message authentication code for comparison with the message authentication code decrypted from the received message.

[0037] System 200 provides a basis for authenticating messages using a shared secret without requiring an entity tasked with provisioning a sending system to transmit the shared secret in clear text to a potential receiving system. As discussed above, this approach may be of particular value in the area of ​​card-based transactions, where the sending / transmission processing system may be a card-mounted microprocessor and the receiving processing system may be a receiving / authentication gateway for a card transaction processing system.

[0038] 3-8 , transaction card communication system 300 includes a transaction card 320 associated with a user account. Transaction card 320 may be one of multiple cards distributed by a card issuer for use in conducting financial transactions via one or more transaction processing entities. System 300 includes a card issuer processing system 350 managed by the card issuer and one or more card message processing systems 360 managed by the one or more transaction processing entities. System 300 may also include one or more user devices 310, each associated with a user, which may be associated with a user account. System 300 may also include one or more transaction processing machines 340 configured to facilitate financial transactions involving transaction card 320. Each of user device 310, transaction processing machine 340, card issuer processing system 350, and card message processing system 360 may be or include a network-enabled data processing system configured for selective communication over network 330.

[0039] Network 330 may be or may include a wireless network, a wired network, or any combination of wireless and wired networks, and may be configured to connect one or more transmitting systems (e.g., user device 310 and transaction processing machine 340) and one or more receiving systems (e.g., card message processing system 360) to various servers and systems (e.g., card issuer processing system 350). The network 330 may include, for example, one or more of an optical fiber network, a passive optical network, a cable network, an Internet network, a satellite network, a wireless LAN, a Global System for Mobile Communications (GSM), a Personal Communications Service (PCS), a Personal Area Network, a Wireless Application Protocol (WAP), a Multimedia Messaging Service (MMS), an Enhanced Messaging Service (EMS), a Short Message Service (SMS), a time division multiplexing (TDM) based system, a code division multiple access (CDMA) based system, D-AMPS, Wi-Fi, fixed wireless data, IEEE 802.11b, 802.15.1, 802.11n and 802.11g, Bluetooth, near field communication (NFC), radio frequency identification (RFID), Wi-Fi, and / or the like.

[0040] Additionally, network 330 may include a global network such as, but not limited to, telephone lines, optical fiber, IEEE Ethernet 902.3, a wide area network (WAN), a wireless personal area network, a local area network (LAN), or the Internet. Additionally, network 330 may support an Internet network, a wireless communication network, a cellular network, or the like, or any combination thereof. Network 330 may further include one network or any number of networks of the above exemplary types, operating as a standalone network or in cooperation with one another. Network 330 may utilize one or more protocols of one or more network elements to which they are communicatively coupled. Network 330 may translate one or more protocols of network devices to or from other protocols. While network 330 is shown as a single network, it should be understood that, according to one or more examples, network 330 may include multiple interconnected networks, such as the Internet, a service provider's network, a cable television network, an enterprise network such as a credit card association network, and a home network.

[0041] Transaction cards 320 used in embodiments of the present invention may include chip-carrying transaction cards ("smart" cards) with telecommunications and / or near-field communication or other short-range communication capabilities. As shown in FIGS. 3 and 4 , a typical transaction card 320 usable in various embodiments of the present invention is a smart card having a microprocessor chip 321. The microprocessor chip 321 includes processing circuitry for storing and processing information, including a microprocessor 322 and memory 326, and may also include a power management system 325. It will be understood that the processing circuitry may include additional components, including a processor, memory, error and parity / CRC checkers, data encoders, anti-collision algorithms, controllers, command decoders, security primitives, and tamper-proof hardware, as needed to perform the functions described herein.

[0042] The transaction card 320 is configured to communicate with transaction processing machines and other devices via a terminal communication interface 324. The interface 324 and the microprocessor 322 may be configured, among other things, to establish communication with a merchant transaction processing device 340 for conducting purchases and other transactions. The communication interface 324 may be configured to provide contact-based communication, in which case the interface 324 may have electrical circuitry and contact pads on the surface of the card 320 to establish direct electrical communication between the microprocessor 322 and the processing circuitry of the transaction terminal 340. Alternatively or additionally, the first communication interface 324 may be configured for contactless communication with the transaction terminal 340. In such an embodiment, the communication interface 324 may be or include an NFC communication interface configured to communicate with other NFC communication devices when the card 320 is within a predetermined NFC distance. The communication interface 324 and the microprocessor 322 may also be configured to establish NFC communication with the user device 310. In some embodiments, the microprocessor chip 321 may include a second communication interface 328 configured to establish short-range communications with the user device 310 via Bluetooth or other short-range communications methods. In such embodiments, the transaction card 320 may have a short-range communications antenna 329 included in or connected to the short-range communications interface 328.

[0043] In particular embodiments, transaction card 320 may be Bluetooth-enabled using microprocessor chip 321, second communication interface 328, and antenna 329. Bluetooth-enabled transaction cards may support Bluetooth Low Energy (BLE) and may be paired with user device 310. In some embodiments, pairing and communication may be established between transaction card 320 and other interfacing devices such as a terminal (not shown), merchant transaction processor 340, etc. Bluetooth-enabled devices may include the ability to establish a link between the card and the device (or pair the device) using a mobile application(s) associated with the card issuer that may cooperate with device settings (e.g., iOS or Android settings that manage Bluetooth connections) and / or device controls to manage the Bluetooth connection with card 320.

