jBCrypt is an implementation the OpenBSD Blowfish password hashing algorithm, as described in "A Future-Adaptable Password Scheme" by Niels Provos and David Mazieres: http://www.openbsd.org/papers/bcrypt-paper.ps
This system hashes passwords using a version of Bruce Schneier's Blowfish block cipher with modifications designed to raise the cost of off-line password cracking. The computation cost of the algorithm is parameterised, so it can be increased as computers get faster.
JUnit regression tests are available in in TestBCrypt.java
jBCrypt is licensed under a ISC/BSD licence. See the LICENSE file for details.
Please report bugs to Damien Miller djm@mindrot.org. Please check the TODO file first, in case your problem is something I already know about (please send patches!)
A simple example that demonstrates most of the features:
// Hash a password for the first time
String hashed = BCrypt.hashpw(password, BCrypt.gensalt());
// gensalt's log_rounds parameter determines the complexity
// the work factor is 2**log_rounds, and the default is 10
String hashed = BCrypt.hashpw(password, BCrypt.gensalt(12));
// Check that an unencrypted password matches one that has
// previously been hashed
if (BCrypt.checkpw(candidate, hashed))
System.out.println("It matches");
else
System.out.println("It does not match");
There is also a C#/.NET port by Derek Slager: