A digital signature is a mathematical technique which validates the authenticity and integrity of a message, software or digital documents. It allows us to verify the author name, date and time of signatures and authenticate the message contents. The digital signature offers far more inherent security and intended to solve the problem of tampering and impersonation in digital communications.

Application of Digital Signature

·         Authentication

·         Non-repudiation

·         Integrity


Authentication is a process which verifies the identity of a user who wants to access the system. In the digital signature, authentication helps to authenticate the sources of messages.


Non-repudiation means assurance of something that cannot be denied. It ensures that someone to a contract or communication cannot later deny the authenticity of their signature on a document or in a file or the sending of a message that they originated.


Integrity ensures that the message is real, accurate and safeguards from unauthorized user modification during the transmission.

The steps which are followed in creating a digital signature are:

·         Select a file to be digitally signed.

·         The hash value of the message or file content is calculated. This message or file

      content is encrypted by using a private key of a sender to form the digital signature.

·         Now, the original message or file content along with the digital signature is


·         The receiver decrypts the digital signature by using a public key of a sender.

·         The receiver now has the message or file content and can compute it.

·         Comparing these computed message or file content with the original computed          message. The comparison needs to be the same for ensuring integrity.

Types of Digital Signature

·         Certified Signatures

·         Approval Signatures

·         Visible Digital Signature

·         Invisible Digital Signature

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