Cryptographic authentication process

• US 20040177252A1
• Filed: 12/23/2003
• Published: 09/09/2004
• Est. Priority Date: 06/27/2001
• Status: Active Grant

• Current Assignee: Orange S.A.
• Original Assignee: Orange S.A.
• Inventors: Vallee, Luc, Petit, Stephane
• Granted Patent: US 7,451,314 B2
• Time in Patent Office: Days
• US Class Current: 713/170
• CPC Class Codes: H04L 2209/56 Financial cryptography, e.g. electronic payment or e-cash
• CPC Class Codes: H04L 9/3247 involving digital signatures

Abstract

The invention relates to a cryptographic authentication method including a first step a) during which a first entity (A) to be authenticated sends an authenticator second entity (B) a message protected by a cryptographic algorithm and a secret key (K_S). During a second step b), the second entity (B), after receiving said message, carries out operations selected from the group comprising completely verifying the authentication of the received protected message by means of said cryptographic algorithm and a verification key (K_V), delaying said complete verification, partly verifying said authentication, partly verifying said authentication and completing the verification subsequently, and omitting to verify said authentication, one of said operations being chosen as a function of the degree of certainty that the second entity (B) wishes to obtain as to the authentication of the first entity (A) and being concealed from the first entity (A).

Claims

1. A cryptographic authentication method including a first step a) during which a first entity (A) to be authenticated sends an authenticator second entity (B) a message protected by a cryptographic algorithm and a secret key (K_S),

which method is characterized in that:

it includes a second step b) during which the second entity (B), after receiving said message, carries out an operation selected from the group comprising;

completely verifying the authentication of the received protected message by means of said cryptographic algorithm and a verification key (K_V),

delaying complete verification of the authentication of said protected message,

partly verifying the authentication of the received protected message by means of said cryptographic algorithm and said verification key (K_V),

partly verifying the authentication of the received protected message by means of said cryptographic algorithm and said verification key (K_V) and completing the verification subsequently, and

omitting to verify the authentication of said protected message,

and in that one of said operations is chosen as a function of the degree of certainty that the second entity (B) wishes to obtain as to the authentication of the first entity (A) and is concealed from the first entity (A).

2. A method according to claim 1, wherein the cryptographic algorithm is a public key (K_V) algorithm.

3. A method according to claim 2, wherein the cryptographic algorithm is an RSA algorithm in which the public key (K_V) is a function of a modulus (n).

4. A method according to claim 3, wherein the protected message has a length that is at most equal to half the modulus (n) of said public key.

5. A method according to claim 2, wherein the cryptographic algorithm is a DSA algorithm.

6. A method according to claim 2, wherein the cryptographic algorithm is a zero knowledge algorithm.

7. A method according to claim 1, wherein the cryptographic algorithm is a secret key (K_S) algorithm.

8. A method according to any of claims 1 to 7, wherein the first entity (A) is a client and the second entity (B) is a server.

9. A server employed in the method according to claim 8, characterized in that it includes:

first verification means (V1) able to verify completely the authentication of the received protected message by means of said cryptographic algorithm and a verification key (K_V),

second verification means (V2) able to verify partially the authentication of the received protected message by means of said cryptographic algorithm and said verification key (K_V),

a database (BD) containing one or more parameters assigned a risk value (R), and

switching means (AIG) for switching received protected messages to the first verification means (V1) or to the second verification means (V2) as a function of comparing the content of the received protected messages and a parameters or parameters from the data base (BD).