> **Source:** https://knowledge.leegality.com/document-execution/leegality-features/invitee-level/security/one-factor-authentication
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# One Factor Authentication

**One Factor Authentication** adds an essential layer of security to the signing process by requiring invitees to authenticate their identity via OTP sent to their Email ID or Phone Number (as configured during document setup). This ensures that only the intended recipient can access and view the document, safeguarding against unauthorized access due to mistaken forwarding of signing invitations.

## Use One Factor Authentication

> **Info — Note**
>
> One Factor Authentication does not work with Quick Sign.

## Signing Journey

1. Click the **Sign** button in the email invitation or the eSign link received via SMS.  
2. Provide the OTP sent to the email address or phone number associated with the eSign invitation.  
3. Check your email or SMS for the OTP.  
4. Input the OTP and click **Proceed**.  
5. Access the document and proceed with the signing/reviewing process.