What do you understand by Digital Signature? What information does a Digital Signature contain ?

As per section 2(1)(p) of the Information Technology Act, 2000 "Digital signature" means authentication of any electronic record by a subscriber by means of an electronic method or procedure in accordance with the provisions of section 3. A Digital signature (standard electronic signature) takes the concept of traditional paper-based signing and turns it into an electronic "fingerprint". This fingerprint or coded message, is unique to both the document and the signer and binds both of them together. The digital signature ensures the authenticity of the signer. Any changes made to the document after it is signed invalidate the signature, thereby protecting against signature forgery and information tampering. Digital signatures help organizations to sustain signer authenticity, accountability, data integrity and non-repudiation of electronic documents and forms. A digital signature/electronic signature typically contains the: Owner's public key, the Owner's name, Expiration date of the public key, the Name of the issuer (the Certifying Authority that issued the Digital ID), Serial number of the digital signature, and the digital signature of the issuer.