Steklov Institute St. Petersburg
Technische Universität München
State University St. Petersburg
Joint Advanced Student School (JASS)
Course 1: Algorithms in IT Security
St. Petersburg - Wednesday, March 30 through Saturday, April 9, 2005
Practical Private Key Cryptography
Private key cryptography is an approach to private information transfer based on the idea of a
shared secret key. It is one of the most commonly used in practice because of its performance
and its simplicity in implementation.
The main concept: Alice and Bob have a given key K in common knowledge.
Alice enciphers a message using K, and Bob deciphers the message using K.
Noone who doesn't know K can read the message.
In this article this concept is briefly described. Then, the DES cipher, the most popular standard
in private key cryptography, and the ways of his cracking is considered.