Digital Signature Algorithm

The Digital Signature Algorithm, or DSA, is a public key cryptosystem and a United States Federal Information Processing Standard for producing digital signatures, based on modular exponentiation and the difficulty of the discrete logarithm problem. A signer holding a private key produces a signature that anyone holding the matching public key can verify, and DSA is a variant of the earlier Schnorr and ElGamal signature schemes. The National Institute of Standards and Technology proposed DSA in 1991 and adopted it as FIPS 186 in 1994, publishing five later revisions before eventually withdrawing its approval for DSA signature generation.