This KDF was added in v0.5.0.
Password-Based Key Derivation Function 2 is an adaptive derivation function which uses an internal pseudorandom function (PRF) and iterates it many times over a password and salt (at least 16 bytes).
The PRF is recommended to be
HMAC/SHA-512. The use of an HMAC cryptographic hash function mitigates a length extension attack.
The recommended minimum number of iterations is 160,000 (as of 2/1/2016 on commodity hardware). This number should be doubled every two years (see schedule below or use
PBKDF2CipherProviderGroovyTest#testDefaultConstructorShouldProvideStrongIterationCount()to calculate safe minimums).
This KDF is not memory-hard (can be parallelized massively with commodity hardware) but is still recommended as sufficient by NIST SP 800-132 (PDF) and many cryptographers (when used with a proper iteration count and HMAC cryptographic hash function).