DES TEXT BOOK CONTENT
The most widely used encryption scheme is based on the Data Encryption Standard (DES) adopted in 1977 by the National Bureau of Standards, now the National Institute of Standards and Technology (NIST), as Federal Information Processing Standard 46 (FIPS PUB 46). The algorithm itself is referred to as the Data Encryption Algorithm (DEA).7 For DES,data are encrypted in 64-bit blocks using a 56-bit key.The algorithm transforms 64-bit input in a series of steps into a 64-bit output.The same steps,with the same key,are used to reverse the encryption. The DES enjoys widespread use.It has also been the subject of much controversy concerning how secure the DES is.To appreciate the nature of the controversy,let us quickly review the history of the DES. In the late 1960s,IBM set up a research project in computer cryptography led by Horst Feistel.The project concluded in 1971 with the development of an algorithm with the designation LUCIFER [FEIS73], which was sold to Lloyd’s of London for us...