Cryptographic method for protection against fraud
First Claim
1. A cryptographic method of providing protection against fraud in transactions between an application (1) and an electronic chip (2) of a user, the method comprising the following steps:
- determining a non-linear pseudo random function f known to the application (1) and implanted (4) in the electronic chip (2),allocating to the electronic chip (2) a first secret key K known only to the electronic chip (2) and to the application (1) and kept secret (5) in the electronic chip (2),on each authentication of the electronic chip (2), generating a variable input word R referred to as a random seed,computing (15,16) by both the electronic chip (2) and the application (1) a certificate (Sp, S) which is the result of applying the non-linear pseudo random function f to a list of arguments (e1, e2) comprising at least the seed R and the secret key K,allocating to the electronic chip (2) a second secret key K′
known only to the electronic chip (2) and to the application (1) and kept secret (6) in the electronic chip (2),on each authentication of the electronic chip (2), determining (17, 18) a mask M computed from at least a portion of the secret key K′
,masking (19) the value of the certificate (Sp) by means of the mask M to provide a second layer of security such that only the masked value of the certificate (Spm) is made available to the application (1), andusing the application (1) to verify the masked value of the certificate (Spm) computed by the electronic chip (2).
1 Assignment
0 Petitions
Accused Products
Abstract
A cryptographic method of protection against fraud in transactions between an application and an electronic chip of a user. Both the electronic chip and the application compute a certificate (Sp, S) which is the result of applying a non-linear function f to a list of arguments (e1, e2) comprising at least a seed R and a secret key KO. A second secret key K′ which is known only to the electronic chip and to the application is allocated to and kept secret in the electronic chip. Upon each authentication of the electronic chip, a mask M is determined by computing it from at least a portion of the secret key K′. The value of the certificate (Sp) is masked by means of the mask M to make available to the application only the masked value of the certificate (Spm). The application is used to verify the masked value of the certificate (Spm) computed by the electronic chip.
-
Citations
20 Claims
-
1. A cryptographic method of providing protection against fraud in transactions between an application (1) and an electronic chip (2) of a user, the method comprising the following steps:
-
determining a non-linear pseudo random function f known to the application (1) and implanted (4) in the electronic chip (2), allocating to the electronic chip (2) a first secret key K known only to the electronic chip (2) and to the application (1) and kept secret (5) in the electronic chip (2), on each authentication of the electronic chip (2), generating a variable input word R referred to as a random seed, computing (15,16) by both the electronic chip (2) and the application (1) a certificate (Sp, S) which is the result of applying the non-linear pseudo random function f to a list of arguments (e1, e2) comprising at least the seed R and the secret key K, allocating to the electronic chip (2) a second secret key K′
known only to the electronic chip (2) and to the application (1) and kept secret (6) in the electronic chip (2),on each authentication of the electronic chip (2), determining (17, 18) a mask M computed from at least a portion of the secret key K′
,masking (19) the value of the certificate (Sp) by means of the mask M to provide a second layer of security such that only the masked value of the certificate (Spm) is made available to the application (1), and using the application (1) to verify the masked value of the certificate (Spm) computed by the electronic chip (2). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
-
-
18. A cryptographic method of providing protection against fraud in transactions between an application (1) and an electronic chip (2) of an user, the method comprising the following steps:
-
determining a non-linear pseudo random function f known to the application (1) and implanted (4) in the electronic chip (2), allocating to the electronic chip (2) a first secret key K known only to the electronic chip (2) and to the application (1) and kept secret (5) in the electronic chip, on each authentication of the application (1), generating an input word R referred to as a random seed, computing by both the electronic chip (2) and the application (1) a certificate (Sp, S) which is the result of applying the non-linear pseudo random function f to a list of arguments (e1, e2) comprising at least the seed R and the secret key K, allocating to the electronic chip (2) a second secret key K′
known only to the electronic chip (2) and to the application (1) and kept secret (6) in the electronic chip (2),on each authentication of the application (1), determining a mask M computed from at least a portion of the secret key K′
,masking the value of the certificate (S) by means of the mask M to provide a second layer of security such that only the masked value (Sm) of the certificate (5) is made available to the electronic chip (2), and using the electronic chip (2) to verify the masked value (Sm) of the certificate (S) computed by the application (1). - View Dependent Claims (19, 20)
-
Specification