Cryptography

A generic cryptography model is shown in the following diagram:

In the preceding diagram, P, E, C, and D represent plaintext, encryption, ciphertext, and decryption, respectively. Also based on this model, explanations of concepts such as entity, sender, receiver, adversary, key, and channel follow:

• Entity: Either a person or system that sends, receives, or performs operations on data
• Sender: This is an entity that transmits the data
• Receiver: This is an entity that takes delivery of the data
• Adversary: This is an entity that tries to circumvent the security service
• Key: A key is data that is used to encrypt or decrypt other data
• Channel: Channel provides a medium of communication between entities

Next, we will describe the cryptography services mentioned earlier in the chapter in greater detail.