In contrast, Closed-Loop Authentication is when the same party that provided Credential Enrollment provides the Authentication.
In Open-Loop Authentication a Identity Provider (IDP) issues a cryptographic credential to the user’s device and then is "out of the loop" when the device presents the credential to a Relying Party.[1]
Credentials used in Open-Loop Authentication are typically Public Key Certificates, but could also be U-Prove tokens or Idemix anonymous credentials.