What is Digital Signature?

What is digital signature? Digital signature is a technique to make sure that electronic documents such as text file, spreadsheet, and e-mail are genuine. Digital signature algorithm depends upon certain kinds of encryption to guarantee authentication. Encryption is the method of taking all the data, which one computer is transferring to another and coding it into such a form that the other computer will only be able to decode. While authentication is, the method of confirming that information is really coming from a reliable source. Both these methods work together for digital signature.

How Digital Signature works?

The functions of digital signature for electronic documents are the same, as that of handwritten signature for printed documents. The signature is an inseparable part of data, which affirms that a particular individual wrote or else approved the document to which is attached the signature. Digital signature in reality provides security of a higher degree than a signature, which is handwritten.


The receiver of a message, which has a digital signature, can validate both that since the signing of the message there has been no change in it either accidentally or intentionally as well as that it has come from the individual whose signature has come as attachment. Furthermore, it is not possible to repudiate secure digital signature since the individual who has signed the document cannot refuse later to admit it by saying that the signature was bogus or forged.

This means, digital signing allows authentication of digital messages, which assures the recipient of a digital message of not only the reliability of the message but also the identity of the sender. Digital signature depends on public key or asymmetric cryptography. In order to generate a digital signature, an individual needs to sign the message with his private key. In this way, digital signature then becomes a part of his message.

By including digital signature in his message, there are two consequences including detection of any alteration to the message due to the digest message algorithm and the individual cannot repudiate signing the message since, he did it with his private key. These features, message integrity as well as non-repudiation help to make digital signature a very beneficial component for use in those aspects of world and life where security is highly required.

This is the reason; many confidential and governmental establishments prepare their private and important documents by making use of the digital signature, which guarantees security.

Suppose an individual wants to send to his lawyer, the draft of a contract through e-mail and give the assurance to his lawyer that it is really from him and is unchanged from what he has sent then he can do so by making use of digital signature. To do this, the individual should copy and paste the contract into an e-mail note. Then by using special software, the individual should obtain a message hash, which is a mathematical summary of the contract.

Thereafter, the individual should use a private key, which he has previously acquired from a private-public key authority to encode the hash. This encrypted hash becomes the individual’s digital signature of the message. It is important to keep in mind; the encrypted hash will be different each time the individual sends a message by making use of digitalsignature.

At the other end, the individual’s lawyer receives the message. In order to ensure that the message is intact and from the individual, the lawyer makes a hash of the message he has received.

Next, the lawyer uses the individual’s public key to decode, the message summary or hash. The message received is valid if the hashes match. This goes to show, there are numerous benefits of digital signature and therefore an individual should make use of it whenever he wants to maintain security, integrity, and non-repudiation of his message.