Cipher Modes Online version This will help with the Cipher Modes content of the Security+. by Brody Campbell 1 Electronic Code Book 2 Cipher Block Chaining 3 Counter 4 Galois/Counter Mode Simplest Divide plaintext into blocks, encrypts blocks using same key Not recommended Uses an IV for randomness when encrypting the first block Combines each block with the previous using XOR Suffers from pipeline delays as encryption is dependent on encrypting every previous block Coverts a block cipher to a stream sipher Combines an IV with a counter, uses results to encrypt each plaintext block Each block uses the same IV but CTM combines it with the counter resulting in a different encryption for each block Multiprocessor systems can encrypt/decrypt multiple blocks at the same time Respected secure mode of operation Represented as CTR or CM Used by many block ciphers Combines counter with galois method of authentication Provides authenticity/integrity and confidentiality includes hashing techniques for integrity Widely used due to it's efficiency
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