The legal foundation: IT Act 2000

India's Information Technology Act 2000 (IT Act) establishes the legal framework for electronic signatures. Under Section 5, a digital signature or electronic signature is legally valid if it satisfies the conditions set out in the Second Schedule. An Aadhaar-based eSign — where the signer authenticates via OTP sent to their Aadhaar-registered mobile — satisfies these conditions and is therefore court-admissible.

The Controller of Certifying Authorities (CCA) under the Ministry of Electronics and IT (MeitY) regulates eSign service providers. Only CCA-licensed eSign providers can issue legally valid Aadhaar-based eSignatures. When you use an eSign API, ensure the underlying provider is CCA-licensed.

How Aadhaar OTP eSign works

The process has four steps:

  1. Document preparation: The document to be signed is hashed and a signing request is prepared.
  2. Aadhaar OTP: The signer enters their Aadhaar number. UIDAI sends an OTP to their registered mobile. The signer enters the OTP to authenticate.
  3. Signature generation: The CCA-licensed eSign provider generates a digital signature using the signer's identity as confirmed by UIDAI. The signature is embedded in the document.
  4. Audit trail: A tamper-proof audit record is created containing the signer's identity hash, OTP timestamp, document hash, and signing timestamp.

The entire process takes 10–20 seconds for the signer. The resulting signed document is a standard PDF with an embedded digital signature that can be verified by any PDF reader or court.

What makes it court-admissible?

For an Aadhaar-based eSign to be court-admissible in India, it must meet the following requirements:

  • CCA-licensed provider: The eSign must be generated by a provider licensed by the Controller of Certifying Authorities. A custom OTP-plus-hash solution does not qualify.
  • UIDAI authentication: The signer's identity must be confirmed via UIDAI's Aadhaar OTP infrastructure — not a third-party OTP or email link.
  • Audit trail integrity: The audit trail must be tamper-proof. A simple database log is insufficient; the audit record must be cryptographically linked to the signed document.
  • Document integrity: The document must be unchanged after signing. Any modification invalidates the signature. Use PDF/A format for archival documents.

Veriflow note: The Veriflow esign module uses a CCA-licensed eSign provider. UIDAI OTP authentication, audit trail generation and PDF embedding are handled by the API. Your integration only needs to pass the document and the signer's Aadhaar number.

Where eStamp fits in

eSign and eStamp solve different problems. eSign proves who signed a document. eStamp (electronic stamping) replaces physical stamp paper for agreements that attract stamp duty under the Indian Stamp Act.

For most loan agreements, vendor contracts, and employment agreements above ₹500 in value, stamp duty is required. An unstamped agreement can be admitted in court but attracts penalty and duty before it can be used as evidence. eStamp is available in most states and can be procured digitally before or at the time of signing.

The practical workflow: generate eStamp → embed stamp certificate in document → trigger eSign via Aadhaar OTP → deliver signed and stamped PDF to both parties. Veriflow's esign module handles eStamp integration where the state's eStamp authority supports API access.

Common mistakes to avoid

  • Using email OTP instead of Aadhaar OTP: An email link or SMS OTP from your own system does not create an IT Act-compliant digital signature. It may be useful for acknowledgment but is not court-admissible as a signature.
  • Not storing the audit trail: The signed PDF alone is not sufficient. The audit trail — signer identity, OTP timestamp, document hash — must be stored separately and linked to the document for 7+ years.
  • Signing a mutable document: If any field in the document can be changed after signing (e.g. a fillable PDF form with unfilled fields), the signature may be invalidated by the modification. Flatten the PDF before signing.
  • Skipping eStamp for dutiable agreements: A signed-but-unstamped agreement for a loan or property deal can be challenged on admissibility. Get the stamp before you circulate for signature.