Twofish Heads to Washington

A team led by Applied Cryptography author Bruce Schneier has invented a new block encryption algorithm and submitted it for consideration as the next new federal government standard for data scrambling.

Twofish, the sequel to Schneier's 5-year-old Blowfish block cypher, was submitted last week to the National Institute of Standards and Technology (NIST) for consideration as the Advanced Encryption Standard.

Twofish is designed to be flexible with respect to the necessary performance tradeoffs between the creation of a "secret key" and execution of the actual encryption. As such, it is well suited to large microprocessors, smart cards, and dedicated hardware.

"We designed Twofish with performance in mind," said Schneier, president of the security consulting firm Counterpane Systems. "You can get faster encryption with more setup time, or you could do no setup and get slower encryption," he said.

"You can trade off efficiencies between hardware, software, RAM vs ROM, encryption speed ... all of these are interoperable," Schneier said.

The free, publicly available algorithm is suitable for 128-, 192- or 256-bit key lengths.

The Advanced Encryption Standard is designed to replace the current government specification, known as the Data Encryption Standard, which was first introduced in 1977.

In submitting Twofish, Schneier's group joins about a dozen others aiming for the NIST standard, including IBM, RSA Data Security and Cylink.

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Photo of Bruce Schneier by Per Ervland.

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