Digital Signature and eSign Explained | JKSSB Mock Test
Digital Signature and eSign
Digital signature and eSign are methods to sign electronic documents that provide authentication, integrity and non-repudiation. While both replace handwritten signatures in many contexts, they are based on different technical and procedural models. Understanding both is useful for aspirants of UPSC, SSC and JKSSB, professionals working with e-governance, law, finance, and anyone dealing with digital contracts or identity verification.
Concise definitions
A digital signature is a cryptographic construct that binds a signer’s identity to the contents of a digital document using asymmetric keys and certificates. An eSign (electronic signature) is a broader term for any electronic method that indicates acceptance of an electronic document — it may be as simple as a scanned image of a signature, a typed name, or a more secure certificate-based signature.
Key differences at a glance
- Nature: Digital signatures use public-key cryptography (PKI). eSign is an umbrella term for electronic signing methods.
- Security: Digital signatures provide strong integrity and non-repudiation; basic eSigns may be weaker unless backed by verification.
- Legal weight: Many laws recognise both, but digitally signed documents using certificates often enjoy stronger evidentiary value.
- Typical use: Digital signatures for contracts, tax filings, and notarised documents; eSign for low-risk approvals and user consent flows.
How a digital signature works — simplified
Digital signatures rely on asymmetric cryptography, certificates and trusted authorities. The high-level workflow is:
- Key pair generation: The signer generates a private key (kept secret) and a public key (shared).
- Hashing: The document is hashed using a cryptographic hash function to create a fixed-size digest.
- Signing: The signer encrypts (signs) the digest with their private key. This signed digest is the digital signature.
- Certificate: A Certificate Authority (CA) issues a digital certificate that links the public key to the signer’s identity.
- Verification: The verifier obtains the signer’s public key (from the certificate), decrypts the signature to get the digest, recomputes the document’s hash, and compares — if they match and the certificate is valid, signature verification succeeds.
What is eSign (electronic signature)?
eSign refers to any electronic method that indicates acceptance or approval of an electronic record. This includes:
- Scanned images of handwritten signatures embedded in PDFs.
- Tick-boxes, typed names or “I accept” buttons in web forms.
- Cloud-based signature services that capture user intent and authentication (OTP, biometric, Aadhaar-based eSign etc.).
- Certificate-backed digital signatures (when integrated with PKI, these are also eSigns but with stronger guarantees).
Components of a secure digital signing system
- Public Key Infrastructure (PKI): Keys, certificates, CAs and revocation mechanisms.
- Certificate Authority (CA): Trusted entity that issues and manages digital certificates.
- Time-stamping: Ensures signature time is recorded and can be trusted later.
- Revocation list / OCSP: Allows checking whether a certificate was revoked at verification time.
- Audit trail: Logs of signing events, IPs, user authentication used for legal evidence.
Common use-cases
- Government forms and e-governance services
- Income tax, GST, and regulatory filings
- Banking and loan documents
- Commercial contracts, NDAs, and purchase orders
- Software distribution and code signing
- Health records and medical consent forms
Practical step-by-step eSign workflows (typical scenarios)
- User-initiated eSign (simple): User uploads a document to a signing portal → authenticates (username/password or OTP) → places a signature (typed or drawn) → server stores stamped document and audit trail.
- Certificate-based digital signature: Document is prepared → signer uses a private key (hardware token/ HSM / keystore) to sign → CA-issued certificate attached → signed document distributed with verification instructions.
- Remote or Aadhaar-based eSign (country-specific): User authenticates via a government-backed identity method → OTP/biometric used to confirm intent → an authorised eSign service issues a signature token and signs the document on behalf of the user.
Legal and policy perspective (brief)
Many jurisdictions legally recognise electronic signatures and provide rules for admissibility in court. Typically, laws differentiate between simple eSigns (acceptable for low-risk contexts) and advanced/certificate-based digital signatures (given stronger legal presumption of authenticity). In practice, the evidentiary strength depends on how well the signing process preserves identity, intent, integrity and auditability.
Security risks and mitigations
- Risks: Private key compromise, certificate forgery, replay attacks, weak authentication for eSign portals.
- Mitigations: Use hardware security modules (HSMs) or secure tokens for private keys; multi-factor authentication (MFA); timestamping services; maintain certificate revocation checks; keep an immutable audit trail.
How to verify a signed document — quick checklist
| Step | What to check |
|---|---|
| 1 | Signature cryptographic validity (signature matches document hash). |
| 2 | Certificate validity (issued by trusted CA, not expired or revoked). |
| 3 | Timestamp integrity (signature time is recorded and trusted). |
| 4 | Audit trail (who signed, how they authenticated, IP / device if required). |
Common misconceptions
- “Scan and paste is as secure as a digital signature.” — A scanned signature image offers little cryptographic assurance; it’s easy to copy and tamper with.
- “All eSignatures are legally equal.” — Legal weight varies by jurisdiction and the strength of the signing process.
- “Digital signatures are unbreakable forever.” — Cryptography evolves; key lengths, algorithms and certificate management must be maintained.
Exam-relevant one-liners (memorise these)
- Digital signature = cryptographic mechanism using private/public keys to ensure document integrity and signer authenticity.
- eSign = any electronic method to indicate acceptance; may be simple or certificate-backed.
- PKI provides the trust infrastructure (keys, certificates, CAs) for secure digital signatures.
- Time-stamping preserves the signing time and strengthens evidence in disputes.
Conclusion
Digital signatures and eSigns are fundamental to modern digital transactions, enabling trust, efficiency and legal compliance in electronic workflows. For low-risk interactions, basic eSigns may suffice; for high-value contracts, certificate-backed digital signatures with robust PKI, time-stamping and audit trails are recommended. For students and exam aspirants, focus on definitions, the PKI model, how signing and verification work, and the practical differences between simple eSign methods and cryptographic digital signatures.
FAQs
Q1: Is a scanned signature legally valid?
A scanned image can indicate intent in some contexts, but it lacks cryptographic integrity and is weaker evidence compared to certificate-based digital signatures. Admissibility depends on jurisdiction and the circumstances.
Q2: Can a digital signature be forged?
Not practically, if strong cryptographic algorithms and secure private key storage are used. However, weak keys, poor key management, or compromised devices can enable forgery.
Q3: What happens if a private key is lost?
If the private key is irrecoverably lost, signatures cannot be produced with that key; certificates should be revoked to prevent misuse. Recovery policies vary and may involve re-issuing certificates after identity re-validation.
Q4: Are digital signatures the same as encryption?
No. Digital signatures provide authentication and integrity (they prove who signed and that the document wasn't changed). Encryption protects confidentiality (keeps the document secret). The two are complementary and often used together.
Q5: How often should certificates be renewed?
Certificate validity periods vary; shorter lifetimes (1–3 years) are common practice to reduce risk. Renew certificates before expiry and immediately revoke them if compromise is suspected.
