Who issues User (Entrust/Direct) Certificates and how are they used?

User Certificates are issued by the USPTO Certification Authority. The USPTO Certification Authority (CA) issues digital certificates that bind identity and other information to an electronic key used to encrypt and sign digital information. By issuing a certificate, the CA confirms the accuracy of the certificate information. The user's certificate is unique. No other certificate, from whatever source, may be used as a substitute. The user's unique certificate provides the means to identify and authenticate a USPTO customer. Additionally, it provides the means to set up, and conduct, fully encrypted sessions between the user and USPTO on confidential patent application matters.

USPTO FAQ - Questions and Answers (30JUL2004)