A digital signature is a mathematical scheme for verifying the authenticity of a digital message or documents. It is used to authenticate the identity of the sender and it confirms the document or message received by the receiver is unaltered. The importance of authentication is increasing due to increase of online transactions over the internet. There is a need to develop a framework for the authentication of computer-based information. A valid digital signature gives a recipient reason to believe that the message was created by a known sender, and that it was not altered in transit. Digital signatures are commonly used for any electronic transaction like software distribution, financial transactions, and in other cases where it is important to detect forgery or tampering. Various asymmetric cryptosystems create and verify digital signatures using different algorithms and procedures. This paper is a survey of various Digital Signature schemes, number theoretic based (RSA, DSA and EIGamal) as well as lattice based cryptography. Lattice-based cryptographic constructions are based on the presumed hardness of lattice problems. The goal of this paper is to make a comparative study between number theoretic and lattice based digital signature schemes.
