Patent BE-1017304-A6 (BE)
Title: Generating security code comprising one time password or digital signature, for e.g. internet banking, by transforming dynamic value with cryptogram obtained using asymmetric operation with private key
Inventor: COULIER FRANK
Filed: 2008-02-05
Granted: 2008-05-06
Abstract: A dynamic intermediate value is created using one or more variable input data and a cryptographic algorithm comprising at least one secret, and then this value is transformed into the code. An asymmetric cryptographic operation is carried out using a private key, producing a cryptogram for transforming the dynamic value. The transformation involves producing a security code with a size which is less than that of a cryptogram generated by the asymmetric cryptographic operation step. The variable input data comprises a time value, a teller value, a challenge value or transaction data, or a combination thereof. Independent claims are also included for the following: (1) Method for validating a security code for authenticating a user, comprising an OTP (One Time Password) or MAC (Message Authentication Code) signature, by creating a reference cryptogram using a reference cryptographic algorithm applied to one or more reference input data with the aid of a server key which is a function of the value of a PKI (Public Key Infrastructure) private key of an authentic user, the reference cryptographic algorithm and the one or more reference input data selected being identical to the other elements used by the authentic user to create the security code; and either processing the reference cryptogram by transforming it into a reference security code with a size less than that of the reference cryptogram, and comparing the reference security code with the actual security code; or treating the reference cryptogram as the security code in order to produce a modified reference cryptogram and a modified security code, and comparing the modified reference cryptogram with the modified security code; (2) Method for validating a security code for authenticating a user which is generated by the first method, by creating a reference cryptogram using a reference cryptographic algorithm applied to one or more reference input data with the aid of a server key, this key, algorithm and the one or more reference input data selected being identical to the other elements used by the authentic user to create the security code; processing the reference cryptogram by transforming it into a reference security code with a size less than that of the cryptogram generated by the asymmetric cryptographic operation; processing the security code to produce a modified security code; comparing the reference security code with the modified security code; and determining the validity of the security code on the basis of these comparison results; and (3) Method for authenticating multiple users each possessing at least one smartcard comprising one or more PKI private keys and capable of performing asymmetric cryptographic operations using these keys, by generating a server key for each smartcard; receiving security codes from the users which comprise OTC's or MAC's; and authenticating the users by validating the received security codes according to the second validation method described above.