Message Authentication, Digital Signature, and Key Management

This chapter introduces the message authentication and digital signature to protect security aspects of message contents. Message authentication ensures that a message is received from the alleged sender and in its original form. The chapter describes some examples of both message authentication code (MAC) and secure hash functions. Data authentication algorithm is a MAC algorithm that applies block cipher data encryption standard in a cipher block chaining mode. Digital signature provides the security capability to achieve such a goal. Thus, a digital signature function includes the authentication function with additional capabilities. A variety of approaches have been proposed for the digital signature function. These approaches fall into two categories: direct digital signatures and arbitrated digital signature. The chapter discusses key management for different cryptographic systems. A public key cryptosystem can be applied to encrypt secret keys for distribution. A public‐key cryptosystem can be applied in a hybrid way.