Method for the encryption of payment means data, corresponding payment means, server and programs

1. A method for verifying the validity of a piece of payment means data for implementing a payment transaction between a payment means comprising a data processor and a processing server comprising a data processor, wherein the method comprises:

a phase for encrypting the piece of payment means data, implemented by the payment means, comprising:

obtaining a current piece of payment means data from a memory of the payment means;

generating a following piece of payment means data as a function of the current piece of payment means data and as a function of a public encryption key n of the payment means, the generating relying on the use of a Rabin asymmetric encryption protocol, said public encryption key n being the product of two large prime integers p and q;

transmitting the following piece of payment means data to the processing server; and

replacing the current piece of payment means data by the following piece of payment means data within the memory of the payment means, the following piece of payment means data becoming the current piece of payment means data for a subsequent iteration of the obtaining, generating, transmitting and replacing; a phase for verifying the validity of the following piece of payment means data, implemented by the processing server, comprising:

obtaining the following piece of payment means data from the payment means;

obtaining a piece of payment means reference data from a memory of the processing server;

computing, using the Rabin asymmetric encryption protocol, from the piece of payment means reference data, as a function of a predetermined time period:

a predetermined number of following codes, using the public encryption key n of the payment means; and

a predetermined number of the preceding codes, using the large prime integers p and q defining a private key of the payment means;

delivering payment means comparison data, forming a set of reference data; and

comparing the following piece of payment means data with the data of the set of reference data, delivering an assertion of validity of the following piece of payment means data when the following piece of payment means data is identical to one of the pieces of data of the set of reference data.

2. The method according to claim 1 , wherein generating a following piece of payment means data comprises the implementing of an encryption function such that the following piece of payment means data depends on the encryption function, said encryption function comprising the obtaining of:

the square of the current piece of payment means data; and

the square modulo the encryption key.

3. The method according to claim 1 , wherein said encryption function is a verification code.

4. The method according to claim 1 , wherein the method further comprises displaying said following piece of payment means data on a screen of said payment means.

5. The method according to claim 1 , wherein the method further comprises transmitting said following piece of payment means data to a payment terminal.

6. A non-transitory computer readable memory comprising a computer program stored thereon, including program code instructions for implementing a phase for encrypting a piece of payment means data of a method for verifying the validity of the piece of payment means data for implementing a payment transaction between a payment means and a processing server, when the program is executed by a processor of the payment means, wherein the program code instructions are configured to:

obtain a current piece of payment means data from a secure memory of the payment means;

generate a following piece of payment means data as a function of the current piece of payment means data and as a function of a public encryption key n of the payment means, said generating relying on the use of a Rabin asymmetric encryption protocol, said public encryption key n being the product of two large prime integers p and q;

transmit the following piece of payment means data to a processing server; and

replace the current piece of payment means data by the following piece of payment means data within the memory of the payment means, the following piece of payment means data becoming the current piece of payment means data for a subsequent iteration of the obtaining, generating, transmitting and replacing.

7. A non-transitory computer readable memory comprising a computer program stored thereon including program code instructions for implementing a phase for verifying the validity of a piece of payment means data of a method for verifying the validity of the piece of payment means data for implementing a payment transaction between a payment means and a processing server, when the program is executed by a processor of the processing server, wherein the program code instructions are configured to:

obtain a following piece of payment means data from the payment means;

obtaining a piece of payment means reference data from a memory of the processing server;

compute, using a Rabin asymmetric encryption protocol, from the piece of payment means reference data, as a function of a predetermined time period:

a predetermined number of following codes, using a public encryption key n of the payment means; and

a predetermined number of the preceding codes, using large prime integers p and q defining a private key of the payment means, n being the product of p and q;

delivering payment means comparison data, forming a set of reference data;

compare the following piece of payment means data with the data of the set of reference data, delivering an assertion of validity of the following piece of payment means data when the following piece of payment means data is identical to one of the pieces of data of the set of reference data.

8. A system for verifying the validity of a piece of payment means data for implementing a payment transaction, the system comprising:

a payment means comprising encryption means that can be actuated iteratively and a data payment processor which is configured to:

obtain a current piece of payment means data from a secure memory of the payment means;

generate a following piece of payment means data as a function of the current piece of payment means data and as a function of a public encryption key n of the payment means, said generating relying on the use of a Rabin asymmetric encryption protocol, said public encryption key n being the product of two large prime integers p and q;

transmit the following piece of payment means data to a processing server; and

replace the current piece of payment means data by the following piece of payment means data within the memory of the payment means, the following piece of payment means data becoming the current piece of payment means data for a subsequent iteration of the obtaining, generating, transmitting and replacing;

a processing server comprising means of cryptographic processing capable of enabling a verification of the validity of a piece of payment means data, and a data processor which is configured to:

obtain the following piece of payment means data from the payment means;

obtaining a piece of payment means reference data from a memory of the processing server;

compute, using the Rabin asymmetric encryption protocol, from the piece of payment means reference data, as a function of a predetermined time period:

a predetermined number of following codes, using the public encryption key n of the payment means; and

a predetermined number of the preceding codes, using the large prime integers p and q defining a private key of the payment means;

delivering payment means comparison data, forming a set of reference data;

compare the following piece of payment means data with the data of the set of reference data, delivering an assertion of validity of the following piece of payment means data when the following piece of payment means data is identical to one of the pieces of data of the set of reference data.