Secure Communication Secure communication is the most straightforward use of cryptography. Two people may communicate securely by encrypting the messages sent between them. This can be done in such a way that a third party eavesdropping may never be able to decipher the messages. While secure communication has existed for centuries, the key management problem has prevented it from becoming commonplace. Identification and Authentication Identification and authentication are two widely used applications of cryptography.
Identification is the process of verifying someone's or something's identity.
This same process can be done electronically using cryptography. If the correct PIN is entered, the machine identifies that person as the rightful owner and grants access. Another important application of cryptography is authentication. Authentication merely determines whether that person or entity is authorized for whatever is in question. For more information on authentication and identification, see Question 2.2.5 .