[0044] Memory 326 may be read-only memory, write-once-read multiple memory, or read / write memory, such as RAM, ROM, and EEPROM, and chip 321 may include one or more of these memories. Memory 326 may store information associated with a transaction card account. In some embodiments, memory 326 may permanently store a unique alphanumeric identifier associated with the account. Memory may also have permanently stored public and private card encryption keys. In some embodiments, the private and public encryption keys may be permanently hardwired into the card memory.

[0045] The memory 326 may be configured to store one or more software applications for execution by the microprocessor 322. In particular embodiments, the card memory 326 stores a transaction processing application configured to conduct a financial transaction at the merchant terminal 340 or via the user device 310. The application includes instructions for the microprocessor 322 to establish communication with the transaction terminal 340 or the user device 310. In the case of a transaction terminal interaction, communication may be established when the transaction card 320 is introduced into the transaction terminal 340 by inserting the card 320 for electrical contact, by bringing the card 320 within NFC communication range of the transaction terminal 340, or by tapping the transaction card 320 against the transaction terminal 340. In the case of a user device interaction, communication may be established by bringing the card 320 within NFC communication range of the user device 310 or by tapping the transaction card 320 against the user device 310. The application instructions may be configured to cause the microprocessor 322 to receive information regarding the financial transaction from the transaction terminal 340 via the first communication interface 324. Such transaction information may include the type of transaction (e.g., purchase, refund, transfer, account charge, etc.) and monetary value. Transaction information may also include information about the terminal 340 and / or the entity managing the terminal 340. Such information may include, for example, a terminal or merchant identifier and / or location information.

[0046] In various embodiments, memory 326 may store instructions for generating an encrypted communication for transmission to a remote card message processing system 360 via an intermediate network-enabled device, such as a user device 310 or a transaction processing machine 340. In particular examples, these instructions may be configured to construct a transaction message having encrypted and unencrypted portions and including a message authentication code.

[0047] To prepare a transaction message, the application may be configured to utilize a card-unique key (referred to herein as a unique derivative key, or UDK) and an appropriate symmetric encryption algorithm to establish a secret session key for encryption of the sensitive message content. In some embodiments, the UDK may be stored in memory 326 and retrieved for use therefrom. In other embodiments, the UDK may be generated on demand using a UDK master key retrieved from memory 326 and a card identifier retrieved from memory 326. In some embodiments, additional parameters may be used in the construction of the shared symmetric session key. One example is a counter that is updated each time an encrypted communication for card message processing system 360 is encrypted and transmitted. In some embodiments, the counter or other parameter may be included in the encrypted transmission and / or in an unencrypted attachment to the encrypted transmission.

[0048] The symmetric algorithm used may include any symmetric encryption algorithm capable of generating diversified symmetric keys of the desired length. Non-limiting examples of symmetric algorithms may include symmetric encryption algorithms such as 3DES or AES128, symmetric HMAC algorithms such as HMAC-SHA-256, and symmetric CMAC algorithms such as AES-CMAC. It will be appreciated that if the output of the selected symmetric algorithm does not produce a sufficiently long key, techniques such as processing multiple iterations of the symmetric algorithm with different input data and the same master key can produce multiple outputs that can be combined as necessary to generate a key of sufficient length.

[0049] The encryption application may be configured to process some or all of the set of information for transmission to card message processing system 360 using the constructed symmetric encryption session key. For example, microprocessor 322 may encrypt a sensitive portion of data using a symmetric encryption algorithm and the session key, with the output including the encrypted set of information. The microprocessor may then transmit a message including the encrypted set of information via terminal communication interface 324 or short-range communication interface 328, which is relayed over network 330 to card message processing system 360. The message may also include unencrypted information, which may include, for example, a card identifier and / or information about the transaction. In certain embodiments, additional communication parameters (e.g., a counter) may be included.

[0050] In certain embodiments, the transaction message may include a message authentication code generated using a shared secret value. In some embodiments, the card 320 may be provisioned with an assigned shared secret value, which may be stored in memory 326 at the time of card issuance. The cryptographic application may be configured to retrieve the stored shared secret value from memory 326 when constructing a message for transmission to the card message processing system 360. The shared secret value may then be used as a salt value in any known cryptographic algorithm to generate the message authentication code. In some examples, one or more other shared or determinable communication parameters (e.g., an encrypted communication counter) may be used along with the shared secret value to generate the message authentication code.

[0051] In some embodiments, the transaction card 320 is not provided with a static shared secret value, but instead is provided with a shared secret master key that can be used to dynamically generate a shared secret value when needed. The shared secret master key may be stored in memory 326 upon provisioning of the transaction card 320. An encryption application may be configured to retrieve the shared secret master key and combine it with a card identifier or other fixed card parameters in an encryption algorithm to generate a shared secret value. The resulting shared secret value may then be used to construct a message authentication code. In some examples, one or more other shared or determinable communication parameters (e.g., an encrypted communication counter) may be used along with the shared secret master key and the card identifier to generate the shared secret.

