Blowfish is a symmetric encryption algorithm designed in 1993 by Bruce Schneider as an alternative to existing encryption algorithms such as DES. Unlike DES, however, the Blowfish algorithm has a variable key length, which can be extended from 32 bits to 448 bits, making this a more secure alternative. Blowfish is a 64-bit cipher (i.e. a cryptographic key and algorithm are applied to a block of data rather than single bits).

Blowfish is a fast, free alternative to existing algorithms and has been analyzed considerably through years of peer review.

Length = Strength

Finding the plain text of an encrypted message without knowing the key is called "cracking" an algorithm. This brute-force attack consists of trying all possible values of keys until the right one is found.

It is easy to demonstrate that in the case of brute-force attack, the security increases together with the length of the key. If the key is 8 bits long, there are 2(to the power of 8), or 256 possible combinations. With a key of 40 bits this is increased to 2(to the power of 40), or one thousand billion combinations. The protection then resides on the time needed for a computer to perform its attack. Based on these premises as well as numerous industry trials, it is common opinion today that

• 40-bit key algorithms are useless as they can be "cracked" within a few hours by an average personal computer.
• 64-bit algorithms are safe today but will become threatened as technology evolves.
• 128-bit and over algorithms are almost unbreakable. In other words, it would take millions of years to try every possible combination of bits in a 128-bit key.

Based on calculations it can be said that a 128-bit encryption is not just three times stronger than a 40-bit encryption—it is 309,485,009,821,345,068,724,781,056 times stronger. Likewise, a 448-bit encryption key is 2.1 x 1096 times stronger than a 128-bit key.

Conclusion

Backup Proshop considered many factors when choosing Blowfish as its encryption technology, including peer review, speed and key strength. It is clear that Blowfish will set the standard for years to come, and will continue to be the preferred encryption algorithm for corporations worldwide.