
Public-Key Cryptography ◾ 305
computing a discrete logarithm. It was rst described by Taher ElGamal
in a 1985 paper, “A Public-Key Cryptography and a Signature Scheme,”
in which he proposed the design of the ElGamal cryptography and the
ElGamal signature scheme. e ElGamal signature scheme is nondeter-
ministic. is means that there are many valid signatures for any given
message. e verication algorithm must be able to accept any of these
valid signatures. e ElGamal signature scheme must not be confused with
ElGamal cryptography. All ElGamal signature schemes are designed spe-
cically for the purpose of signature, as opposed to the RSA ...