Method of encryption, method of decryption, corresponding computer device and program

Patent metadata

Field	Value
Publication number	US-11075756-B2
Application number	US-201716341281-A
Country	US
Kind code	B2
Filing date	Oct 12, 2017
Priority date	Oct 12, 2016
Publication date	Jul 27, 2021
Grant date	Jul 27, 2021

Abstract

A method of encryption of a message implemented by an electronic encryption device. The method includes: obtaining a current message; obtaining a current encryption key; determining, from a plurality of variants a basic encryption protocol, of a current variant of the encryption protocol; encrypting, by using the current variant and the encryption key, the message to be encrypted, delivering an encrypted message; and transmitting the encrypted key.

First claim

The invention claimed is:

1. A method of encryption of a message implemented by an electronic encryption device, wherein the method comprises:
obtaining a current message;
obtaining a current encryption key;
determining, from a plurality of variants of a basic encryption protocol, a current variant of said basic encryption protocol;
encrypting, by using said current variant and said encryption key, said message to be encrypted, delivering an encrypted message; and
transmitting said encrypted message,
wherein said determining a current variant of the encryption protocol comprises:
obtaining at least one variation index of at least one parameter of the encryption protocol; and
assigning a value, by using said at least one variation index, to said at least on parameter of said basic encryption protocol, delivering said current variant,

and wherein said at least one parameter of said encryption protocol comprises: a variation of a size of at least one variable, a variation of a position of at least one variable, a variation of a type of equation, a variation of a sign of at least one variable, or an adjoining of at least one additional function.

2. The method of encryption according to claim 1 , further comprising transmitting at least one piece of data representing said current variant of said encryption protocol.

3. The method of encryption according to claim 1 , wherein said basic encryption protocol is the ElGamal protocol represented by the equation:
m=xr+ks (mod p− 1)
an equation wherein:
m is the current message;
x is the current encryption key;
s is the encrypted message;
k is a random number;
r=alpha{circumflex over ( )}k (mod p) where alpha is a generator of Z_p and Z_p is a ring of relative integers modulo p where p is a prime number.

4. The method of encryption according to claim 1 , wherein said at least one index of variation is a random number.

5. The method of encryption according to claim 1 , wherein said at least one variation index, used for the encryption of the current message, is different from a variation index used for the encryption of the preceding message.

6. An electronic device for encryption of a message, wherein the electronic device comprises:
a processor; and
a non-transitory computer-readable medium comprising instructions stored thereon, which when executed by the processor configure the electronic device to perform acts comprising:
obtaining a current message;
obtaining a current encryption key;
determining, from among a plurality of variants of a basic encryption protocol, a current variant of said basic encryption protocol;
encrypting, by using said current variant and said encryption key, said message to be encrypted, delivering an encrypted message; and
transmitting said encrypted message,
wherein said determining a current variant of the basic encryption protocol comprises:
obtaining at least one variation index of at least one parameter of the basic encryption protocol; and
assigning a value, by using said at least one variation index, to said at last one parameter of said basic encryption protocol, delivering said current variant,

and wherein said at least one parameter of said encryption protocol comprises: a variation of a size of at least one variable, a variation of a position of at least one variable, a variation of a type of equation, a variation of a sign of at least one variable, or an adjoining of at least one additional function.

7. A non-transitory computer-readable medium comprising a computer program product stored thereon, which comprises program code instructions for executing a method of encryption, when the instructions executed by a processor of an electronic device, wherein the instructions configure the electronic device to perform acts comprising:
obtaining a current message;
obtaining a current encryption key;
determining, from a plurality of variants of a basic encryption protocol, a current variant of said basic encryption protocol;
encrypting, by using said current variant and said encryption key, said message to be encrypted, delivering an encrypted message; and
transmitting said encrypted message,
wherein said determining a current variant of the basic encryption protocol comprises:
obtaining at least one variation index of at least one parameter of the basic encryption protocol; and
assigning a value, by using said at least one variation index, to said at least one parameter of said basic encryption protocol, delivering said current variant,

and wherein said at least one parameter of said encryption protocol comprises: a variation of a size of at least one variable, a variation of a position of at last one variable, a variation of a type of equation, a variation of a sign of at least one variable, or an adjoining of at least one additional function.

Assignees

• Ingenico Group

Inventors

• Beunardeau Marc
• Geraud Remi
• Naccache David
• Connolly Aisling

Classifications

• H04L9/002

  Countermeasures against attacks on cryptographic mechanisms (network architectures or network communication protocols for protection against malicious traffic H04L63/1441) · CPC title

• H04L63/0428 Primary

  wherein the data content is protected, e.g. by encrypting or encapsulating the payload · CPC title

• H04L9/3013 Primary

  involving the discrete logarithm problem, e.g. ElGamal or Diffie-Hellman systems · CPC title