Cryptology From paper and pencil, mechanical devices to computers

1
CryptologyFrom paper and pencil, mechanical
devices to computers

• Time changes Earlier secret tactical
  com-munication involving few people are replaced
  by other environments and applications due to
  computers.
• Electronic commerce, www-communication, and
  mobile communication introduce other needs that
  we try to satisfy with cryptographic methods.
• Crypto-based methods are a mean för achieving
  these goals. Analyses of classical ciphers are
  often based on results from probability theory
  while modern public-key methods are based on
  number theory and abstract algebra.
• Designing a whole system correctly is very
  difficult. It is a well-known fact that many
  standard methods have weaknesses making them
  easy to crack.

• We would like to
• ensure confidentiality (as above)
• be sure sure that information has not been
  tampered with (integrity)
• know that the data origin is authentic
• be convinced that the user is as claimed
  (identification)
• stop a sender from denying messages sent
  (non-repudiation)

A real classical cipher. Spartan, circa 2500
years of age.

Preresquisites Algorithms and data structures,
operating systems, and algebra. Goal To convey
knowledge and abilities on algorithms and
protocols for the services listed on the left.