Fundamentals of Business Laws and Business Communication · E-Contracts and E-Signature - Meanings and Requirements

Electronic Signature and Digital Signature under the IT Act

Updated 10 October 2026 · Fact-checked

An electronic signature is any method of authenticating an electronic record through a technique listed in the Second Schedule of the IT Act, 2000. A digital signature is one such technique, made using asymmetric cryptography and a hash. So every digital signature is an electronic signature, but not the reverse.

Understand Electronic Signature and Digital Signature

A signature proves two things: who signed, and that the signer accepts the document. When documents moved online, the law needed a way to give the same effect to online signing. The Information Technology Act, 2000 (IT Act) does this through two ideas: electronic signature and digital signature.

The IT Act defines electronic signature as authentication of an electronic record by a subscriber using a technique specified in the Second Schedule. It includes a digital signature. The definition is technology neutral. Any technique can qualify if it is listed in the Schedule and is reliable. Examples are Aadhaar eKYC-based e-sign and, in the original Act, the digital signature method.

A digital signature is created with asymmetric cryptography, also called public key cryptography. The signer has two linked keys. The private key is kept secret and is used to sign. The public key is shared and is used to verify. The two keys form a pair.

Here is how it works. The software first runs the document through a hash function, which produces a short fixed-size value called a hash or message digest. The signer's private key then encrypts this hash. The result is the digital signature, which travels with the document. The receiver uses the signer's public key to decrypt the signature and gets the hash. The receiver also hashes the received document. If both hashes match, the document is unchanged and was signed by the holder of that private key.

This gives three things: authentication (who signed), integrity (no change after signing) and non-repudiation (the signer cannot easily deny signing). The link between a person and a public key is certified by a Digital Signature Certificate, issued by a Certifying Authority licensed under the Act.

Key formulas to remember

Electronic signature: Electronic signature = authentication of an electronic record by a subscriber using a technique in the Second Schedule of the IT Act, 2000; It is a wider term. It includes digital signature.
Digital signature: Digital signature = hash of the record encrypted with the signer's private key; verified with the public key; It uses asymmetric cryptography (a key pair) and a hash function.
Relationship: Digital signature ⊂ Electronic signature; Digital signature is a type (subset) of electronic signature.
Key roles: Private key signs ; Public key verifies; The private key is secret. The public key is open to all.
Three features: Authentication + Integrity + Non-repudiation; These are what a valid digital signature gives.
Legal effect: Where law requires a signature, an electronic signature meeting the Act's conditions satisfies that requirement; This is what makes electronic signing legally valid.

How to solve Electronic Signature and Digital Signature questions

Most questions test a definition, a link between the two terms, or a feature. Use this method.

1Read the question and mark the key word: electronic signature, digital signature, private key, public key, hash or certificate.
2Decide the level: is it asking about the wider concept (electronic signature) or the specific technique (digital signature)?
3Recall the definition. Electronic signature: authentication by a Second Schedule technique. Digital signature: asymmetric cryptography and hash.
4For a process question, follow the order: hash the document, encrypt the hash with the private key, verify with the public key.
5For a difference question, compare on technology, scope, security and certificate.
6Eliminate options that swap the keys, call digital signature the wider term, or say a signature needs paper.
7Pick the option that matches the Act's wording and check no word contradicts it.

Quickest way: Three-line recall

When to use it: Use when you have about a minute for an MCQ on meaning, keys or difference.

Electronic signature is the whole family. Digital signature is one member.
Sign with the private key. Verify with the public key.
Digital signature gives authentication, integrity and non-repudiation, and needs a certificate from a Certifying Authority.

Common mistakes in Electronic Signature and Digital Signature

Saying electronic and digital signatures are the same thing.
Both words sound alike and are used loosely in daily life.
Fix: Remember digital is a type of electronic. Electronic is the wider term.
Saying the public key is used to sign.
Students confuse this with encryption of messages for secrecy.
Fix: For signing, the private key signs and the public key verifies.
Thinking a digital signature is a scanned image of a handwritten signature.
The word signature suggests a picture of one's name.
Fix: A digital signature is a cryptographic value tied to the document and the key. A scanned image is not one.
Forgetting the role of the hash.
Students focus only on keys.
Fix: The hash is what proves integrity. If the document changes, the hash no longer matches.
Ignoring the Certifying Authority.
The certificate step is skipped in simple explanations.
Fix: The Digital Signature Certificate links the public key to a named person and is issued by a licensed Certifying Authority.

Worked examples

Example 1

Which of the following is correct about electronic signature and digital signature under the IT Act, 2000?
(a) Electronic signature is a type of digital signature
(b) Digital signature is a type of electronic signature
(c) They are unrelated
(d) Digital signature does not need any key

Show the solution

Electronic signature is defined by reference to techniques in the Second Schedule.
Digital signature, made with asymmetric cryptography, is one such technique.
So digital signature falls inside electronic signature, not the other way round.
Option (a) reverses the relation. Option (c) is wrong. Option (d) is wrong as keys are essential.

Answer: (b) Digital signature is a type of electronic signature.

Example 2

Ravi sends a signed contract to Meera using a digital signature. Which key does Meera use to verify the signature, and what does a match show?
(a) Ravi's private key; the document is secret
(b) Meera's private key; Ravi is rich
(c) Ravi's public key; the document is unchanged and signed by Ravi's key holder
(d) Meera's public key; the document is unchanged

Show the solution

Signing uses the signer's private key, so Ravi signed with his private key.
Verification uses the signer's public key, which is Ravi's public key.
Meera decrypts the signature to get a hash and hashes the received document herself.
If the two hashes match, the document was not altered and came from the holder of Ravi's private key.
Options (a), (b) and (d) name the wrong key or the wrong result.

Answer: (c) Ravi's public key; the document is unchanged and signed by Ravi's key holder.

Exam tips

Expect direct definition MCQs. Learn the wording: authentication of an electronic record using a Second Schedule technique.
Learn the direction of the relationship. Many options reverse it.
Remember private key signs and public key verifies. This is a favourite trap.
For difference questions, think technology, scope and certificate: digital signature is specific, uses a key pair and a certificate; electronic signature is wider and technology neutral.

Practice questions from E-Contracts and E-Signature - Meanings and Requirements

Electronic Signature and Digital Signature in other exams

The same ground in other exams, if you are preparing for more than one or want another angle on it.

Electronic Signature and Digital Signature: frequently asked questions

What is an electronic signature under the IT Act, 2000?

It is the authentication of an electronic record by a subscriber using a technique specified in the Second Schedule of the Act. It includes a digital signature. It gives legal effect to signing online.

What is the difference between digital signature and electronic signature?

Electronic signature is the wider term and can use any technique listed in the Schedule. Digital signature is a specific technique based on asymmetric cryptography and a hash, supported by a certificate. So every digital signature is an electronic signature, but not every electronic signature is a digital signature.

How does a digital signature work?

The software hashes the document and encrypts the hash with the signer's private key. The receiver decrypts it with the public key and compares it with a fresh hash of the document. A match shows the document is unchanged and was signed by the key holder.

Why is a Certifying Authority needed?

A public key alone does not say who owns it. A licensed Certifying Authority issues a certificate that links the public key to a named person. This lets others trust the signature.