Blowfish has a 64-bit block size and a variable key length – from 32 bits to 448 bits. It is a 16-round Feistel cipher and uses large key-dependent S-boxes. It is similar in structure to CAST-128, which uses fixed S-boxes.Since then Blowfish has been analyzed considerably, and is gaining acceptance as a strong encryption algorithm.
Blowfish was designed in 1993 by Bruce Schneier as a fast, free alternative to existing encryption algorithms. Since then it has been analyzed considerably, and it is slowly gaining acceptance as a strong encryption algorithm. Blowfish is unpatented and license-free, and is available free for all uses.
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 only known attacks against Blowfish are based on its weak key classes.
Blowfish encryption algorithm: General information
Block cipher: 64-bit block
Variable key length: 32 bits to 448 bits
Designed by Bruce Schneier
First published: 1993