[0052] In some examples, the message authentication code may be included in the secret data portion encrypted using the session key discussed above. However, in some embodiments, the message authentication code may be encrypted separately to generate a card authentication code ciphertext that can be attached to the message. In some embodiments, this ciphertext may be generated using the same session key used to encrypt the secret portion of the message. However, in other embodiments, the message authentication code may be encrypted using a second shared session key generated using a second UDK. The second UDK may be stored in memory 326 upon provisioning of the card 320, or the second UDK may be dynamically generated on demand from a second UDK master key stored in card memory 326. In either case, the second UDK may be combined with the card identifier to generate a second session key, which can be used to encrypt the message authentication code to generate the message authentication code ciphertext. The ciphertext may then be attached to the transaction message, which may then be transmitted to card message processing system 360.

[0053] Referring to FIG. 5, the account holder or user device 310 may be any network-enabled data processing and / or communication device used by the account holder to receive notifications from a transaction processor and / or to conduct transactions, including, but not limited to, smartphones, laptops, desktop computers, and tablets. In certain embodiments, the account holder device 310 includes an on-board data processor 311 in communication with a memory module 313, a user interface 314, and a network communication interface 312. In some embodiments, the account holder device 310 may include an image capture device (e.g., a digital camera). The data processor 311 may include a microprocessor and associated processing circuitry and may include additional components, including a processor, memory, error and parity / CRC checkers, data encoders, anti-collision algorithms, controllers, command decoders, security primitives, and tamper-proof hardware, as needed to perform the functions described herein. The memory 313 may be read-only memory, write-once-read multiplexed memory, or read / write memory, such as RAM, ROM, and EEPROM, and the user device 310 may include one or more of these memories.

[0054] The user interface 314 includes a user input mechanism, which can be any device for entering information and commands into the account holder device 310, such as a touch screen, keyboard, mouse, cursor control device, microphone, stylus, or digital camera. The user interface 314 may also include a display, which can be any type of device for presenting visual information, such as a computer monitor, flat panel display, and mobile device screen, including liquid crystal displays, light emitting diode displays, plasma panels, and cathode ray tube displays.

[0055] The network communication interface 312 may be configured to establish and support wired or wireless data communication capabilities for connecting the device 310 to the network 330 or other communication networks. The user device 310 may also have a near field communication (NFC) communication interface 319 that may be configured to support short-range wireless communication such as NFC, radio frequency identification, and Bluetooth. The NFC interface 319 may be configured, among other things, to establish near field wireless communication with a data processing chip 321 mounted on a transaction card 320 and to receive information transmitted by the data processing chip 321 via the chip NFC interface 324.

[0056] In embodiments of the invention, memory 313 may store one or more applications usable by data processor 311 to conduct and / or monitor transactions between user device 310, transaction processing machine 340, and other transaction processing systems. These applications may include instructions usable by data processor 311 to identify transaction events, store event data in memory 313, and communicate the event data. In some embodiments, the applications may include instructions for receiving transaction messages from transaction cards 320 and transmitting such messages over network 330 to card message processing system 360. The applications may be configured to instruct data processor 311 to interpret some or all of the unencrypted portions of the messages.

[0057] 6, transaction processing machine (TPM) 340 may be any network-enabled processor configured to process transactions involving transaction card 320. TPM 340 may be, for example, a cash register, an automated teller machine, a vending machine, or other point-of-sale terminal capable of communicating with transaction card 320 and with card message processing system 360 over network 130. In some embodiments, TPM 340 may include a TPM data processor 341, a network communication interface 342, a TPM user interface 344, memory 343, and a card communication interface 346.

[0058] The TPM data processor 341 may include a microprocessor and associated processing circuitry, and may include additional components including processors, memory, error and parity / CRC checkers, data encoders, anti-collision algorithms, controllers, command decoders, security primitives, and tamper-proof hardware as needed to perform the functions described herein. The memory 343 may be read-only memory, write-once-read multiple memory, or read / write memory, such as RAM, ROM, and EEPROM, and the transaction processing machine 340 may include one or more of these memories.

[0059] TPM user interface 344 may include a user input mechanism, which may be any device for entering information and commands into TPM 340, such as a touch screen, keyboard, mouse, cursor control device, microphone, stylus, or digital camera. User interface 344 may also include a display, which may be any type of device for presenting visual information, such as a computer monitor, flat panel display, and mobile device screen, including liquid crystal displays, light emitting diode displays, plasma panels, and cathode ray tube displays.

[0060] Network communication interface 342 can be configured to establish and support wired or wireless data communication capabilities for connecting machine 340 to network 330 or other communication networks. Card communication interface 346 can be configured to accept transaction card 320 and make electrical contact for wired communication between TPM data processor 341 and transaction card processor 321. Alternatively or additionally, card communication interface 346 may be configured to support short-range wireless communication between transaction card 320 and TPM data processor, such as near field communication (NFC), radio frequency identification, and Bluetooth. Card communication interface 346 can be configured, among other things, to establish wired or wireless communication with data processing chip 321 on board transaction card 320 and to receive information transmitted by data processing chip 321 via chip terminal communication interface 324.

[0061] In embodiments of the invention, TPM memory 343 may store one or more applications usable by data processor 341 to perform transactions and communicate with a transaction processing system. These applications may include instructions usable by data processor 341 to identify transaction events, store event data in memory 343, and communicate the event data. In some embodiments, the applications may include instructions for receiving transaction messages from transaction cards 320 and transmitting such messages over network 330 to card message processing system 360. The applications may be configured to instruct data processor 341 to interpret some or all of the unencrypted portions of the messages.

