net.sf.mmm.crypto.hash

Class HashConfig

java.lang.Object

net.sf.mmm.crypto.CryptoConfig

net.sf.mmm.crypto.algorithm.CryptoAlgorithmConfig

net.sf.mmm.crypto.hash.HashConfig

All Implemented Interfaces:

AbstractCryptoFactory, AbstractGetIterationCount, CryptoAlgorithm, HashFactory

Direct Known Subclasses:

Md5, Sha1, Sha2

public class HashConfig
extends CryptoAlgorithmConfig
implements AbstractGetIterationCount, HashFactory

CryptoAlgorithmConfig for hashing.

Since:

1.0.0

Author:

Joerg Hohwiller (hohwille at users.sourceforge.net)

Field Summary

Fields

Modifier and Type	Field and Description
static String	ALGORITHM_NONE The dummy hash algorithm NONE for no hashing (e.g.
private int	iterationCount

Fields inherited from class net.sf.mmm.crypto.algorithm.CryptoAlgorithmConfig

algorithm

Fields inherited from class net.sf.mmm.crypto.CryptoConfig

provider

Constructor Summary

Constructors

Constructor and Description
HashConfig(String algorithm) The constructor.
HashConfig(String algorithm, int iterationCount) The constructor.
HashConfig(String algorithm, SecurityProvider provider) The constructor.
HashConfig(String algorithm, SecurityProvider provider, int iterationCount) The constructor.

Method Summary

Modifier and Type	Method and Description
HashConfig	decrementIterationCount()
int	getIterationCount()
HashAccess	newAccess()
HashCreator	newHashCreator()

Methods inherited from class net.sf.mmm.crypto.algorithm.CryptoAlgorithmConfig

getAlgorithm

Methods inherited from class net.sf.mmm.crypto.CryptoConfig

getProvider

Methods inherited from class java.lang.Object

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

Field Detail

ALGORITHM_NONE

public static final String ALGORITHM_NONE

The dummy hash algorithm NONE for no hashing (e.g. plain signing without prior hashing).

See Also:

Constant Field Values

iterationCount

private final int iterationCount

Constructor Detail

HashConfig

public HashConfig(String algorithm)

The constructor.

Parameters:

algorithm - the hash algorithm.

HashConfig

public HashConfig(String algorithm,
                  int iterationCount)

The constructor.

Parameters:

algorithm - the hash algorithm.

iterationCount - the iteration count.

HashConfig

public HashConfig(String algorithm,
                  SecurityProvider provider)

The constructor.

Parameters:

algorithm - the hash algorithm.

provider - the SecurityProvider.

HashConfig

public HashConfig(String algorithm,
                  SecurityProvider provider,
                  int iterationCount)

The constructor.

Parameters:

algorithm - the hash algorithm.

provider - the SecurityProvider.

iterationCount - the iteration count.

Method Detail

getIterationCount

public int getIterationCount()

Specified by:

getIterationCount in interface AbstractGetIterationCount

Returns:

the iteration count representing the number of repetitive iterations of an algorithm such as a hash function. A value of 1 means that the algorithm is applied only a single time. This can be fine for simple hashing. Any higher number means an according repetition of the algorithm. The higher the number the higher the computation time. While e.g. for password checks a high iteration count may only mean an overhead of roughly one second, an attacker who wants to try every password with a brute force attack will require an extra ordinary magnitude of additional computing power. Therefore in case of a password algorithm such as PBKDF2 a higher number will mean higher security. However, the value is always a trade-off between usability and security. Further, a too high number might even open the door to denial of service attacks (DoS). A good value can only be defined for a particular algorithm in combination of the current hardware resources and computation power that increase over time.

See Also:

PBEKeySpec.getIterationCount()

decrementIterationCount

public HashConfig decrementIterationCount()

Returns:

a HashConfig with the same algorithm but an iteration count decreased by 1. If the iteration count is already 1 then null is returned.

newAccess

public HashAccess newAccess()

Returns:

a new HashAccess for this configuration.

newHashCreator

public HashCreator newHashCreator()

Specified by:

newHashCreator in interface HashFactory

Returns:

a new instance of HashCreator for the configured hash algorithm of this factory.