Digital Signature

A digital signature is like a real signature that is used to validate the authenticity and integrity of a message or software or any digital document or financial transaction. It symbolizes that the element is solely originated by the signer and also protects the elements from forgery or tampering. This post is a part of our Free and Complete Computer Notes important for most of the competitive Exams as UPSC CSE, State PCS, SSC CGL, CHSL, MTS, FSSAI, ASRB, Railways, DMRC, CDS, NDA, and others. You can also check out Our Courses.

What is Digital Signature?

A Digital Signature is an electronic, encrypted, stamp of authentication on digital information such as email messages, macros, or electronic documents. A signature confirms that the information originated from the signer and has not been altered.


The following terms and definitions show what assurances are provided by digital signatures:


The signer is confirmed as the signer. It verifies the identity of a user who wants to access the system.


The content has not been changed or tampered with since it was digitally signed. It ensures that the message is real, accurate and safeguards from unauthorized user modification during the transmission.


Proves to all parties the origin of the signed content. Repudiation refers to the act of a signer denying any association with the signed content.

What are the types of Digital signatures?

There are three types of digital signatures.

  1. The first type of Digital Signature provides a basic level of security and are used in such area where there is a low risk of data compromise. This type of digital signature does not use for legal business. Example – Social Media log-in credential (user id and password); email user id and password etc.
  2. The second type of Digital Signature are used where data compromisation risks are moderate. Electronic filling of tax documents, income tax returns files and GST returns files are few examples.
  3. The third type of Digital Signature are used where data risks are very high. It is used for e-auctions, e-tendering, e-ticketing, court fillings etc. It requires a person or organisations to present in front of a certifying authority to provide their identity before signing. Example – Aadhar, Banking, Patent & Trade mark etc.

Benefits of Digital Signatures

  1. Digital security
  2. Legal authentication
  3. Global Acceptance
  4. Time & Cost saving for hand copies of signature of documents
  5. Trace ability

Signing Certificate

To create a digital signature, you need a signing certificate, which proves identity when you send a digitally signed macro or document, you also send your certificate and public key.

Certificates are issued by a certification authority, a certificate is usually valid for a year, after which, the signer must renew or get a new, signing certificate to establish identity.

Validation of Digital Signature

To make a digital signature valid –

  • The associated signing certificate must be current.
  • The signing person or organization or the publisher must be trusted.

Methods of Digital Signature

Personal identification number (PIN), Password & Codes

It is required for the authentication and verification of the signer’s identity. Email, User id and password are its types.

Asymmetric Cryptographic

Based on a public key algorithm and includes private and public-key encryption and authentication. Software Product key, the License Product key is its example.


These are the tools with which we can check the difference between original and forgery files. It is basically a type of error detection method.

It is a long string of letters and numbers that represents the sum of the correct digits in a piece of digital data, against which comparisons can be made to detect errors or changes. A checksum acts as a data fingerprint.

CRC (Cyclic redundancy Check)

It is also an error detecting method used in digital networks and storage devices to detect changes to raw data.

Certificate Authority (CA) Validation

Certificate authorities issue digital signatures and act as trusted third parties by accepting, authenticating, issuing, and maintaining digital certificates. The use of Cas helps avoid the creation of fake digital certificates.

Trust Service Provider (TSP) Validation

A TSP is a person or legal entity that performs validation of a digital signature on a company’s behalf and offers signature validation reports.


How many algorithms digital signature consists of?

a digital signature consists of three algorithms – key generation algorithm, signing algorithm and signature verifying algorithm.

which algorithm provides the private key and its corresponding public key?

Key generation algorithm
The key generation algorithm selects a private key randomly from a set of possible private keys. This algorithm provides the private key and its corresponding public key.

Authentication in Digital signature means ___?

in Digital signature, authentication means the Verification of the user’s identification and verification of the data.

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