[0062] A card issuer processing (CIP) system 350 may be associated with a transaction card issuing institution that may provide and distribute a large number of transaction cards 320, with each such card 320 associated with one or more user accounts. The card issuing institution may be the administrator of such user accounts, or may be directly associated with the administrator of such user accounts, or may be a separate contracting entity. In either case, the card issuing institution may utilize the card issuer processing system 350 to provision the transaction cards 320 with applications and data for conducting secure communications according to embodiments of the present invention.

[0063] 7, CIP system 350 is a network-enabled automated data processing system that may include a card assignment processor 353, an encryption key generation processor 354, a shared secret generation processor 355, and a key distribution processor 356. CIP system 350 may also include a card communication interface 352 configured for wired or wireless communication with transaction card 320 and a network communication interface 351 configured to establish communications with network 330 and / or other networks. In some embodiments, CIP system 350 may include a card database 359. In other embodiments, card database 359 may be separate from CIP system 350 but accessible by the CIP system.

[0064] The card communication interface 352 is configured to allow one or more of the provisioning processors 353, 354, and 355 to pass information directly to the memory 326 of the transaction card 320. This may be achieved by direct electrical / data communication via electrical contacts on the card chip 321. Alternatively or additionally, the card communication interface 352 may be configured for contactless communication with the card chip 321 via the card's terminal communication interface 324 or short-range communication interface 328. In such embodiments, the card communication interface 352 may be or include an NFC communication interface configured to communicate when the card 320 is within a predetermined NFC distance. The card communication interface 352 may also be configured to establish short-range communication via Bluetooth or other short-range communication methods.

[0065] The CIP system 350 may include one or more automated data processors configured to provision the microprocessor chips 321 of the multiple transaction cards 320. In some embodiments, this may include a card assignment processor 353 configured to establish wired or wireless communication with the chips 321 of the cards 320 via a card communication interface 352. The card assignment processor may be further configured to generate or otherwise determine one or more card identifiers for the cards 320 and transmit for storage or otherwise permanently store the one or more card identifiers in the memory 326 of the cards 320. The card assignment processor 353 may also store the one or more identifiers in a record in a card database 359.

[0066] The one or more automated data processors of the CIP system 350 may also include an encryption key generation processor 354. This processor 354 may be configured to generate encryption keys usable by the card microprocessor 322 to encrypt message content. In certain embodiments, the encryption key generation processor 354 may be configured to generate one or more UDK master keys, each of which can be combined with one of the one or more card identifiers to generate a card-unique UDK. The UDK master keys may be generated using any secure random or pseudo-random number generator. Each UDK master key may be associated with or included in a card record stored in the card database 359. In some embodiments, each UDK master key may be associated with the unique identifiers of multiple transaction cards 320. In such embodiments, the UDK master keys may be stored separately and associated only with individual card records. In some embodiments, the encryption key generation processor 354 may transmit for storage or otherwise permanently store one or more UDK master keys in the memory 326 of the card 320. In such an embodiment, the card microprocessor 322 may use each UDK master key to generate a card-unique UDK, which can then be used to generate a communication session key for encryption. In other embodiments, the encryption key generation processor 354 may itself use the card-associated UDK master key in combination with the card identifier to generate a card-unique UDK, which is then transmitted for storage or otherwise permanently stored in the memory 326 of the card 320. In such an embodiment, the card microprocessor 322 does not need to regenerate the UDK for each communication; it simply needs to retrieve the UDK from the memory 326.

[0067] The one or more automated data processors of the CIP system 350 may also include a shared secret generation processor 355. The shared secret generation processor 355 may be configured to generate a shared secret master key that can be combined with one of the one or more card identifiers to generate a shared secret value for the card 320. The shared secret master key may be generated using any secure random or pseudo-random number generator. The shared secret master key may be associated with or included in a card record stored in the card database 359. In some embodiments, the shared secret master key may be associated with unique identifiers for multiple transaction cards 320. In such embodiments, the shared secret master keys may be stored separately and associated only with individual card records. In some embodiments, the shared secret generation processor 355 may transmit the shared secret master key for storage or otherwise permanently store it in the memory 326 of the card 320. In such embodiments, the card microprocessor 322 may use the shared secret master key in combination with one of the one or more card identifiers to generate a card-unique shared secret value that can be used to generate a message authentication code, as described above. In other embodiments, the shared secret generation processor 355 may itself generate the shared secret value using the shared secret master key in combination with the card identifier, which is then transmitted for storage or otherwise permanently stored in the memory 326 of the card 320. In such embodiments, the card microprocessor 322 does not need to regenerate the shared secret for each communication; it need only retrieve the shared secret from the memory 326. In all embodiments, the shared secret master key may be associated with or included in the card record for the card 320 stored in the card database 359.

[0068] CIP system 350 may also include a key distribution processor 356 configured to communicate with one or more card message processing systems 360 via network communication interface 351 and network 330. Key distribution processor 356 may be configured to retrieve card information from the card record for each card 320 and transmit it to some or all of the card message processing systems 360. Such card information may include one or more unique card identifiers, one or more UDK master keys associated with the card 320, and a shared secret master key. In embodiments in which a master key is associated with multiple card identifiers, the master key may not be included in each card record. In such embodiments, the master key may be transmitted separately from the card record. In particular embodiments, key distribution processor 356 may be configured to transmit a single instance of each master key along with the identifiers of all cards 320 associated with these master keys. Key distribution processor 356 may also be configured to identify or provide copies of the algorithms used to generate the UDKs and shared secrets from their respective master keys. In some embodiments, the transmission of card information may occur in response to a card information request from card message processing system 360. The key distribution processor 356 may be configured to receive, evaluate, and verify such requests and transmit card information only upon verifying the card message processing system 360's authorization to receive such information for a particular card (or cards) 320.

