Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
  • H04L9/12—Transmitting and receiving encryption devices synchronised or initially set up in a particular manner
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
  • H04L9/32—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols including means for verifying the identity or authority of a user of the system or for message authentication, e.g. authorization, entity authentication, data integrity or data verification, non-repudiation, key authentication or verification of credentials
  • H04L9/3247—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols including means for verifying the identity or authority of a user of the system or for message authentication, e.g. authorization, entity authentication, data integrity or data verification, non-repudiation, key authentication or verification of credentials involving digital signatures

Definitions

• the present invention relates to a system for exchanging data between at least one "sending" computer system or terminal and at least one "receiving" computer system or terminal, by means of an internet-type data transmission network.
• Transmitting systems may for example be different boxes of a point of sale, which must be able to communicate with a central server (the receiver), in particular for inventory management or the consolidation of sales made.
• a central server the receiver
• the different boxes can be connected to a central server via network operators, through telecommunications lines that can be either private or public.
• Private lines also called VPN (Virtual Private Network) are used to build an internal network of the company or Intranet.
• the intranet of the company has the advantage of being completely securable since all the access points are determined in advance and may include internal security devices defined by the company.
• Public lines can be used for relations with partner organizations via an Extranet type network. Access to these lines is through an ISP (Internet Service Provider) type public network operator.
• ISP Internet Service Provider
• the company's Extranet is also completely secure since each partner can be identified through a Certification Authority (CA), and the link between each partner and the company can be considered as private (equivalent to a VPN line), even if it is part of the public network.
• CA Certification Authority
• Public lines can also be used for random and on-demand relationships with all customers and prospects of the company, via the Internet.
• the internet does not have a specific security feature, although passwords and access technologies on a server can be used but without guaranteeing a two-way security between a client and a server. Indeed, any access point of the public network having knowledge of the password security devices can access the information exchanged.
• an Internet-type network does not guarantee that the data received by the receiver has remained in conformity with that initially transmitted by the corresponding transmitter because of the risk of unintentional corruption of the frames transmitted by such an IP-based network ( Internet Protocol).
• the invention aims in particular to respond in a simple, effective and economical way to these needs, allowing the use of a public network type Internet in a completely secure and interactive way.
• the transmitter and the receiver each comprise first message encryption / decryption means, said first encryption / decryption means being designed to generate, from data comprising at least one variable data and secret codes specific to the sender and the receiver, variable encryption / decryption keys which change for each new sending of a message from the sender to the receiver, the encryption and the decryption of the messages being realized without transmission of these keys or data relating to these keys between the transmitter and the receiver.
• the encryption / decryption keys are permanently modified and are used without these keys and their obtaining data being exchanged or transmitted between the transmitter and the receiver, so that an intruder, even if it has encryption / decryption means identical to those of the transmitter and the receiver, can not decrypt the transmitted messages.
• the first means of encryption / decryption of the transmitter and the receiver comprise pseudo-random key generators which are identical and synchronized.
• Key generators typically comprise one-way hash functions, which generate encryption / decryption keys from fixed and variable input data, the fixed data advantageously including, in addition to the secret codes of the transmitter and the receiver , other fixed data such as, for example, symbolic codes specific to the transmitter and the receiver, the fixed data being preferably mixed, for example by concatenation, to further increase security.
• variable data in particular a synchronization datum set to an initial state before any exchange and systematically variable thereafter at each exchange, such that an operation number initially zero and incremented thereafter for each exchange made, and which may possibly be associated for example with a discounted date after each of said exchanges (a date also being a variable datum but which by nature is not systematically different each exchange), allows on the one hand to generate keys that will be different each time and on the other hand to synchronize the key generators of the transmitter and the receiver to make them generate associated keys encryption / decryption of new messages, without any exchange or transmission of data relating to these keys between the sender and the receiver.
• the system according to the invention also comprises means for resetting the synchronization data, such as, for example, means for resetting an operation number, to ensure resynchronization of the key generators after an interruption of the transceiver link, this interruption can occur unintentionally, for example in case of line break.
• the transmitter comprises means for signing each message sent to the receiver, for the authentication of the transmitter on receipt of a message by the receiver.
• the signature means advantageously comprise a signature key generator, such as a pseudo-random generator of the aforementioned type, which can generate variable signature keys for each operation, for example from the same fixed and variable data as the generators. encryption / decryption keys.
• a signature key generator such as a pseudo-random generator of the aforementioned type, which can generate variable signature keys for each operation, for example from the same fixed and variable data as the generators. encryption / decryption keys.
• the encryption of a message is performed after signature of this message.
