R

Remote Authentication Dial-In User Service (RADIUS)
A standard for authenticating the identity of remote dial-in users.

Realm
A unique name given to each protected area on a server, whether it be a single document or an entire server.

Registration Authority (RA)
The RA is responsible for the identification and authentication of certificate Subscribers before issuing certificates, but does not sign or issue the certificates.

Relying Party
The Relying Party is a person or agency who has received information that includes a certificate and a digital signature verifiable with reference to a public key listed in the certificate, and is in a position to rely on them. The Relying Party relies on the validity of the binding of the Subscriber's name to a public key. The Relying Party is responsible for deciding whether or how to check the validity of the certificate by checking the appropriate certificate status information. The Relying Party can use the certificate to verify the integrity of a digitally-signed message to identify the creator of the message, or to establish confidential communications with the holder of the certificate. A Relying Party may use information in the certificate to determine the suitability of the certificate for a particular use. The Relying Party is the owner of the application.

Rights
The privileges a user or role has on a system.

Roles
A working description of a user. Roles are assigned rights.

Root Certificate
A self signed certificate issued from a root level Certificate Authority (CA).

RSA Encryption (Rivest-Sharmir-Adelman)
A popular encryption and authentication standard that uses asymmetric keys and was developed by Rivest, Sharmir, and Adelman. Based on a public key system, every user has 2 digital keys, one to encrypt information, and the other to decrypt. Authentication of both sender and recipient is achieved with this method.