Patent ID: 7664957

Claim:
A system-implemented method of generating a first digital signature on a document D, the system comprising circuitry, the method comprising generating, by the circuitry, a signal representing a sum S1 of a plurality of terms of a predefined cyclic group G1, said terms comprising k terms: C 1*( s*P 1), C 2*( s*P 2), . . . Ck* ( s*Pk ), wherein: k and s are predefined integers independent of the document D, and k>1; C1, . . . Ck are integers, wherein at least two of C1, . . . Ck are different from each other, wherein at least one of C1, . . . Ck depends on the document D; P1, . . . Pk are k different elements of the group G1 which are independent of the document D; “*” denotes multiplication by an integer of an element of the group G1.