public class BCrypt extends Object
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.
| Constructor and Description |
|---|
BCrypt() |
| Modifier and Type | Method and Description |
|---|---|
static boolean |
checkpw(byte[] passwordb,
String hashed)
Check that a password (as a byte array) matches a previously hashed
one
|
static boolean |
checkpw(String plaintext,
String hashed)
Check that a plaintext password matches a previously hashed
one
|
static 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 String |
gensalt(int log_rounds)
Generate a salt for use with the BCrypt.hashpw() method
|
static String |
gensalt(int log_rounds,
SecureRandom random)
Generate a salt for use with the BCrypt.hashpw() method
|
static String |
gensalt(String prefix) |
static String |
gensalt(String prefix,
int log_rounds)
Generate a salt for use with the BCrypt.hashpw() method
|
static String |
gensalt(String prefix,
int log_rounds,
SecureRandom random)
Generate a salt for use with the BCrypt.hashpw() method
|
static String |
hashpw(byte[] passwordb,
String salt)
Hash a password using the OpenBSD bcrypt scheme
|
static String |
hashpw(String password,
String salt)
Hash a password using the OpenBSD bcrypt scheme
|
public static String hashpw(String password, String salt)
password - the password to hashsalt - the salt to hash with (perhaps generated
using BCrypt.gensalt)public static String hashpw(byte[] passwordb, String salt)
passwordb - the password to hash, as a byte arraysalt - the salt to hash with (perhaps generated
using BCrypt.gensalt)public static String gensalt(String prefix, int log_rounds, SecureRandom random) throws IllegalArgumentException
prefix - the prefix value (default $2a)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 useIllegalArgumentException - if prefix or log_rounds is invalidpublic static String gensalt(String prefix, int log_rounds) throws IllegalArgumentException
prefix - the prefix value (default $2a)log_rounds - the log2 of the number of rounds of
hashing to apply - the work factor therefore increases as
2**log_rounds.IllegalArgumentException - if prefix or log_rounds is invalidpublic static String gensalt(int log_rounds, SecureRandom random) throws IllegalArgumentException
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 useIllegalArgumentException - if log_rounds is invalidpublic static String gensalt(int log_rounds) throws IllegalArgumentException
log_rounds - the log2 of the number of rounds of
hashing to apply - the work factor therefore increases as
2**log_rounds.IllegalArgumentException - if log_rounds is invalidpublic static String gensalt()
public static boolean checkpw(String plaintext, String hashed)
plaintext - the plaintext password to verifyhashed - the previously-hashed passwordpublic static boolean checkpw(byte[] passwordb,
String hashed)
passwordb - the password to verify, as a byte arrayhashed - the previously-hashed passwordCopyright © 2020. All rights reserved.