Consider the following statements regarding digital signatures under the IT Act, 2000: 1. A digital signature uses an asymmetric crypto system. 2. A digital signature must involve a hash function. 3. The private key and public key together constitute a key pair unique to the subscriber.  Which of the statements given above are correct?

Section 3 of the IT Act defines digital signatures as authentication using an asymmetric cryptosystem and a hash function. Asymmetric cryptography necessarily involves a mathematically linked public key and private key, collectively known as a key pair, which is unique to the subscriber. The hash function ensures integrity of the electronic record by converting data into a fixed-length hash value. Since all three statements accurately describe statutory and technical elements of a digital signature, option D is correct.