[0069] A card message processing (CMP) system 360 may be associated with a transaction processor, a card transaction administrator, or other entity authorized to receive communications transmitted by a transaction card 320 via an intermediate device (e.g., a user device 310 or a transaction processing machine 340). Referring to FIG. 8 , the CMP system 360 may include a network communication interface 361 configured to selectively communicate over the network 330 and / or other networks. A card record management system 362 may be configured to receive card information for one or more transaction cards 320 from the CIP system 350 and store such information in a card database 369. Each card record in the database 369 may include, without limitation, one or more unique card identifiers, one or more UDK master keys, and a shared secret master key. In some embodiments, each card record may also include an encrypted communication counter. In some embodiments, rather than the actual UDK and shared secret master key, the card record may include a master key index reference, enabling retrieval of a master key associated with a particular card from a separate storage medium (e.g., in another encrypted information database or in a secure module of the CMP system 360). In embodiments in which UDKs and shared secret master keys are associated with card identifiers for multiple transaction cards 320, the card record may include only an indication of the association of such master keys with one or more unique card identifiers. In particular embodiments, the stored master keys may include a first UDK master key for use in generating UDKs for decrypting message content and a second UDK master key for use in generating UDKs for decrypting message authentication code ciphertext.

[0070] The CMP system 360 may also include one or more automated data processors configured to receive and decode messages received from the transaction cards 320. These one or more communication interpretation processors may include a transaction message reception data processor 363 configured to receive and evaluate each message. This may include, for example, interpreting unencrypted information, which may include identifying information (e.g., a unique card identifier) ​​sufficient to identify the particular card 320 from which the communication was received. In some embodiments, the unencrypted information may include an encrypted communication counter value, or information from which such a counter may be derived.

[0071] The one or more communication interpretation processors of the CMP system 360 may also include a decryption processor 364 configured to decrypt at least a portion of the decrypted information in the received message. This may include retrieving a first UDK master key for the card 320 from a card database 369 (or other storage location) and generating a first UDK using the first UDK master key in combination with an appropriate card identifier. The first UDK can then be used to create a first session key for decrypting at least a portion of the encrypted content of the received message. The decrypted information may be or include confidential transaction information that may be stored and / or forwarded to the transaction processing system 366. In some embodiments, the decryption processor 364 may be configured to update an encrypted message counter associated with the transaction card 320. This counter may then be compared to the counter value received in the message and / or used as a shared parameter in either a key or shared secret generation algorithm.

[0072] As previously mentioned, the portion of the message containing sensitive information encrypted with a particular session key may, in some embodiments, also include a message authentication code encrypted using the same session key. In such embodiments, the decryption processor 364 may forward the decrypted method authentication code to the authentication processor 365 for use in authenticating the message. However, in other embodiments, the method authentication code may be encrypted separately, and the resulting ciphertext is appended to the encrypted message. In such embodiments, the decryption processor 364 may be configured to retrieve the second UDK master key for the card 320 from the card database 369 (or other storage location) and generate a second UDK using the second UDK master key in combination with the appropriate card identifier. The second UDK may then be used to create a second session key for decrypting the method authentication code ciphertext. The decrypted method authentication code may then be forwarded to the authentication processor 365.

[0073] The authentication processor 365 may be configured to authenticate the received message based on a comparison of the decrypted parameters with unencrypted information received in the message and / or information stored in the card record of the card 320. In particular embodiments, the authentication processor 365 may be configured to generate a method authentication code from the known parameters of the card 320 and compare it with the method authentication code decrypted from the received message. In doing so, the authentication processor 365 may retrieve a shared secret master key from storage and use it, along with an appropriate card identifier and an appropriate diversification algorithm, to generate the shared secret. In certain embodiments, the shared secret generation may also require one or more additional shared parameters (e.g., an encrypted message counter). In such embodiments, the authentication processor 365 may also be configured to retrieve or otherwise determine the required one or more additional shared parameters for use in generating the shared secret.

[0074] The authentication processor 365 may be further configured to generate a method authentication code using the generated shared secret and an appropriate algorithm and compare it to the decrypted method authentication code from the message. A match indicates the authenticity of the message and its source. If the codes do not match, the authentication processor 365 may transmit an error message to the transaction processing system 366 and / or to an intermediate device to which the transaction card 320 transmitted the message (e.g., the user device 310 or the transaction processing machine 340). The authentication processor 365 may also terminate further processing of the message and any associated transaction. The authentication processor may also decrement an encrypted message counter.

[0075] The authentication processor may be configured to pass the authentication result to the transaction processing system 366. In some embodiments, the transaction processing system 366 may be configured to process information from the received message to initiate or complete a transaction. In other embodiments, the transaction processing system 366 may be configured to construct a transaction processing request and transmit it to a transaction processing institution or other financial entity for processing.

[0076] 9 generally illustrates a series of operations in an exemplary use of transaction card communication system 300. At 1100, a card issuer processing system generates keys and / or shared secrets for a particular transaction card as part of the provisioning process for that card. The generated keys include one or more UDK master keys and a shared secret master key. In embodiments where the shared secrets are statically stored in card memory, the card issuer may generate the shared secrets from the shared secret master key and the card identifier. At 1200, the card issuer processing system provisions the card with the transaction card identifier and one or more UDK master keys. The card issuer processing system also provisions the card with either the shared secret master key or the shared secret itself.

[0077] At 1300, the card issuer processing system transmits card information to the card message processing system. This information may include a card identifier, one or more UDK master keys, and a shared secret master key. In embodiments where master keys are each usable with card identifiers of multiple cards, the card issuer may transmit a single instance of each master key along with the identifiers of all cards associated with those master keys. At 1400, the card message processing system stores some or all of the card record in a card database for future use in interpreting messages from the transaction card.

[0078] At some point after provisioning, the card is issued to the account holder for use. At 1500, as part of the transaction encounter, the transaction card microprocessor constructs a message for transmission to the card message processing system. In doing so, the card microprocessor may retrieve a shared secret from card memory or may retrieve a shared secret master key and use it to generate a shared secret as described above. The shared secret may then be used to generate a message authentication code. The card microprocessor may then retrieve a first UDK master key and use it to generate a first UDK, which may further be used to generate a session key for encrypting at least a portion of the message. In some embodiments, the card microprocessor may also retrieve a second UDK master key for use in generating a second UDK for encrypting the message authentication code.

[0079] At 1600, the transaction card transmits a message to an intermediate device with which the card is interacting to conduct the transaction for retransmission to the card message processing system. Depending on the situation, the intermediate device may be, for example, an account holder's mobile device or a merchant's transaction processing machine. The message may be transmitted via direct electrical contact or via NFC or other short-range communication modes. At 1700, the intermediate device transmits the message to the card message processing system.

[0080] At 1800, the card message processing system receives and processes the message. This may include identifying the card based on the unencrypted content of the message and, based on this identification, retrieving decryption information for the card from a card database. In particular, the card message processing system may retrieve the first UDK master key and (if appropriate) the second UDK master key and use them to generate the keys necessary to decrypt the encrypted content and method authentication code. The card message processing system then decrypts the message and message authentication code. The shared secret master key is then retrieved and used to generate a shared secret, which is then used to generate a message authentication code value for comparison with the code obtained from the message to authenticate the message and its source.

[0081] Referring now to FIG. 10 , a method M100 for facilitating encrypted message authentication will be described. Method M100 may be performed by a network-enabled key generation and control system, such as system 240 shown in FIG. 2 or card issuer processing system 350 of FIG. 3 . At S110 of method M100, the key generation and control system may generate one or more encryption master keys for use in generating encryption and session keys for encryption of messages by a sending data processing system to be sent to a receiving data processing system. These master keys may be, for example, the UDK master keys used by transaction card 320 of FIGS. 3 and 4 . At S120, the key generation and control system may generate a shared secret master key for use in generating a shared secret value usable to generate a message authentication code. In some embodiments, the system may optionally generate the actual shared secret using the shared secret master key and a predetermined shared secret generation algorithm. In certain embodiments, the shared secret generation algorithm may require the use of an identifier or other unique information associated with the sending processing system. The key generation and control system may use an existing identifier or establish an identifier for the sending processing system. In embodiments where the sending data processing system is a microchip on a transaction card, the identifier may be the card number or other card unique identifier. At S140, the key generation and control system may associate the encryption master key(s) and the shared secret master key with the identifier of the sending system and store the keys and identifier in an encryption key database.

[0082] At S150, the key generation and control system provides the first communication system (i.e., the transmitting data processing system) with one or more encryption master keys and either the shared secret master key or the shared secret itself. A particular key generation and / or encryption algorithm may also be identified or provided. In embodiments where the first communication system is a transaction card, the master key, algorithm, and / or shared secret may be stored directly in card memory or transmitted to the card microprocessor as part of the card provisioning process. In other embodiments, the master key and algorithm identification (or algorithms) may be transmitted over a network to the first communication data processing system. In embodiments where encryption information is transmitted over a network, the shared secret itself is preferably not transmitted.

[0083] At S150, the key generation and control system transmits one or more encryption master keys, key generation and encryption algorithms, and the shared secret master key to a second communication system (ie, a receiving data processing system) over a network.

[0084] Referring to FIG. 11, a method M200 for constructing an encrypted communication is described. Method M200 may be performed by a network-enabled processing system configured to function as a sending system of a symmetric communication pair. Such a sending system may be, for example, sending system 110 of FIG. 1, sending system 210 of FIG. 2, or transaction card microprocessor 322 of FIG. 4. At S210 of method M200, the sending system assembles message content, which may include a first portion consisting of non-sensitive information and a second portion consisting of sensitive information. The non-sensitive information may be or include, for example, information usable by a receiving system to identify the sending system and / or other non-sensitive parameters (e.g., a message counter). In some embodiments, the operation of assembling the message content may be initiated in response to an authentication request received by the sending system. At S220, the sending system establishes a shared secret value usable to generate a message authentication code. In embodiments in which the shared secret is statically stored in memory accessible by the sending system's data processor, the data processor may establish the shared secret value by retrieving the shared secret from memory. In other embodiments, the data processor may retrieve a shared secret master key from memory and use it in combination with the sending system's unique identifier in a shared secret generation algorithm to generate a shared secret. In some embodiments, the shared secret algorithm may also require another shared parameter (e.g., an encrypted message counter) to generate the shared secret value. At S230, the shared secret value may be used by the sending system data processor as a salt in a MAC generation algorithm to generate a message authentication code.

