ABSTRACT
A digital signature scheme is a part of asymmetric cryptosystem which offers method of signing a message using private key and its verification using public key. Digital signature is a cryptographic primitive which can help to achieve authentication, integrity and non-repudiation. As Digital Signature Algorithm (DSA) is a variant of ElGamal signature, hence all the security concerns of ElGamal signature are recommended for DSA also. In particular, to avoid the existential forgery, the use of cryptographic hash function is strictly recommended. Digital signature is one of the most useful primitives used for authentication. The Rivest–Shamir–Adleman (RSA) signature scheme is based on the parameters of the RSA cryptosystem. The ElGamal signature scheme is based on the parameters of the ElGamal cryptosystem. The Elliptic Curve Digital Signature Algorithm is the elliptic curve analogue of the DSA.
