cryptography Cryptography, or cryptology (from grc, , translit=kryptós "hidden, secret"; and ''graphein'', "to write", or ''-logia'', "study", respectively), is the practice and study of techniques for secure communication in the presence of adver ...

, the Pointcheval–Stern signature algorithm is a

digital signature A digital signature is a mathematical scheme for verifying the authenticity of digital messages or documents. A valid digital signature, where the prerequisites are satisfied, gives a recipient very high confidence that the message was created b ...

scheme based on the closely related

ElGamal signature scheme The ElGamal signature scheme is a digital signature scheme which is based on the difficulty of computing discrete logarithms. It was described by Taher Elgamal in 1985. (conference version appeared in CRYPTO'84, pp. 10–18) The ElGamal signature ...

. It changes the ElGamal scheme slightly to produce an algorithm which has been proven secure in a strong sense against

adaptive chosen-message attack A digital signature is a mathematical scheme for verifying the authenticity of digital messages or documents. A valid digital signature, where the prerequisites are satisfied, gives a recipient very high confidence that the message was created b ...

s, assuming the

discrete logarithm problem In mathematics, for given real numbers ''a'' and ''b'', the logarithm log''b'' ''a'' is a number ''x'' such that . Analogously, in any group ''G'', powers ''b'k'' can be defined for all integers ''k'', and the discrete logarithm log''b'' ...

is intractable in a strong sense.

David Pointcheval David Pointcheval is a French cryptographer. He is currently a Senior Researcher at CNRS. He is head of the Computer Science Department and Cryptography Laboratory at the École normale supérieure. He is mainly known for his contributions in the a ...

and

Jacques Stern Jacques Stern (born 21 August 1949) is a cryptographer, currently a professor at the École Normale Supérieure. He received the 2006 CNRS Gold medal. His notable work includes the cryptanalysis of numerous encryption and signature schemes, th ...

developed the ''

forking lemma The forking lemma is any of a number of related lemmas in cryptography research. The lemma states that if an adversary (typically a probabilistic Turing machine), on inputs drawn from some distribution, produces an output that has some property wi ...

'' technique in constructing their proof for this algorithm. It has been used in other security investigations of various cryptographic algorithms.

References

Digital signature schemes Public-key cryptography {{crypto-stub