25-10-2012, 02:00 PM
Blowfish Algorithm
blowfish.ppt (Size: 140 KB / Downloads: 31)
The Blowfish Encryption Algorithm
Blowfish is a keyed, symmetric block cipher, designed in 1993 by Bruce Schneier and included in a large number of cipher suites and encryption products. (Wikipedia)
Blowfish is a symmetric block cipher that can be used as a drop-in replacement for DES or IDEA. (Bruce Schneier)
Bruce Schneier
Bruce Schneier (born January 15, 1963) is an American cryptographer, computer security specialist, and writer.
He is the author of several books on computer security and cryptography, and is the founder and chief technology officer of Counterpane Internet Security.
The Original Blowfish
The original Blowfish paper was presented at the First Fast Software Encryption workshop in Cambridge, UK (proceedings published by Springer-Verlag, Lecture Notes in Computer Science #809, 1994) and the April 1994 issue of Dr. Dobb's Journal.
"Blowfish--One Year Later" appeared in the September 1995 issue of Dr. Dobb's Journal.
The Blowfish Algorithm: Key Expansion
The diagram to shows the action of Blowfish. Each line represents 32 bits. The algorithm keeps two subkey arrays: the 18-entry P-array and four 256-entry S-boxes.
The S-boxes accept 8-bit input and produce 32-bit output. One entry of the P-array is used every round, and after the final round, each half of the data block is XORed with one of the two remaining unused P-entries.