> ## Documentation Index
> Fetch the complete documentation index at: https://docs.ulm.m1amdocs.com/llms.txt
> Use this file to discover all available pages before exploring further.

# One-Time Password Authentication

Digital Identity Management supports authentication using One-Time passwords (OTP) that are sent to the user by email or SMS. This flow can be implemented for a user that may or may not have a password.

Leverage OTP authentication by sending the user one of Digital Identity Management's supplied notification templates from the [Admin console](https://docs.vindicia.com/bundle/b_connectAdminGuide/page/topics/branding_c.html). Notifications sent to the user's preferred notification channel can be email or SMS. The relevant templates are as follows:

* Email - **general-verification-of-authentication-identifier-with-otp\_header.html** and **general-verification-of-authentication-identifier-with-otp\_header.txt**
* SMS - **general-verification-of-authentication-identifier-with-otp\_header.txt**

## Authenticate With OTP

Digital Identity Management supports authentication with a One-Time Password (OTP) even if the user has a password. The following scenario outlines the general flow for OTP authentication:

1. The user navigates to the organization’s login page.
2. The user enters an email address or mobile number and password (if required).
3. The user receives a notification (email/SMS) with an OTP, that they can now enter on the UI.
4. The user is authenticated and redirected to the destination URL completing their login process.

OTPs can only be used once for authentication, and previously issued OTPs are invalidated. The expiry time for the OTP is controlled by the **Short token expiration period** setting that's configured from the **Admin console**.

**Benefits of OTP Authentication**

OTP is useful for a user who forgets their password and doesn't want to reset it or a user doesn't want to enter a long complex password. The OTP is an streamlined method for users to sign in and access resources.

## Related topics

The following topics provide more details and use cases for OTP authentication:

* [Authenticate user AuthN ID and OTP (no password)](https://docs.vindicia.com/bundle/b_processGuide/page/topics/useCaseAuthV2EmailMobileOtpNoPw_c.html)
* [Authenticate user with AuthN ID and OTP/Magic Link](https://docs.vindicia.com/bundle/b_processGuide/page/topics/useCaseAuthV2EmailMobileOtpLinkPwLess_c.html)
* [Action Tokens - Proof Key for Action Tokens (PKATs)](https://docs.vindicia.com/bundle/b_processGuide/page/topics/c_actionTokens.html#section_irr_wss_cpb)
* [Identity App OTP Reporting Errors](otpIdentityAppErrorReporting_r)
* [Onboarding and Authentication Errors](https://docs.vindicia.com/bundle/b_processGuide/page/topics/onboardAuthV2Errors_c.html)

**Parent topic:**[User Onboarding and Authentication](../topics/userOnboardingAndAuthentication)


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