> For the complete documentation index, see [llms.txt](https://docs.emudhradigital.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.emudhradigital.com/documentation/esign-v3-ca-ekyc-account/esign-v3-overview.md).

# eSign v3 Overview

**eSign v3** implements CCA *eSign API Specification 3.3 — CA eKYC Account based*. Instead of authenticating online against UIDAI on every transaction, the signer holds a one-time-registered **eKYC account** with eMudhra (the CA). At signing time the signer authenticates to that account with a **PIN plus a second factor**, and eMudhra issues a one-time DSC from the verified account data.

## At a glance

| Attribute             | Value                                                                                                                                                                                            |
| --------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| Specification         | eSign API 3.3 (3.0 – 3.3 released Dec 2018 – Dec 2020)                                                                                                                                           |
| Identity source       | CA eKYC account — offline Aadhaar XML, PAN, bank eKYC, organisational KYC, foreign nationals (see [KYC Types and Acceptable Documents](broken://pages/68267c3444049c11fb237079aa88a5f4d339ac16)) |
| Authentication        | PIN + SMS-OTP / TOTP / Mobile Access Token / FIDO2 / public-key signature                                                                                                                        |
| Certificate           | eKYC class, one-time, ≤ 30 minutes                                                                                                                                                               |
| Documents per request | Up to 5                                                                                                                                                                                          |
| Algorithms            | `RSA` or `ECDSA` (selected per request)                                                                                                                                                          |
| Signature types       | `raw`, `PKCS7`, `PKCS7pdf`, `PKCS7complete`                                                                                                                                                      |
| Interaction           | Asynchronous — acknowledgement (status 2), callback to `responseUrl`, status-check API                                                                                                           |
| Wait period           | `maxWaitPeriod` in minutes (default 1440)                                                                                                                                                        |

## Differences from eSign v2

|                       | eSign v2                       | eSign v3                                                                                      |
| --------------------- | ------------------------------ | --------------------------------------------------------------------------------------------- |
| Identity              | Online Aadhaar per transaction | Pre-registered CA eKYC account                                                                |
| Registration          | None                           | One-time (approved typically within \~30 minutes)                                             |
| Who can sign          | Aadhaar holders                | Aadhaar (offline), PAN holders, bank customers, organisational signatories, foreign nationals |
| Authentication        | Aadhaar OTP / biometric / face | PIN + second factor                                                                           |
| Documents             | 1                              | Up to 5                                                                                       |
| Flow                  | Synchronous redirect           | Asynchronous with callback and status API                                                     |
| Signer identification | `ekycId`                       | `signerid` (`id@id-type.esp-id`)                                                              |
| Algorithm choice      | Fixed by ESP                   | `signingAlgorithm` = `RSA` / `ECDSA`                                                          |
| Document link         | —                              | `docUrl` shown to signer                                                                      |

## When to choose eSign v3

* Signers whose mobile is not linked to Aadhaar, or who prefer not to use Aadhaar online.
* Signing on behalf of an organisation (organisational person certificates).
* NRIs and foreign nationals.
* Batches of up to 5 documents in one authorisation, or flows where the signer approves later (e.g., in the eMudhra mobile app).