cn.pengh.crypt

类 BCrypt

java.lang.Object

cn.pengh.crypt.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 31.

构造器概要

构造器

构造器和说明
BCrypt()

方法概要

限定符和类型	方法和说明
static boolean	checkpw(java.lang.String plaintext, java.lang.String hashed) Check that a plaintext password matches a previously hashed one
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

从类继承的方法 java.lang.Object

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

构造器详细资料

BCrypt

public BCrypt()

方法详细资料

hashpw

public static java.lang.String hashpw(java.lang.String password,
                                      java.lang.String salt)

Hash a password using the OpenBSD bcrypt scheme

参数:

password - the password to hash

salt - the salt to hash with (perhaps generated using BCrypt.gensalt)

返回:

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

参数:

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

返回:

an encoded salt value

gensalt

public static java.lang.String gensalt(int log_rounds)

Generate a salt for use with the BCrypt.hashpw() method

参数:

log_rounds - the log2 of the number of rounds of hashing to apply - the work factor therefore increases as 2**log_rounds.

返回:

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

返回:

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

参数:

plaintext - the plaintext password to verify

hashed - the previously-hashed password

返回:

true if the passwords match, false otherwise