The DES Challenges were a series of brute force attack

Brute force attack

In cryptography, a brute-force attack, or exhaustive key search, is a strategy that can, in theory, be used against any encrypted data. Such an attack might be utilized when it is not possible to take advantage of other weaknesses in an encryption system that would make the task easier...

 contests created by RSA Security

RSA Security

RSA, the security division of EMC Corporation, is headquartered in Bedford, Massachusetts, United States, and maintains offices in Australia, Ireland, Israel, the United Kingdom, Singapore, India, China, Hong Kong and Japan....

 for the purpose of highlighting the lack of security provided by the Data Encryption Standard

Data Encryption Standard

The Data Encryption Standard is a block cipher that uses shared secret encryption. It was selected by the National Bureau of Standards as an official Federal Information Processing Standard for the United States in 1976 and which has subsequently enjoyed widespread use internationally. It is...

.

The Contests

The first challenge began in 1997 and was solved in 96 days by the DESCHALL Project

DESCHALL Project

DESCHALL, short for DES Challenge, was the first group to publicly break a message which used the Data Encryption Standard , becoming the $10,000 winner of the first of the set of DES Challenges proposed by RSA Security in 1997...

.

DES Challenge II-1 was solved by distributed.net

Distributed.net

distributed.net is a worldwide distributed computing effort that is attempting to solve large scale problems using otherwise idle CPU or GPU time. It is officially recognized as a non-profit organization under U.S...

 in 41 days in early 1998. The plaintext was "The secret message is: Many hands make light work."

DES Challenge II-2 was solved in just 56 hours in July 1998 by the Electronic Frontier Foundation

Electronic Frontier Foundation

The Electronic Frontier Foundation is an international non-profit digital rights advocacy and legal organization based in the United States...

 (EFF) with their purpose-built Deep Crack

EFF DES cracker

In cryptography, the EFF DES cracker is a machine built by the Electronic Frontier Foundation in 1998 to perform a brute force search of DES cipher's key space — that is, to decrypt an encrypted message by trying every possible key...

 machine. The prize for the contest was US$10,000 whilst the machine cost US$250,000 to build. The contest demonstrated how quickly a rich corporation or government agency, having built a similar machine, could decrypt ciphertext encrypted with DES. The text was revealed to be "The secret message is: It's time for those 128-, 192-, and 256-bit keys."

DES Challenge III was completed as a joint effort between distributed.net and Deep Crack. The key was found in just 22 hours 15 minutes in January 1999, and the plaintext was See you in Rome (second AES Conference, March 22-23, 1999).

Reaction

Many cryptographers assumed that once the DES had been shown to be breakable, the Federal Authorities would withdraw the standard, however this did not happen. FBI

Federal Bureau of Investigation

The Federal Bureau of Investigation is an agency of the United States Department of Justice that serves as both a federal criminal investigative body and an internal intelligence agency . The FBI has investigative jurisdiction over violations of more than 200 categories of federal crime...

 director Louis Freeh told Congress. "That is not going to make a difference in a kidnapping case. It is not going to make a difference in a national security case. We don't have the technology or the brute force capability to get to this information."

It was not until special purpose hardware brought the time down below 24 hours that both industry and federal authorities had to admit that the DES was no longer viable. Although the National Institute of Standards and Technology

National Institute of Standards and Technology

The National Institute of Standards and Technology , known between 1901 and 1988 as the National Bureau of Standards , is a measurement standards laboratory, otherwise known as a National Metrological Institute , which is a non-regulatory agency of the United States Department of Commerce...

 started work on what became the Advanced Encryption Standard

Advanced Encryption Standard

Advanced Encryption Standard is a specification for the encryption of electronic data. It has been adopted by the U.S. government and is now used worldwide. It supersedes DES...

 in 1997, they continued to endorse the DES as late as October 1999, with FIPS 46-3, although Triple DES

Triple DES

In cryptography, Triple DES is the common name for the Triple Data Encryption Algorithm block cipher, which applies the Data Encryption Standard cipher algorithm three times to each data block....

was preferred.