In cryptography, the Pointcheval-Stern signature algortihm is a digital signature scheme based on the closely related ElGamal scheme. It changes the ElGamal scheme slightly to produce an algorithm which has been proven secure in a strong sense against adaptive chosen-plaintext attacks. That is, if the discrete logarithm problem is intractible in a strong sense. (D Pointcheval and J Stern. Security proofs for signature schemes. in U Maurer, ed. Adv in Crypt -- Eurocrypt '96, 387-398, Springer-Verlag, 1996. Lect Notes in Comp Sci, nr 1070); and D Pointcheval and J Stern, Security arguments for digital signatures and blind signatures, J Crypt 13(3):361-396, 2000.)

David Pointcheval and Jacques Stern developed the forking lemma technique in constructing thier proof for this algorithm. It has been used in other security investigations of various cryptographic algorithms.