One way authentication
A cryptosystem prevents replay attacks within existing authentication protocols, susceptible to such attacks but containing a random component, without requiring modification to said protocols. The entity charged with authentication maintains a list of previously used bit patterns, extracted from a portion of the authentication message connected to the random component. If the bit pattern has been seen before, the message is rejected; if the bit pattern has not been seen before, the bit pattern is added to the stored list and the message is accepted.
1. A method for a correspondent confirming originality and authenticity of a signed message generated and signed by another correspondent, the method comprising:
said correspondent receiving from said other correspondent said signed message, said signed message comprising information and a signature signing said information;
a cryptographic processor of said correspondent:
performing a RSA operation on said signature and a public exponent of said other correspondent and converting a result of said RSA operation into an alleged bracketed hash E′;
hashing said alleged bracketed hash E′ and splitting a hash result into an alleged masked output and an alleged hash of said information;
extracting alleged random bytes from said alleged masked output and said alleged hash of said information; and,
comparing said alleged hash of said information with a hash of said alleged bracketed hash and said alleged random bytes, and verifies said signature when said hash and said alleged hash of said information agree; and,
confirming said verified signature when an extracted subset of said number does not match a previously stored list of subsets for said correspondent.
2. The method according to claim 1 wherein said previously stored list of subsets is maintained in a database one of said correspondent.
3. The method according claim 2 wherein when said extracted subset is not matched to said previously stored list of subsets, said method further comprises said correspondent adding said extracted subset to said database.
4. The method according to claim 1 wherein said previously stored list of subsets comprises bit patterns obtained from other correspondents.
5. The method according to claim 1 wherein said signature computed by said other correspondent comprises a result of a first RSA operation performed on an encoded message and a private exponent of said other correspondent, and said signed message comprises a combination of said encoded message and said signature.
6. A computing device comprising a processor and a memory, said computing device being connectable to a data communication system, and being configured to execute the method of claim 1 .
7. A method for a correspondent confirming originality and authenticity of a signed message generated and signed by another correspondent, the method comprising:
said correspondent receiving from said other correspondent said signed message, said signed message comprising information I, and a signature comprising a first signature component r, and a second signature component s;
a cryptographic processor of said correspondent:
computing an ephemeral public key kP by calculating s −1 (H(I)P+rA), where k is a private key, P is a generating point of order n, H is a cryptographic hash function, and A is a long term public key of said other correspondent;
converting a first co-ordinate of kP into an integer;
comparing said first co-ordinate to said first signature component r for correspondence;
extracting a subset ƒ(r) from said first signature component r;
comparing said subset ƒ(r) with a list of subsets previously stored by said correspondent; and,
verifying said signature when said first co-ordinate corresponds with said first signature component r, and accepting said verification when said subset ƒ(r) is not in the list.
8. The method according to claim 7 wherein said previously stored list of subsets is maintained in a database one of said correspondent.
9. The method according claim 8 wherein when said extracted subset is not matched to said previously stored list of subsets, said method further comprises said correspondent adding said extracted subset to said database.
10. The method according to claim 7 wherein said previously stored list of subsets comprises bit patterns obtained from other correspondents.
11. The method according to claim 7 wherein said signature computed by said other correspondent comprises a result of a ECDSA signature operation performed by solving a signing equation ks=H(I)+dr(mod n), where d is a long term private key of said correspondent.
12. A computing device comprising a processor and a memory, said computing device being connectable to a data communication system, and being configured to execute the method of claim 7 .