Go implementation of bcrypt_pbkdf(3) from OpenBSD
(a variant of PBKDF2 with bcrypt-based PRF).


USAGE

  func Key(password, salt []byte, rounds, keyLen int) ([]byte, error)

  
  Key derives a key from the password, salt and rounds count, returning a
  []byte of length keyLen that can be used as cryptographic key.
  
  Remember to get a good random salt of at least 16 bytes.  Using a higher
  rounds count will increase the cost of an exhaustive search but will also
  make derivation proportionally slower.


REFERENCES

* http://www.tedunangst.com/flak/post/bcrypt-pbkdf
* http://cvsweb.openbsd.org/cgi-bin/cvsweb/src/lib/libutil/bcrypt_pbkdf.c
