Several cryptographic constructs are involved in supporting the PEM message processing procedure. A set of fundamental elements is assumed. Data Encrypting Keys (DEKs) are used to encrypt message text and (for some MIC computation algorithms) in the message integrity check (MIC) computation process. Interchange Keys (IKs) are used to encrypt DEKs and MICs for transmission with messages. In a certificate-based asymmetric key management architecture, certificates are used as a means to provide entities' public components and other information in a fashion which is securely bound by a central authority. The remainder of this section provides more information about these constructs.