[0085] At S250, the sending data processing system encrypts at least a portion of the message content. In particular embodiments, the sensitive information portion may be encrypted using a first session key. In some embodiments, the message authentication code may be encrypted together with the sensitive information portion using the first session key. In other embodiments, the message authentication code may be separately encrypted using a second session key to generate a message authentication ciphertext. As part of the encryption operation, the sending system may retrieve a first encryption master key from memory and combine it with a sending system-unique identifier in an encryption key generation algorithm to generate a first sending system-unique encryption key (e.g., the first UDK described above in connection with system 300 of FIG. 3), which may then be used to generate a first session key. Similarly, the sending system may retrieve a second encryption master key from memory and combine it with a sending system-unique identifier to generate a second sending system-unique encryption key (e.g., the second UDK described above in connection with system 300 of FIG. 3), which may be used to generate a second session key. In some embodiments, the encryption key generation algorithm may also require another shared parameter (e.g., an encrypted message counter) to generate the shared secret value. In embodiments in which an encrypted message counter is used, the counter may be incremented upon encryption of the message or upon transmission of the encrypted message.

[0086] At S260, the sending system assembles the unencrypted and encrypted portions of the message and transmits it over the network to the receiving communication system. In some embodiments, the sending system may transmit the assembled message to the receiving communication system via an intermediate communication device, receive the message, and retransmit it over the network to the receiving communication data processing system.

[0087] Referring to FIG. 12, a method M300 for authenticating encrypted communications is described. Method M300 may be performed by a network-enabled processing system configured to function as a receiving system of a symmetric communication pair. Such a receiving system may be, for example, receiving system 120 of FIG. 1, receiving system 220 of FIG. 2, or card message processing system 360 of FIGS. 3 and 8. The receiving system stores or has access to a database containing encryption information for one or more sending data processing systems. This encryption information may include one or more sending system-specific identifiers, one or more encryption master keys, and a shared secret master key. In some embodiments, each master key may be associated with identifiers for more than one sending system but is usable with the sending system-specific identifiers to generate a sending system-specific encryption key. In some embodiments (e.g., system 200 of FIG. 2 and system 300 of FIG. 3), the encryption information may be received from a third-party data processing system that generates and distributes the master keys.

[0088] At S310, a receiving data processing system receives a message containing encrypted information from a sending system, transmitted over a network. In certain embodiments, the message may be received from an intermediate device (e.g., user device 310 of FIG. 3 or a transaction processing machine), which receives the message from the sending device and retransmits it over the network to the receiving system. At S320, the receiving system reviews the message and processes / reads the unencrypted portion of the message. At S330, the receiving system determines an identifier for the sending data processing system. In some embodiments, this may be contained in or determinable from the unencrypted information in the message.

[0089] At S340, the receiving data processing system decrypts the encrypted portion of the message. In some embodiments, the message includes a message authentication code and a sensitive content portion that are jointly encrypted using a first session key. As part of the operation at S340, the receiving system may generate or retrieve the first session key and use it to decrypt both the message authentication code and the sensitive content. In embodiments in which a first session key is generated, the receiving system may retrieve the first encryption master key from an encryption information database and combine it with the sending system identifier in an appropriate encryption key generation algorithm to generate a first sending system-unique encryption key (e.g., the first UDK described above in connection with system 300 of FIG. 3 ), which may then be used to generate the first session key.

[0090] In some embodiments, the message authentication code is provided in a separately encrypted ciphertext constructed using a second session key. In these embodiments, the receiving system may retrieve the second encryption master key from an encryption information database and combine it with the sending system identifier to generate a second sending system-unique encryption key (e.g., the second UDK described above in connection with system 300 of FIG. 3) that can be used to generate a second session key, which can then be used to decrypt the message authentication code.

[0091] In some embodiments, the encryption key generation algorithm may also require another shared parameter (e.g., an encrypted message counter) to generate the shared secret value. In embodiments in which an encrypted message counter is used, the counter may be incremented upon receipt of an encrypted message or upon decryption of a message.

[0092] At S350, the receiving data processing system retrieves the shared secret master key from the encryption information database and uses it, along with the sending system identifier, to generate a shared secret value using an appropriate shared secret generation algorithm. In some embodiments, the shared secret generation algorithm may also require one or more additional shared parameters (e.g., an encrypted message counter) to generate the shared secret. At S360, the shared secret may be used in an appropriate MAC generation algorithm to generate a second message authentication code. At S370, the second message authentication code may be compared to the code decrypted from the message to authenticate the message. A match indicates the authenticity of the message and its source. In response to a positive determination of authenticity, the receiving system may further process information from the received message (e.g., to initiate or complete a transaction). However, if the authentication codes do not match, the receiving system may transmit an error message to the sending system and / or intermediate devices (if any) to which the sending system transmitted the message. The receiving system may also terminate further processing of the message content and any associated transactions. The receiving system may also decrement the encrypted message counter (if used).

[0093] The present invention provides a method and system for authenticating symmetrically encrypted communications in which a message authentication code can be generated based on a shared secret salt value that can be dynamically generated in parallel from a master key generated by a third-party system, resulting in more secure communication and construction of shared data required for symmetrically encrypted communications.

