Purpose of Cryptography is to protect information from being read and understood by anyone except the intended recipient.

In practice encryption can be a function of time, the effort and time required for an unauthorized person is so large it is impractical.  By the time it is decrypted it is of little value.

Block Cipher – Breaks the plaintext into blocks and encrypts each with the same algorithm

Cipher – Cryptographic transformation operates on the characters or bites

Ciphertext or Cryptogram – unintelligible message

Clustering – plaintext message generates identical ciphertext using the same algorithm but different keys

Codes – A cryptographic transformation that operates at the word or phrase level

Cryptanalysis – act of obtaining plaintext or key from ciphertext

Cryptographic Algorithm – Step-by-step procedure used to encipher plaintext and decipher ciphertext

Cryptography – Art and Science of hiding the meaning of communication

Cryptology – encompasses cryptography and cryptanalysis

Cryptosystem – set of transformations from message space to ciphertext space

Decipher - to undo cipherment process

Encipher – to make a message unintelligible to all except recipient

End-to-end encryption – Encrypted information that is sent from sender to receiver