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Zoho Sign

Signer Authentication (Sign)

Signer Authentication in Zoho Sign is a verification step that confirms a recipient's identity before they can access or sign a document, using methods

Technical Term

Signer authentication is the gate before the signature field: it proves that the person opening the signing link is the intended recipient, not someone who merely forwarded the email. The authentication event itself is logged in the audit trail, adding an extra layer of non-repudiation evidence beyond the electronic signature alone.

How Signer Authentication Works in Zoho Sign

When configuring a document or template, the sender selects an authentication method for each recipient role. Options available in Zoho Sign include email-based OTP (a one-time code sent to the recipient’s email), SMS OTP (sent to a mobile number), access code (a shared password the sender communicates separately), and Aadhaar eSign (biometric or OTP-based identity verification using India’s national ID infrastructure). The recipient must complete the chosen challenge before the document opens for signing.

When to Use Signer Authentication

Apply signer authentication whenever the document carries legal, financial, or regulatory weight and the cost of an impostor signing is high: employment contracts, loan agreements, non-disclosure agreements, or regulated consent forms. SMS OTP or Aadhaar eSign is appropriate for Indian counterparties where mobile numbers are reliable identifiers. Email OTP is simpler but provides weaker assurance since email accounts can be shared or compromised.

Key Considerations for Signer Authentication

SMS OTP delivery depends on the recipient’s mobile number being entered correctly and having network coverage; failed delivery blocks signing until the sender resends or switches method. Aadhaar eSign incurs per-transaction charges from the Authentication Service Agency and requires the signer to have a registered Aadhaar number. Access codes must be shared through a separate, secure channel; do not include them in the same signing-invitation email. Each authentication method adds friction, so calibrate the level to the document’s actual risk.

India Example: A Mumbai non-banking financial company sends loan sanction letters via Zoho Sign with Aadhaar eSign authentication. Each borrower verifies their identity using their Aadhaar number and OTP before signing, satisfying the company’s KYC obligations and creating a court-admissible identity record alongside the signature.
Can different recipients in the same document use different authentication methods?

Yes. Zoho Sign lets you configure authentication per recipient role, so one signatory can be required to complete an SMS OTP while another uses an access code or Aadhaar eSign. This lets you apply stronger verification to higher-risk signers (such as the borrower) while keeping friction lower for internal approvers.

Is signer authentication the same as a digital signature certificate?

No. Signer authentication verifies identity at the moment of document access; a digital signature certificate (DSC) is a cryptographic credential issued by a licensed authority that is embedded into the document. They serve complementary purposes: authentication proves who opened the document, while a DSC cryptographically binds the signer’s identity to the signed content.

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