## Wednesday, November 3, 2021

### Digital Signature | Process of digital Signature | Properties of Digital Signature | Purpose of Digital Signature

What is Digital Signature?

A digital signature is a mathematical technique used to validate the authenticity and integrity of a message or digital document. A digital signature is defined the signature generated electronically from the digital computer to ensure the identity of the sender and content of the message cannot be modified during transmission process.

Purpose of Digital Signature

Concept of digital signature is that sender of a message uses a signing key (Private key) to sign the message and send that message and its digital signature. The receiver uses a verification key (Public key) of the sender only to verify the origin of the message and make sure that it has not been tempered with while in transmission. Digital signature techniques achieve the authenticity and integrity of the data over internet.

 Figure: Concept of Digital Signature

Process of Digital Signature

Hash value of a message when encrypted with the private key of a user is, his digital signature on that e-Document. Digital signature is an example of asymmetric key cryptography which uses three different algorithms to complete the process.

Step – 1: First step is key generation algorithm which generates private key and a corresponding public key.

Step – 2: Next step signing algorithm which selects sending message and a private key generated in step 1, to produce a signature.

Step – 3: Third step is signature verifying algorithm which verifies the authenticity of sending message and public key.

 Figure: Process of Digital Signature

Properties of Digital Signature

In situations where, there is no complete trust between sender and receiver, something more than authentication is needed. The most attractive solution to this problem is the digital signature. The digital signature must have the following properties:

1.      It must verify the author and the date and time of the signature.

2.      It must authenticate the contents at the time of the signature.

3.      It must be verifiable by third parties, to resolve disputes.

Thus, the digital signature function includes the authentication function.

Authentication: Identification of person that signs.

Integrity of data: Every change will be detected.

Non repudiation: Author cannot be denied of his work.

Imposter prevention: Elimination of possibility of committing fraud by an imposter.

Expiry: In this era of fast technology, many of these tech products have a short life.

Certificates: In order to effectively use of digital signatures, both senders and receivers may have to buy digital certificates.

Software: To work with digital certificates/digital signatures, senders and receivers have to buy verification software or pay to third party for verification.