Package org.apache.commons.codec.digest

Class Crypt

  • public class Crypt
extends java.lang.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

    • Constructor Summary

      Constructors 
      Constructor Description
      Crypt()  

    • Method Summary

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

        A salt is generated for you using ThreadLocalRandom; for more secure salts consider using SecureRandom to generate your own salts and calling crypt(byte[], String).

        Parameters:
        keyBytes - plaintext password
        Returns:
        hash value
        Throws:
        java.lang.IllegalArgumentException - when a NoSuchAlgorithmException is caught.

      • crypt

        public static java.lang.String crypt​(byte[] keyBytes,
                                     java.lang.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 - real salt value without prefix or "rounds=". The salt may be null, in which case a salt is generated for you using ThreadLocalRandom; for more secure salts consider using SecureRandom to generate your own salts.
        Returns:
        hash value
        Throws:
        java.lang.IllegalArgumentException - if the salt does not match the allowed pattern
        java.lang.IllegalArgumentException - when a NoSuchAlgorithmException is caught.

      • crypt

        public static java.lang.String crypt​(java.lang.String key)
        Calculates the digest using the strongest crypt(3) algorithm.

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

        A salt is generated for you using ThreadLocalRandom; for more secure salts consider using SecureRandom to generate your own salts and calling crypt(String, String).

        Parameters:
        key - plaintext password
        Returns:
        hash value
        Throws:
        java.lang.IllegalArgumentException - when a NoSuchAlgorithmException is caught.
        See Also:
        crypt(String, String)

      • crypt

        public static java.lang.String crypt​(java.lang.String key,
                                     java.lang.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 - real salt value without prefix or "rounds=". The salt may be null, in which case a salt is generated for you using ThreadLocalRandom; for more secure salts consider using SecureRandom to generate your own salts.
        Returns:
        hash value, i.e. encrypted password including the salt string
        Throws:
        java.lang.IllegalArgumentException - if the salt does not match the allowed pattern
        java.lang.IllegalArgumentException - when a NoSuchAlgorithmException is caught. *
        See Also:
        "The man page of the libc crypt (3) function."