org.apache.commons.codec.digest

Class Crypt

java.lang.Object

org.apache.commons.codec.digest.Crypt

public class Crypt
extends Object

GNU libc crypt(3) compatible hash method.

See crypt(String, String) for further details.

This class is immutable and thread-safe.

Since:

1.7

Version:

$Id: Crypt.java 1744646 2016-05-20 00:11:45Z sebb $

Constructor Summary

Constructors

Constructor and Description
Crypt()

Method Summary

Modifier and Type	Method and Description
static String	crypt(byte[] keyBytes) Encrypts a password in a crypt(3) compatible way.
static String	crypt(byte[] keyBytes, String salt) Encrypts a password in a crypt(3) compatible way.
static String	crypt(String key) Calculates the digest using the strongest crypt(3) algorithm.
static String	crypt(String key, String salt) Encrypts a password in a crypt(3) compatible way.

Methods inherited from class java.lang.Object

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

Constructor Detail

Crypt

public Crypt()

Method Detail

crypt

public static String crypt(byte[] keyBytes)

Encrypts a password in a crypt(3) compatible way.

A random salt and the default algorithm (currently SHA-512) are used. See crypt(String, String) for details.

Parameters:

keyBytes - plaintext password

Returns:

hash value

Throws:

RuntimeException - when a NoSuchAlgorithmException is caught.

crypt

public static String crypt(byte[] keyBytes,
                           String salt)

Encrypts a password in a crypt(3) compatible way.

If no salt is provided, a random salt and the default algorithm (currently SHA-512) will be used. See crypt(String, String) for details.

Parameters:

keyBytes - plaintext password

salt - salt value

Returns:

hash value

Throws:

IllegalArgumentException - if the salt does not match the allowed pattern

RuntimeException - when a NoSuchAlgorithmException is caught.

crypt

public static String crypt(String key)

Calculates the digest using the strongest crypt(3) algorithm.

A random salt and the default algorithm (currently SHA-512) are used.

Parameters:

key - plaintext password

Returns:

hash value

Throws:

RuntimeException - when a NoSuchAlgorithmException is caught.

See Also:

crypt(String, String)

crypt

public static String crypt(String key,
                           String salt)

Encrypts a password in a crypt(3) compatible way.

The exact algorithm depends on the format of the salt string:

• SHA-512 salts start with $6$ and are up to 16 chars long.
• SHA-256 salts start with $5$ and are up to 16 chars long
• MD5 salts start with $1$ and are up to 8 chars long
• DES, the traditional UnixCrypt algorithm is used with only 2 chars
• Only the first 8 chars of the passwords are used in the DES algorithm!

The magic strings "$apr1$" and "$2a$" are not recognized by this method as its output should be identical with that of the libc implementation.

The rest of the salt string is drawn from the set [a-zA-Z0-9./] and is cut at the maximum length of if a "$" sign is encountered. It is therefore valid to enter a complete hash value as salt to e.g. verify a password with:

 storedPwd.equals(crypt(enteredPwd, storedPwd))
 

The resulting string starts with the marker string ($n$), where n is the same as the input salt. The salt is then appended, followed by a "$" sign. This is followed by the actual hash value. For DES the string only contains the salt and actual hash. The total length is dependent on the algorithm used:

• SHA-512: 106 chars
• SHA-256: 63 chars
• MD5: 34 chars
• DES: 13 chars

Example:

      crypt("secret", "$1$xxxx") => "$1$xxxx$aMkevjfEIpa35Bh3G4bAc."
      crypt("secret", "xx") => "xxWAum7tHdIUw"
 

This method comes in a variation that accepts a byte[] array to support input strings that are not encoded in UTF-8 but e.g. in ISO-8859-1 where equal characters result in different byte values.

Parameters:

key - plaintext password as entered by the used

salt - salt value

Returns:

hash value, i.e. encrypted password including the salt string

Throws:

IllegalArgumentException - if the salt does not match the allowed pattern

RuntimeException - when a NoSuchAlgorithmException is caught. *

See Also:

"The man page of the libc crypt (3) function."