How can you trust the document you receive or send over the internet?? What if they change the document midway?? What if they send you a different contract and you receive a different one?? Sounds scary?? But don’t worry the answer to this is here- the digital signature.

What is a digital signature??

A digital signature is basically a mathematical way of checking the originality of a digital document. It is like a document verification process.  It checks that a known sender has generated the received document. Once verified, sender cannot deny sending the document. The document received is the original document, no one has changed it during the transfer. So this is the basic idea of a digital signature.

The technology behind digital signatures

The digital signature works on 3 basic simple algorithms- The key generation algorithm, the signing algorithm and the signature verifying algorithm.

The key generation algorithm selects a private key from a set of keys. It also generates a corresponding public key.

The signing algorithm produces a signature using this private key and the message that is to be delivered. It actually adds a code along with the document that will help in its authentication.

The signature verifying algorithm is the last step. The input to the last algorithm is the message, the public key, and the signature. This algorithm checks the authenticity of the document. Once the algorithm proves it to be authentic, the job is done!

So, in short, we can say that the digital signature is like a lock with two keys. One key to lock and the other to unlock. All this takes place mathematically so it definitely isn’t as easy as it seems to be.

Importance of Digital Signatures

Digital signatures also keep record of the transactions. It stores the Meta data of the path it followed. The signature records the IP addresses of the devices that accessed the document, the precise time and the location too. If anything goes wrong with the document, this data can help to find the point of error.

Types of Digital Signatures.

There are a few types of digital signatures in practice today. 

Certified signatures:
A certified signature means that you are the rightful author of that document and you do not want someone to alter its content. It is shown by the blue ribbon on the top left of pdf.

Approval Signatures:
Approval signatures are used in business workflow. The approved documents have a seal embedded in them. Once the seal is embedded no other proof of approval is required. It makes the approval verification process easy.

Visible and Invisible Signatures:
Visible signatures are same as signatures made with pens. They can be seen in the document. In-visible signatures are made when you do not want your signatures to be viewed.


Indian constitution has 3 pillars – Democracy, Executive and Judiciary. The e-transaction world runs on three pillars- Authentication, Integrity, and Non-denial. The digital signature helps us protect these three pillars and develop in user a feeling of trust and security.