Key-Based SecurityAll security in key; alg can be published

• EK1 (M)= C, DK2 (C) = M

  keyspace -- range of possible key values
  

• Symmetric algorithms: encryption key can be calculated from decryption key and vice versa (usually same)

  • stream ciphers -- operate on plaintext a bit (byte) at a time
  • block ciphers -- operate on group (block) of bits.

Previous slide

Next slide

Back to first slide

View graphic version