• the receiver comprises means for authenticating the sender of a received and decrypted message, these means comprising a key generator identical to the signature key generator and generating keys from the aforementioned fixed and variable data. .
• the signature key generators and authentication means can thus be synchronized by incrementing a synchronization data identical to that of the transmitter, such as the operation number, with a reset of said synchronization data both on the receiver and on the transmitter, in case of interruption of the link transmitter receiver.
• the receiver comprises means for generating, after reception and decryption of a message sent by the transmitter, an encrypted acknowledgment message sent to the transmitter.
• Acknowledgment allows the sender to ensure that the message has reached the receiver, before sending a new message for example.
• the means for generating an acknowledgment message comprise means for encrypting an acknowledgment code, which is, for example, the date of the last acknowledgment performed by the receiver, by means of a key produced by a user. key generator from the above fixed data.
• the transmitter comprises means for decrypting the acknowledgment message sent by the receiver, by means of a decryption key produced by a key generator identical to that of the receiver from the aforementioned fixed data.
• the acknowledgment code decrypted by the transmitter can then be used as new variable data associated with the synchronization data, for the generation of the signature and encryption keys of the next message to be sent to the receiver.
• the data exchange system comprises means for checking the integrity and non-repudiation of each message transmitted, by adding to each message, before encryption, on the one hand the number characters (length) contained in the message, and on the other hand, a fingerprint obtained by hashing the set (message and length), then by checking the means of the imprint and then the length of the message after decryption.
• the hash is for example realized by means of an algorithm of the SHA type.
• the ciphers are made using an algorithm of the type AES (Advanced Encryption Standard) or DES (Data Encryption Standard), which are block cipher algorithms.
• AES Advanced Encryption Standard
• DES Data Encryption Standard
• the invention also relates to a method of exchanging encrypted data between a transmitter and a receiver, this method consisting in encrypting in the transmitter messages to be transmitted, the messages encrypted to the receiver by a network of the Internet type, to be decrypted in the receiving the received messages, and returning to the transmitter an acknowledgment message, characterized in that the messages are encrypted by means of a symmetric secret-key algorithm, it consists in generating in the transmitter and in the receiver encryption / decryption variable keys which are modified at each encryption / decryption and which are produced by identical and synchronized key generators installed in the transmitter and in the receiver, these keys being generated from fixed data including clean secret codes to the transmitter and the receiver and at least one synchronization datum that is systematically variable with each e exchange, such as an operation number, the encryption and decryption of messages being made without transmission of these keys or data relating to these keys between the sender and the receiver.
• this method also consists, in the transmitter, of signing each message before encryption, by using a signature key produced by a pseudo-random key generator and, in the receiver, to authenticate the transmitter using an authentication key produced by a pseudo-random key generator, the signature and authentication key generators being identical and synchronized.
• the method also consists in incrementally synchronizing a synchronization data that is systematically variable at each exchange, such as an operation number, the encryption / decryption and / or signature and authentication key generators, with a discount. in the initial state of said synchronization data in the event of a break in the link between the transmitter and the receiver.
• the acknowledgment message sent to the transmitter after reception and decryption of a message contains an acknowledgment code, for example the date of the last acknowledgment performed by the receiver, which is sent in encrypted form to the transmitter. and which is used in the receiver and after decryption in the transmitter, as new data associated with the synchronization data for generating a new variable key by the first encryption / decryption means.
• an acknowledgment code for example the date of the last acknowledgment performed by the receiver, which is sent in encrypted form to the transmitter. and which is used in the receiver and after decryption in the transmitter, as new data associated with the synchronization data for generating a new variable key by the first encryption / decryption means.
• FIG 1 shows schematically the essential means of the system according to the invention
• FIG. 2 is a flowchart of a start-up phase of the method according to the invention.
• FIG. 3 is a flowchart of the essential steps of the method according to the invention, for a specific application in which the transmitters are cash terminals of a point of sale.
• FIG. 1 diagrammatically shows the essential means of a data exchange system according to the invention, between boxes of a point of sale and a central server.
• Each box comprises means 1 for acquiring data, connected to information processing means 2 comprising microprocessors 3 and memories 4 in which are recorded software for signing and encrypting and decrypting data, authentication, non-repudiation and message integrity which will be described in more detail in the following.
• the information processing means 2 also comprise working memories and an interface for connection to access means to a data transmission network 6 such as the Internet network for example, for the transfer of data to a data transmission network.
• a data transmission network 6 such as the Internet network for example, for the transfer of data to a data transmission network.
• These means 8 also include working memories and a link interface to means 1 1 of access to the Internet network 6.
• FIGS. 2 and 3 are flowcharts of the main functions implemented in the system of FIG. 1.
• An exchange of data between a cash register and the central server essentially comprises:
• the start-up phase of FIG. 2 essentially comprises, after connection of the cash register and the central server and recognition of the IP address of the cash register by the central server, the sending by the central server to the cashier of an encrypted message including a date and a secret code SC specific to the central server.
• the date and the secret code are mixed, for example by concatenation, and an E footprint is added to the set resulting, this fingerprint being obtained by hashing said set, for example by means of a hash algorithm H of the type SHA (Secure Hash Algorithm).
