Detailed Explanation:

Answer: Option 3 — 3 only

A digital signature is a cryptographic mechanism used to authenticate the identity of the sender and ensure that the content of an electronic document has not been altered after signing. Only statement 3 correctly captures this fundamental purpose.

❌ Statement 1 – Incorrect: A digital signature does not identify the certifying authority; instead, it uses a digital certificate issued by a Certificate Authority (CA) to verify the signer's identity, but the signature itself is created by the signer's private key.

❌ Statement 2 – Incorrect: Digital signatures are primarily used for ensuring document integrity and authenticity, not for accessing information or servers on the Internet; access control typically relies on usernames, passwords, tokens, or biometric authentication.

✅ Statement 3 – Correct: A digital signature is indeed an electronic method of signing documents that ensures non-repudiation and integrity by creating a unique cryptographic hash that detects any changes to the original content.

📝 Short Notes: Digital Signatures

• Definition: A digital signature is a cryptographic technique that validates the authenticity and integrity of electronic messages, documents, or software.
• Technology: Based on Public Key Infrastructure (PKI) using asymmetric cryptography—a private key to sign and a public key to verify.
• Key Functions: Authentication (verifies sender identity), Integrity (detects alterations), and Non-repudiation (sender cannot deny signing).
• Process: A hash of the document is created and encrypted with the signer's private key; recipients decrypt it with the public key to verify authenticity.
• Legal Status in India: Digital signatures are legally recognized under the Information Technology Act, 2000, and have the same validity as handwritten signatures.
• Certificate Authority (CA): Trusted third parties (like NIC, eMudhra) issue digital certificates that bind a public key to an individual or organization.
• Common Uses: E-filing of tax returns, online banking, e-governance services, legal documents, and software distribution.