Package com.jalios.util

Class BCrypt

  • public class BCrypt
extends java.lang.Object
    BCrypt implements OpenBSD-style Blowfish password hashing using the scheme described in "A Future-Adaptable Password Scheme" by Niels Provos and David Mazieres.

    This password hashing system tries to thwart off-line password cracking using a computationally-intensive hashing algorithm, based on Bruce Schneier's Blowfish cipher. The work factor of the algorithm is parameterised, so it can be increased as computers get faster.

    Usage is really simple. To hash a password for the first time, call the hashpw method with a random salt, like this:

    String pw_hash = BCrypt.hashpw(plain_password, BCrypt.gensalt());

    To check whether a plaintext password matches one that has been hashed previously, use the checkpw method:

    if (BCrypt.checkpw(candidate_password, stored_hash))
        System.out.println("It matches");
    else
        System.out.println("It does not match");

    The gensalt() method takes an optional parameter (log_rounds) that determines the computational complexity of the hashing:

    String strong_salt = BCrypt.gensalt(10)
    String stronger_salt = BCrypt.gensalt(12)

    The amount of work increases exponentially (2**log_rounds), so each increment is twice as much work. The default log_rounds is 10, and the valid range is 4 to 30.

    Version:
    0.4
    Author:
    Damien Miller

    • Constructor Summary

      Constructors 
      Constructor Description
      BCrypt()  

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      static boolean checkpw​(java.lang.String plaintext, java.lang.String hashed)
      Check that a plaintext password matches a previously hashed one
      byte[] crypt_raw​(byte[] password, byte[] salt, int log_rounds, int[] cdata)
      Perform the central password hashing step in the bcrypt scheme
      static java.lang.String gensalt()
      Generate a salt for use with the BCrypt.hashpw() method, selecting a reasonable default for the number of hashing rounds to apply
      static java.lang.String gensalt​(int log_rounds)
      Generate a salt for use with the BCrypt.hashpw() method
      static java.lang.String gensalt​(int log_rounds, java.security.SecureRandom random)
      Generate a salt for use with the BCrypt.hashpw() method
      static java.lang.String hashpw​(java.lang.String password, java.lang.String salt)
      Hash a password using the OpenBSD bcrypt scheme

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Constructor Detail

      • BCrypt

        public BCrypt()

    • Method Detail

      • crypt_raw

        public byte[] crypt_raw​(byte[] password,
                        byte[] salt,
                        int log_rounds,
                        int[] cdata)
        Perform the central password hashing step in the bcrypt scheme
        Parameters:
        password - the password to hash
        salt - the binary salt to hash with the password
        log_rounds - the binary logarithm of the number of rounds of hashing to apply
        cdata - the plaintext to encrypt
        Returns:
        an array containing the binary hashed password

      • hashpw

        public static java.lang.String hashpw​(java.lang.String password,
                                      java.lang.String salt)
        Hash a password using the OpenBSD bcrypt scheme
        Parameters:
        password - the password to hash
        salt - the salt to hash with (perhaps generated using BCrypt.gensalt)
        Returns:
        the hashed password

      • gensalt

        public static java.lang.String gensalt​(int log_rounds,
                                       java.security.SecureRandom random)
        Generate a salt for use with the BCrypt.hashpw() method
        Parameters:
        log_rounds - the log2 of the number of rounds of hashing to apply - the work factor therefore increases as 2**log_rounds.
        random - an instance of SecureRandom to use
        Returns:
        an encoded salt value

      • gensalt

        public static java.lang.String gensalt​(int log_rounds)
        Generate a salt for use with the BCrypt.hashpw() method
        Parameters:
        log_rounds - the log2 of the number of rounds of hashing to apply - the work factor therefore increases as 2**log_rounds.
        Returns:
        an encoded salt value

      • gensalt

        public static java.lang.String gensalt()
        Generate a salt for use with the BCrypt.hashpw() method, selecting a reasonable default for the number of hashing rounds to apply
        Returns:
        an encoded salt value

      • checkpw

        public static boolean checkpw​(java.lang.String plaintext,
                              java.lang.String hashed)
        Check that a plaintext password matches a previously hashed one
        Parameters:
        plaintext - the plaintext password to verify
        hashed - the previously-hashed password
        Returns:
        true if the passwords match, false otherwise