Patent ID: 7945044

Claim:
A method for performing an untraceable secret matching between at least a first credential associated with a first property of a first user and a second credential associated with a second property of a second user within a network system, wherein the matching performed on a side of the first user comprises: receiving using a secure channel the first credential from an authentication component upon verification that the first user possesses the first property; receiving using a secure channel a matching reference from a policy manager component upon verification that the first user is entitled to perform the matching, the matching reference being formed such that the first user can detect a matching of the first property with a remote property from a credential of another user during a handshake; supplying a first nonce value to the second user; receiving a hidden version of the second credential from the second user, the hidden version being formed by the second user on the basis of the second credential, the first nonce value supplied by the first user and at least one random value locally generated on a side of the second user; and performing the matching by combining the first credential and the received hidden version of the second credential with the first nonce value and by comparing the combination with the matching reference, wherein: the first and the second credentials are formed according to the following formula: Credential( d )= F ( K, d ) wherein d is a description of the respective property, F is a pseudorandom bit permutation and K is a random value in a key space of F, and the hidden version of the second credential is formed according to the following formula: {( n A r B,1 r B,2 )· P ,( r B,1 r B,2 )· Q ( r B,1 b)· P,r B,2 ·Q} wherein n A is a nonce value supplied by the first user, r b,1 and r B,2 are two locally generated random values, generated by the second user B and b·P represents the credential of the second user B.