Domain 3 - Advanced Crypto Flashcards
Cipher Block Chaining (feedback in stream modes)
Uses the previous ciphertext from the previous block, and uses it to XOR’ the next block. First block uses an Initialization Vector.
DES ECB
Electronic Code BookNo initialization vectorsusceptible to replay attacks.
DES CBC
Cipher Block Chaining- Block Mode- XORs previous block as seed to next block- First encrypted block is IV for next.- Errors propogate. An error in one block propagates everywhere
DES CFB
Cipher Feedback - Stream- Uses feedback to destroy patterns- Uses IV - Errors propogate
DES - OFB
Output Feedback- XORs previous block as seed to next block- Stream cipher- Uses subkey before it is XORed to plaintext- Subkey is not affected by Encryption errors- errors don’t propagate
DES CTR
Counter- Uses a counter- Errors don’t propogate
2TDES
Two triple DES. Uses 1 key to encrypt, another to ‘decrypt’ and again key 1 to encrypt. Key length of 112 bits
3TDES
Strongest form, three triple des168 bits in key length
AES Functions
SubbytesShiftRowsMixColumnsAddRoundKey
AES data State
4 Rows of 4, 16 byte blocks
AES SubBytes
Uses substitution to add confusion
AES ShiftRows
Shifts the rows to add confusion
AES MixColumns
Provides diffusion by mixing the columns fo the state via finite field mathematics.
AES AddRoundKey
Final functionXORs the state with the subkey
MD5 creator
Ronald Rivest
