Q.What is a digital signature? How does it ensure authentication and integrity of an electronic record?

A digital signature is the online equivalent of a handwritten signature, but built on cryptography rather than ink.

A digital signature is a means of authenticating an electronic record, given legal force by Section 3 of the IT Act, 2000. It is created using two techniques together:

• Asymmetric cryptography (a key pair): the signer has a private key, kept secret, and a matching public key, known to others. The record is signed with the private key and verified with the public key.
• A hash function: this produces a short, unique 'fingerprint' (hash) of the record's contents.

It provides two guarantees:

1. Authentication (who signed): because only the signer possesses the private key, a valid signature proves the record came from that signer. The signer's identity is vouched for by a Digital Signature Certificate issued by a licensed Certifying Authority. …

Students often say a digital signature is a scanned handwritten signature — that is a digitised signature and is wrong. Also, do not forget to explain *b …