NAME: Twofish
CREATOR: Bruce Schneier, John Kelsey, Doug Whiting, David Wagner, Chris Hall, Niels Ferguson
PB AUTHOR: Greg Turgeon
DESCRIPTION: Twofish is a 128-bit block cipher that accepts a variable-length key up to 256 bits. The cipher is a 16-round Feistel network with a bijective F function made up of four key-dependent 8-by-8-bit S-boxes, a fixed 4-by-4 maximum distance separable matrix over GF(28), a pseudo-Hadamard transform, bitwise rotations, and a carefully designed key schedule. A fully optimized implementation of Twofish encrypts on a Pentium Pro at 17.8 clock cycles per byte, and an 8-bit smart card implementation encrypts at 1820 clock cycles per byte. Twofish can be implemented in hardware in 14000 gates. The design of both the round function and the key schedule permits a wide variety of tradeoffs between speed, software size, key setup time, gate count, and memory.
NOTES: Information about Twofish can be obtained from Counterpane Labs at http://www.counterpane.com/twofish.htm. The Twofish algorithm is unpatented, uncopyrighted, and free for any use public or private, commercial or non-commercial.
SOURCE: http://www.powerbasic.com/support/forums/Forum7/HTML/001976.html