Audience: Everyone
The short answer: Cosigner authentication is an additional security layer that verifies the identity of co-located signers when multiple signers share a single device to complete a transaction. It is automatically enabled for all organizations that use co-located signing.
How it works
Co-located signers have different experiences depending on whether they already have a Proof account:
-
New user
- Proceeds with the transaction as usual — no PIN required.
-
Existing Proof user
- Receives a personal identification number (PIN) at the email address associated with their Proof account.
- Provides the PIN to verify identity.
- Proceeds to the transaction on the shared device.
-
Existing user with advanced security (e.g., multi-factor authentication or single sign-on)
- Cannot complete the transaction on a shared device.
- Must use a separate device to maintain the integrity of their advanced security settings.
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If a signer doesn't receive the PIN, they can verify the email address is correct, check their spam folder, or select the link to resend the code.
Summary Checklist
- Automatically enabled for all orgs using co-located signing — no setup required.
- Existing users receive a PIN by email. New users proceed without a PIN.
- Users with MFA or SSO must use a separate device — they cannot complete on a shared device.
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Still unsure? Contact Proof Support for help.
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