UPSC Prelims 2019 Q94: Science & Technology – Computer & Information Technology
- (a) 1 only
- (b) 2 and 3 only
- (c) 3 only
- (d) 1, 2 and 3
Answer: (c) 3 only
Explanation
Digital Signature: What It Is
| Statement | Claim | Verdict | Detail |
|---|---|---|---|
| 1 | Electronic record that identifies certifying authority | FALSE | The digital signature itself does NOT identify the CA; it is the digital signature CERTIFICATE (issued by CA) that identifies the CA. The signature is a cryptographic value. |
| 2 | Serves as proof of identity to access information/server | FALSE | A digital signature does not directly serve as identity proof for access; it authenticates a specific document/transaction. Identity proof mechanisms are separate (biometric, OTP, KYC). |
| 3 | Electronic method of signing an electronic document + ensures original content is unchanged | TRUE | Digital signatures use asymmetric cryptography (hash + private key) to prove authenticity + integrity. Any change in the document invalidates the signature. |
Only statement 3 is correct. Answer: (c) 3 only.
Answer: (c) 3 only.
Why each option is right or wrong
- (a) Incorrect. Statement 1 confuses digital signature with digital certificate.
- (b) Incorrect. Statement 2 conflates document authentication with identity/access proof.
- (c) CORRECT. Only statement 3 is right - digital signature is an electronic signing method that provides both authentication and integrity (content unchanged).
- (d) Incorrect. Statements 1 and 2 are wrong.
Key point
Digital signature = cryptographic sign providing authentication + integrity (content unchanged). Digital signature CERTIFICATE (DSC) = issued by CA and identifies the CA + signer. Legal basis: IT Act 2000.
Remember
Only statement 3 is correct. A digital signature is an electronic method of signing an electronic document and ensures that the original content is unchanged (authentication + integrity). It is NOT itself an identifier of the certifying authority (that's the digital signature certificate) and does NOT directly serve as identity proof for accessing servers.
Common mistakes
- Confusing digital signature (cryptographic value) with digital signature certificate (identity credential).
- Assuming digital signature = identity proof - it is document-authentication proof.
- Not knowing IT Act 2000 gives digital signatures legal equivalence to handwritten signatures.
Exam tip
Digital signature workflow: (i) Compute hash of document. (ii) Encrypt hash with signer's private key = digital signature. (iii) Recipient decrypts with signer's public key -> verifies hash matches. (iv) Any change in document breaks the signature. Provides authentication + integrity + non-repudiation.
Sources
- IT Act, 2000 and IT Rules - Digital signature provisions
- Controller of Certifying Authorities (CCA), India - DSC framework