Introduction
In 1972, the National Institute of
Standards and Technology (NIST), then know by the name National Bureau of
Standards, requested proposals for a cryptographic algorithm that could be
used to protect nonclassified information.They wanted the algorithm to be very secure, inexpensive, easy to
understand and adaptable for diverse applications so that the algorithm
could be used by different institutions and by the general public.
In 1974 they made the request again as
they did not receive any viable proposals in 1972. This time IBM submitted
the Lucifer algorithm. The algorithm was forwarded to the National
Security Agency (NSA) to evaluate its security. NSA made some
modifications to the algorithms with the most important one being the
replacement of a 128bit key with a 56bit key.
Many people suspected that the modifications made by the NSA were deliberate to
make the algorithm weak and add a back door so that its agents would be
able to decrypt the encrypted messages without the key. Ignoring such
suspicions, NIST adopted the modified algorithm as a federal standard in
November 1976. The algorithm name was changed to the Data Encryption
Standard and published in January 1977 as FIPS PUB 46. Since then it has
been a widely used cryptographic algorithm for various application and the
suspicions slowly faded away as no one was able to find a back door to
attack DES.
Over the years, computers have become more powerful and various bruteforce attacks on the DES
undermined its capabilities as a powerful and secure cryptosystem. In
1997, NIST abandoned its official endorsment of DES as a federal standard
and started to work on a new algorithm called the Advanced Encryption
Standard that would replace DES.
