Page 115 - CISSO_Prep_ Guide

• Decrypt/decipher/decode - the process of converting
ciphertext into plaintext
• Algorithm - the mathematical process used in the
encryption/decryption process
• Cryptosystem - the mechanism or device used for
encryption/decryption. The algorithm is a part of the
cryptosystem
• Initialization vector - a random value added to the initial
step of the encryption process to ensure that even similar
messages look different once encrypted.
• Substitution - replacing one value for another. For
example, the Caesar cipher replaced each letter of the
message with the letter three places further down the
alphabet.
• Transposition - changing the position of the letters so
that the letters in the ciphertext are not in the same order
as the letters in the plaintext
• Work factor - the amount of time or effort (resources)
needed to defeat a cryptosystem.

Symmetric Algorithms
Symmetric algorithms have been in use for thousands of years.
Their main benefit is protecting the confidentiality of messages.
The symmetric algorithm is one that uses the same key in the
encryption process as it does in the decryption process. The two
operations are really a mirror image of one another - therefore,
the use of the term symmetric.