Information Technology (Certifying Authorities) Rules, 2000
3. The manner in which information be authenticated by means of Digital Signature.- A Digital Signature shall,-
(a) be created and verified by cryptography that concerns itself with transforming electronic record into seemingly unintelligible forms and back again;
(b) use what is known as "Public Key Cryptography", which employs an algorithm using two different but mathematical related "keys" – one for creating a Digital Signature or transforming data into a seemingly unintelligible form, and another key for verifying a Digital Signature or returning the electronic record to original form, the process termed as hash function shall be used in both creating and verifying a Digital Signature.
Explanation : Computer equipment and software utilizing two such keys are often termed as "asymmetric cryptography".