The Blowfish algorithm is a symmetric block
cipher that can be used as a drop-in replacement for DES or
IDEA. It takes a variable-length key, from 32 bits to 448 bits,
making it ideal for both domestic and exportable use.
Blowfish is classified as public domain; as such
it has been analyzed extensively and gone through years of peer
review. At no point since it's initial release in 1993 has the
Blowfish code ever been cracked. This is significant when you
consider that the source code to the algorithm is freely
available.
Blowfish supports key lengths of 32 to 448
bits, making it one of the strongest encryption algorithms on
the market. Since the US government (NSA) has eliminated export
restrictions on encryption, Dialyourweb Backup is shipped with 448-bit
support standard.
Strength
The relative strength of the encryption
algorithm is based on key length. Bruce Schneier, creator of the
Blowfish encryption algorithm, has calculated that according to
what we know of quantum mechanics today, that the entire energy
output of the sun is insufficient to break a 197-bit key.
Here is a more generalized example:
The most common key lengths used by today’s web browsers are
"40-bit" and "128-bit." As a comparison, a 40-bit key can be
"cracked" within a few hours by an average personal computer.
However, a 128-bit key would take one BILLION powerful
computers, each capable of trying one BILLION keys per second.
In other words, it would take MILLIONS of years to try every
possible combination of bits in a 128-bit key.
In the preceding example, the 128-bit
encryption is not just three times stronger than 40-bit
encryption — it is 309,485,009,821,345,068,724,781,056 times
stronger. Performing this same analysis on a 448-bit encryption
key yields an encryption strength that is 2.1X1096 times
stronger than a 128-bit key.
Speed
The speed of the algorithm is also impressive.
Some may think a 448 bit key length is excessive. However, when
we analyze the effective throughput of the Blowfish algorithm,
we see that even large key lengths result in much faster
performance than other encryption algorithms.