> 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/product-portfolio-and-selection-guide.md).

# Product Portfolio and Selection Guide

Use this guide to pick the right signing service for your use case.

## Decision guide

| If you need to…                                                                                        | Use                                   |
| ------------------------------------------------------------------------------------------------------ | ------------------------------------- |
| Let any Aadhaar holder sign a form once, with no registration                                          | **eSign v2**                          |
| Use biometric (fingerprint/iris) or face authentication for higher assurance or assisted channels      | **eSign v2** with AuthMode 2, 3 or 4  |
| Let users without an Aadhaar-linked mobile, NRIs, foreign nationals or organisational signatories sign | **eSign v3**                          |
| Sign up to 5 documents in one transaction, asynchronously                                              | **eSign v3**                          |
| Let a frequent signer sign many times with a long-term certificate, without a USB token                | **Remote Key Storage**                |
| Sign up to 10 documents in one authorisation with a long-term key                                      | **Remote Key Storage**                |
| Sign system-generated documents automatically with the organisation's signature                        | **Remote Signing (Document Signer)**  |
| Verify signatures on documents you receive                                                             | **Digital Signature Validation Tool** |

## Comparison

|                       | eSign v2                                | eSign v3                                        | Remote Key Storage                             | Remote Signing                             |
| --------------------- | --------------------------------------- | ----------------------------------------------- | ---------------------------------------------- | ------------------------------------------ |
| CCA specification     | eSign API 2.1                           | eSign API 3.3                                   | eSign Remote API 1.1                           | — (organisational DSC)                     |
| Signer                | Individual (Aadhaar)                    | Individual / organisational person              | Individual                                     | Organisation / system                      |
| Enrolment             | None                                    | One-time eKYC account                           | eKYC account + key enrolment                   | Certificate issuance at onboarding         |
| Authentication        | OTP, fingerprint, iris, face            | PIN + SMS-OTP / TOTP / MAT / FIDO2 / public-key | AuthPIN (verified in HSM) + ASP authentication | API credentials + IP allow-list / mTLS     |
| Certificate validity  | ≤ 30 minutes                            | ≤ 30 minutes                                    | Long-term (default 2 years)                    | 1–3 years                                  |
| Key handling          | Generated and destroyed per transaction | Generated and destroyed per transaction         | Stored HSM-wrapped                             | Stored in HSM                              |
| Documents per request | 1                                       | Up to 5                                         | Up to 10                                       | Up to 10 hashes per call; unlimited volume |
| Interaction           | Synchronous redirect                    | Asynchronous (callback + status API)            | Asynchronous (callback + status API)           | Synchronous API                            |
| Algorithms            | RSA / ECDSA                             | RSA or ECDSA (`signingAlgorithm`)               | Default ECC P-256 / SHA-256                    | RSA / ECC                                  |

## Access options

* **Direct ASP integration** — register as an ASP with eMudhra and call the APIs directly.
* **emSigner gateway** — use eMudhra's emSigner workflow platform, which is pre-integrated with eSign, to sign without registering as an ASP.
* **Integration kits and SDKs** — ready-to-use kits for Java, .NET and mobile (Android/iOS) that handle hashing, XML signing and signature embedding.