What is a digital signature in cryptography?

A digital signature uses cryptographic keys to sign a document. RSA algorithm is used to generate a pair of keys known as the public key and private key that are mathematically linked to one another.

A digital signature generally uses Public Key Infrastructure (PKI), a framework to manage the public key of sender and receiver. Asymmetric cryptography and PKI are used in digital signatures to give an extra layer of protection to the message.

A private key is used by the sender to encrypt the data and send the digital signature. As the name suggests, the private key is kept secure in the sender's hardware and is known only to the sender. The recipient uses the sender's public key to decrypt the message. If the message decrypts then the message is untampered. The receiver can verify the digital signature with the sender's public key.

Digital signature in cryptography performs two important functions:

  • Establish sender identity.
  • Make the signer's public key available.

The signer requires a digital signature certificate issued by a certifying authority to store the authenticated personal information. A digital signature certificate is important to produce a legally binding digital signature. A signer can apply for a digital signature certificate on eMudhra Digital website and generate a digital signature certificate within 30 minutes.