[0094] Those skilled in the art will readily appreciate that the present invention is susceptible to a wide range of utility and applications. Many embodiments and adaptations of the invention other than those described herein, as well as many variations, modifications and equivalent arrangements, will be apparent from, or reasonably suggested by, the invention and the foregoing description thereof, without departing from the spirit or scope of the invention.

Claims

1. A card, A data processor; a communication interface configured for contact or contactless communication with an intermediate processing device; Card memory and Equipped with The card memory includes: a shared secret master key and a unique card identifier; A message encryption application, comprising: generating a shared secret value using the unique card identifier and the shared secret master key; generating a message authentication code using the shared secret value; encrypting at least a portion of the message content using the first session key to generate encrypted message content; encrypting the message authentication code; transmitting a message including the encrypted message content and the encrypted message authentication code to the intermediate processing device for retransmission to a receiving communication processing system; a message encryption application including instructions for: Memorize the card.

2. The card of claim 1 , wherein the message authentication code is encrypted using the first session key.

3. The card memory also stores at least one encryption master key; The message encryption application may further comprise: generating a first card-unique encryption key using the unique card identifier and a first encryption master key of the at least one encryption master key; generating the first session key using the first card-unique encryption key; The card of claim 1 further comprising instructions for:

4. The message encryption application may further comprise: generating a second card-unique encryption key using the unique card identifier and a second encryption master key of the at least one encryption master key; generating a second session key using the second card-unique encryption key; further comprising instructions for: the message authentication code is encrypted using the second session key; 4. The card of claim 3.

5. The card memory also stores an encryption counter; the message encryption application uses the encryption counter together with the unique card identifier and the shared secret master key to generate the shared secret value; the message encryption application further comprising instructions for the data processor to increment the encryption counter after generating the message authentication code. The card of claim 1.

6. The card of claim 5 , wherein the encrypted counter is included in the message.

7. 1. A method for facilitating symmetrically encrypted communications between a transmitting data processing system and a receiving data processing system having associated unique identifiers, the method comprising: generating, by a key generating data processing system, at least one encryption master key, each encryption master key configured for use with the unique identifier and a first encryption algorithm to generate a transmission system unique encryption key; generating, by the key generating data processing system, a shared secret master key configured for use with the unique identifier and a second encryption algorithm to generate a shared secret value; said key generation data processing system storing said at least one encryption master key and said shared secret master key in association with said unique identifier in an encryption information database; transmitting the at least one encrypted master key and shared secret information to the transmitting data processing system; said key generating data processing system transmitting said at least one encrypted master key, said shared secret master key, and said unique identifier to said receiving data processing system; A method comprising:

8. the key generation data processing system further comprising generating a shared secret value using the shared secret master key and the second encryption algorithm; the shared secret information is or includes the shared secret value; The method of claim 7.

9. The method of claim 7 , wherein the shared secret information is or includes the shared secret master key.

10. 8. The method of claim 7, wherein the transmission data processing system is or includes a microprocessor onboard a transaction card, and the operations of generating at least one encryption master key, generating a shared secret master key, storing the at least one encryption master key and the shared secret master key, and transmitting the at least one encryption master key and the shared secret information occur as part of a provisioning process for the transaction card.

11. 11. The method of claim 10, wherein the receiving data processing system is a card message processing system configured to decrypt and authenticate messages transmitted by the transaction card using the at least one encryption master key and the shared secret master key.

12. 8. The method of claim 7, wherein each encryption master key is configured for use with an encryption counter, together with the unique identifier and the first encryption algorithm, to generate a transmission system unique encryption key.

13. 8. The method of claim 7, wherein a shared secret master key is configured for use with the unique identifier and the second encryption algorithm, along with an encryption counter, to generate the shared secret value.

14. 1. A method of authenticating a message transmitted by a sending data processing system having an associated unique identifier, the transmitted message including encrypted content and an encrypted message authentication code, the method comprising: a receiving data processing system receiving the transmitted message; the receiving data processing system determining the unique identifier; retrieving, by the receiving data-processing system, from a database, an encryption information record for the sending data-processing system, the encryption information record including a shared secret master key; the receiving data processing system decrypting the encrypted message authentication code; said receiving data processing system generating a shared secret value using said unique identifier and said shared secret master key; said receiving data processing system generating a comparative message authentication code using said shared secret value; the receiving data-processing system comparing the comparison message authentication code to the decrypted message authentication code to determine a message authentication result; A method comprising:

15. The encryption information record includes at least one encryption master key, and the method includes: generating, by the receiving data processing system, a first sending system unique encryption key using the unique identifier and a first encryption master key of the at least one encryption master key; generating a first session key using the first sending system unique encryption key; decrypting at least a portion of the encrypted content using the first session key; 15. The method of claim 14, further comprising:

16. 16. The method of claim 15, wherein the act of decrypting the encrypted message authentication code is performed using the first session key.

17. generating, by the receiving data processing system, a second sending system unique encryption key using the unique identifier and a second master key of the at least one master key; generating a second session key using the second sending system unique encryption key; further comprising decrypting the encrypted message authentication code using the second session key; 16. The method of claim 15.

18. The method of claim 14 , wherein the encryption information record further includes an encryption counter.

19. the receiving data processing system incrementing the encryption counter in the encryption information record; storing the encryption information record having the incremented encryption counter in the database; 20. The method of claim 18, further comprising:

20. the unencrypted portion of the transmitted message includes an encryption counter; generating a shared secret value using the unique identifier and the shared secret master key as well as the cryptographic counter; 15. The method of claim 14.

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