• the E-date-SC set is then encrypted in the central server, by means of an encryption algorithm, for example of the AES type with a CBC encryption mode, and an encryption key produced by a key generator.
• an encryption algorithm for example of the AES type with a CBC encryption mode
• an encryption key produced by a key generator.
• pseudo-random from data comprising a secret code C specific to the body and a symbolic code specific to the body, for example its MAC (Media Access Control).
• MAC Media Access Control
• the key generator is a pseudo-random generator such as a one-way hash function, for example.
• the encrypted E-date-SC data set is transmitted over the Internet to the cash register which is equipped with the same encryption means as the central server, that is to say a key generator and a encryption algorithm identical to those of the central server.
• the key generator of the cash register generates a decryption key from the same secret code data C and MAC address that used by the central server key generator.
• the encryption algorithm of the cash register can decipher the received message and provide the whole E-date-code SC in clear.
• the fingerprint E makes it possible to check the integrity of this message and the date and code data SC are used for the sending of encrypted messages to the central server as illustrated in FIG.
• the messages to be sent from the cash register to the central server can be stored in a memory 12 (a message table) of the cash register.
• Each message M to be sent is extracted from the table 12 and associated with a fingerprint E generated by applying a hash algorithm H to the message, the fingerprint E having a reduced size compared to that of the message.
• the hash algorithm H is for example of the SHA (Secure Hash Algorithm) type, as used previously by the central server.
• the fingerprint-message assembly E-M is then digitally signed, for purposes of non-repudiation and authentication of the cash by the central server.
• a secret key S signature key
• a pseudo-random key generator 13 from fixed data including a MAC address code of the cash register , the secret code C of the cash register, and the secret code SC of the central server, and variable data including the date and an incremental number of operation j, which characterize the processing of the message M in the following message sending to perform and that change with each new message.
• the signature key S is thus changed at each operation, that is to say at each sending of a message.
• the signed message 14 is then encrypted by means of an encryption algorithm 15, for example of the AES type with a CBC encryption mode, and of an encryption key CH produced by a pseudo-random key generator 16 of the type already indicated. , from the same fixed and variable data as those applied to the signature key generator 13.
• an encryption algorithm 15 for example of the AES type with a CBC encryption mode
• an encryption key CH produced by a pseudo-random key generator 16 of the type already indicated.
• the encryption key CH is thus modified each time a message M is sent, such as the signature key S.
• the encrypted message 17 is transmitted over the Internet to the central server. Upon receipt, it is decrypted by means of a decryption algorithm 18 and a secret decryption key D produced by a pseudo-random key generator 1 9 using the data already mentioned (MAC address of the cash register, code C checkout, server SC code central, date and transaction number j).
• the decryption key generator 19 of the central server is a hash function identical to that of the encryption key generator 16 of the box, and the two generators 18 and 19 are synchronized, by means of the operation number j which is incremented one unit for each new operation.
• the result of the decryption 18 is the signed message 14 to which a hash function is applied with the intervention of an authentication key S produced by a pseudo-random key generator 21 corresponding to the signature key generator 13 of the cash register. and operating with the same data MAC address, C and SC codes, date and operation number, the two key generators 13 and 21 being synchronized by means of the operation number j. It is thus verified that the message M emanates well from the box in question (the criterion of non-repudiation of the sender of the message received by the receiver is then satisfied) and the message M associated with the print E is obtained.
• This acknowledgment message consists of a new date, corresponding to the date of the central server at this time, and a corresponding fingerprint ED produced by a hash algorithm H applied to the new date.
• the date-imprint set is encrypted by means of an encryption algorithm 24 and a key d produced by a pseudo-random generator 25 from the MAC address of the cash register and the secret codes C of the cash register. SC of the central server.
• the encrypted acknowledgment message 26 is sent by the Internet to the box where it is decrypted by means of a decryption algorithm 27 and a key produced by a pseudo-random generator 28 from the MAC address of the cash register and the aforementioned secret codes C and SC.
• the decrypted date data is processed by hashing to obtain a fingerprint that is compared to the ED fingerprint at 29. If the check is positive, the new date replaces the previous date for processing and sending the next message to the receiver.
• the operation number j is reset to zero, which makes it possible to re-synchronize the key generators 13, 16, 19 and 21 for sending new messages.
• the invention thus proposes a fully secure and interactive method and system for exchanging data between an issuer, for example a cash register at a point of sale and a receiver such as a central server, particularly through a public telecommunications network of the Internet type.
• This method and system satisfy the aforementioned criteria of authentication, confidentiality, non-repudiation, integrity and acknowledgment.

Landscapes

• Engineering & Computer Science (AREA)
• Computer Security & Cryptography (AREA)
• Computer Networks & Wireless Communication (AREA)
• Signal Processing (AREA)
• Data Exchanges In Wide-Area Networks (AREA)
• Storage Device Security (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=43807126

Family Applications (1)

Country Status (5)

Families Citing this family (4)

Family Cites Families (18)

• 2010
  • 2010-09-28 FR FR1057785A patent/FR2965431B1/fr active Active
• 2011
  • 2011-09-27 EP EP11773802.1A patent/EP2622785A1/de not_active Withdrawn
  • 2011-09-27 US US13/876,039 patent/US8914640B2/en active Active
  • 2011-09-27 WO PCT/FR2011/052260 patent/WO2012042170A1/fr active Application Filing
• 2013
  • 2013-04-02 IL IL225523A patent/IL225523A/en active IP Right Grant

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events