Cryptography

• Cryptographers: (good guys)
  • Invent clever algorithms
• Cryptanalysts: (bad guys)
  • Attempt to break algorithms
• If lots of smart people have failed to solve a problem, then it probably won’t be solved, at least in near future.
• Cryptography systems depend upon computationally difficult problems which become simple when a secret (key) is known.

Is Algorithm Secret?

• Some believe that keeping the algorithm secret enhances its security
• Some believe that publishing the algorithm will enhance the security.
• Difficult to keep the algorithm secret
• Common practice: Commercial algorithms are public while military applications keep it secret.