xjava.security

Class KeyGenerator

public abstract class KeyGenerator extends Object implements Parameterized

The KeyGenerator class is used to generate keys for a given algorithm. Key generators are constructed using the getInstance factory methods (static methods that return instances of a given class).

The KeyGenerator interface is entirely algorithm independent, and, as for the KeyPairGenerator instances, KeyGenerator instances may be cast to algorithm-specific interfaces defined elsewhere in the Java Cryptography Architecture.

A typical set of calls would be:

    import java.security.KeyGenerator;
 
SecureRandom random = new SecureRandom(); KeyGenerator keygen = KeyGenerator.getInstance("DES"); keygen.initialize(random); Key key = keygen.generateKey();

Copyright © 1997 Systemics Ltd on behalf of the Cryptix Development Team.
All rights reserved.

$Revision: 1.3 $

Since: IJCE 1.0.0

Author: David Hopwood Raif S. Naffah

Constructor Summary
protected KeyGenerator(String algorithm)
Creates a KeyGenerator object for the specified algorithm.
Method Summary
Objectclone()
Returns a clone of this key generator.
protected ObjectengineGetParameter(String param)
SPI: Gets the value of the specified algorithm parameter.
protected voidengineSetParameter(String param, Object value)
SPI: Sets the specified algorithm parameter to the specified value.
abstract SecretKeygenerateKey()
Generates a key.
StringgetAlgorithm()
Returns the standard name of the algorithm for this key generator.
static String[]getAlgorithms(Provider provider)
Gets the standard names of all KeyGenerators implemented by a provider.
static String[]getAlgorithms()
Gets the standard names of all KeyGenerators implemented by any installed provider.
static KeyGeneratorgetInstance(String algorithm)
Generates a KeyGenerator object that implements the algorithm requested, as available in the environment.
static KeyGeneratorgetInstance(String algorithm, String provider)
Generates a KeyGenerator object implementing the specified algorithm, as supplied from the specified provider, if such an algorithm is available from the provider.
ObjectgetParameter(String param)
Gets the value of the specified algorithm parameter.
abstract voidinitialize(SecureRandom random)
Initializes the key generator.
voidsetParameter(String param, Object value)
Sets the specified algorithm parameter to the specified value.
StringtoString()

Constructor Detail

KeyGenerator

protected KeyGenerator(String algorithm)
Creates a KeyGenerator object for the specified algorithm.

Parameters: algorithm the standard string name of the algorithm.

Throws: NullPointerException if algorithm == null

Method Detail

clone

public Object clone()
Returns a clone of this key generator.

Note: In JavaSoft's version of JCE, KeyGenerator.clone() is protected. This is not very useful, since then an application (as opposed to the key generator implementation itself) is not able to call it.

Throws: CloneNotSupportedException if the key generator is not cloneable.

engineGetParameter

protected Object engineGetParameter(String param)
SPI: Gets the value of the specified algorithm parameter.

This method supplies a general-purpose mechanism through which it is possible to get the various parameters of this object. A uniform algorithm-specific naming scheme for each parameter is desirable but left unspecified at this time.

The default implementation always throws a NoSuchParameterException.

This method is not supported in JavaSoft's version of JCE.

Parameters: param the string name of the parameter.

Returns: the object that represents the parameter value.

Throws: NoSuchParameterException if there is no parameter with name param for this key generator implementation. InvalidParameterException if the parameter exists but cannot be read.

engineSetParameter

protected void engineSetParameter(String param, Object value)
SPI: Sets the specified algorithm parameter to the specified value.

This method supplies a general-purpose mechanism through which it is possible to set the various parameters of this object. A uniform algorithm-specific naming scheme for each parameter is desirable but left unspecified at this time.

The default implementation always throws a NoSuchParameterException.

This method is not supported in JavaSoft's version of JCE.

Parameters: param the string name of the parameter. value the parameter value.

Throws: NoSuchParameterException if there is no parameter with name param for this key generator implementation. InvalidParameterException if the parameter exists but cannot be set. InvalidParameterTypeException if value is the wrong type for this parameter.

generateKey

public abstract SecretKey generateKey()
Generates a key. This method generates a new key every time it is called.

Returns: the new key.

getAlgorithm

public String getAlgorithm()
Returns the standard name of the algorithm for this key generator.

See International JCE Standard Algorithm Names for a list of KeyGenerator algorithm names.

Returns: the standard string name of the algorithm.

getAlgorithms

public static String[] getAlgorithms(Provider provider)
Gets the standard names of all KeyGenerators implemented by a provider.

This method is not supported in JavaSoft's version of JCE. For compatibility you may wish to use IJCE.getAlgorithms(provider, "KeyGenerator") instead.

Since: IJCE 1.0.1

getAlgorithms

public static String[] getAlgorithms()
Gets the standard names of all KeyGenerators implemented by any installed provider. Algorithm names are not duplicated if they are supported by more than one provider.

This method is not supported in JavaSoft's version of JCE. For compatibility you may wish to use IJCE.getAlgorithms("KeyGenerator") instead.

Since: IJCE 1.0.1

getInstance

public static KeyGenerator getInstance(String algorithm)
Generates a KeyGenerator object that implements the algorithm requested, as available in the environment.

See International JCE Standard Algorithm Names for a list of KeyGenerator algorithm names.

Parameters: algorithm the standard name or an alias for the algorithm.

Returns: the new KeyGenerator object.

Throws: NoSuchAlgorithmException if the algorithm is not available in the environment.

getInstance

public static KeyGenerator getInstance(String algorithm, String provider)
Generates a KeyGenerator object implementing the specified algorithm, as supplied from the specified provider, if such an algorithm is available from the provider.

See International JCE Standard Algorithm Names for a list of KeyGenerator algorithm names.

Parameters: algorithm the standard name or an alias for the algorithm. provider the string name of the provider.

Returns: the new KeyGenerator object.

Throws: NoSuchAlgorithmException if the algorithm is not available from the provider. NoSuchProviderException if the provider is not available in the environment.

getParameter

public Object getParameter(String param)
Gets the value of the specified algorithm parameter.

This method supplies a general-purpose mechanism through which it is possible to get the various parameters of this object. A uniform algorithm-specific naming scheme for each parameter is desirable but left unspecified at this time.

This method is not supported in JavaSoft's version of JCE.

Parameters: param the string name of the parameter.

Returns: the object that represents the parameter value.

Throws: NullPointerException if param == null NoSuchParameterException if there is no parameter with name param for this key generator implementation. InvalidParameterException if the parameter exists but cannot be read.

initialize

public abstract void initialize(SecureRandom random)
Initializes the key generator.

Parameters: random a source of randomness for this generator.

setParameter

public void setParameter(String param, Object value)
Sets the specified algorithm parameter to the specified value.

This method supplies a general-purpose mechanism through which it is possible to set the various parameters of this object. A uniform algorithm-specific naming scheme for each parameter is desirable but left unspecified at this time.

This method is not supported in JavaSoft's version of JCE.

Parameters: param the string identifier of the parameter. value the parameter value.

Throws: NullPointerException if param == null NoSuchParameterException if there is no parameter with name param for this key generator implementation. InvalidParameterException if the parameter exists but cannot be set. InvalidParameterTypeException if value is the wrong type for this parameter.

toString

public String toString()