Cipher Block Modes of Operation

• Block ciphers process one n-bit block of data at a time

• Break long amounts of plaintext into 64-bit blocks

• Use Electronic Code Book (ECB)

  • Each block of plaintext is encrypted using the same key
  • Entry for every possible 64-bit plaintext pattern
  • Block appears more than once, produce same ciphertext
  • Repeating patterns become a problem