java.security: public class: AlgorithmParameterGenerator

java.security
public class: AlgorithmParameterGenerator [javadoc | source]

java.lang.Object
   java.security.AlgorithmParameterGenerator

The AlgorithmParameterGenerator class is used to generate a set of parameters to be used with a certain algorithm. Parameter generators are constructed using the getInstance factory methods (static methods that return instances of a given class).

The object that will generate the parameters can be initialized in two different ways: in an algorithm-independent manner, or in an algorithm-specific manner:

The algorithm-independent approach uses the fact that all parameter generators share the concept of a "size" and a source of randomness. The measure of size is universally shared by all algorithm parameters, though it is interpreted differently for different algorithms. For example, in the case of parameters for the DSA algorithm, "size" corresponds to the size of the prime modulus (in bits). When using this approach, algorithm-specific parameter generation values - if any - default to some standard values, unless they can be derived from the specified size.
The other approach initializes a parameter generator object using algorithm-specific semantics, which are represented by a set of algorithm-specific parameter generation values. To generate Diffie-Hellman system parameters, for example, the parameter generation values usually consist of the size of the prime modulus and the size of the random exponent, both specified in number of bits.

In case the client does not explicitly initialize the AlgorithmParameterGenerator (via a call to an init method), each provider must supply (and document) a default initialization. For example, the Sun provider uses a default modulus prime size of 1024 bits for the generation of DSA parameters.

Also see:

AlgorithmParameters

java.security.spec.AlgorithmParameterSpec

author: Jan - Luehe

since: 1.2 -

Constructor:

Constructor:
protected AlgorithmParameterGenerator(AlgorithmParameterGeneratorSpi paramGenSpi, Provider provider, String algorithm) { this.paramGenSpi = paramGenSpi; this.provider = provider; this.algorithm = algorithm; } Creates an AlgorithmParameterGenerator object. Parameters: `paramGenSpi` - the delegate `provider` - the provider `algorithm` - the algorithm

 protected AlgorithmParameterGenerator(AlgorithmParameterGeneratorSpi paramGenSpi,
    Provider provider,
    String algorithm) {
        this.paramGenSpi = paramGenSpi;
        this.provider = provider;
        this.algorithm = algorithm;
}

Creates an AlgorithmParameterGenerator object.

Parameters:

paramGenSpi - the delegate

provider - the provider

algorithm - the algorithm

Method from java.security.AlgorithmParameterGenerator Summary:
generateParameters, getAlgorithm, getInstance, getInstance, getInstance, getProvider, init, init, init, init

Methods from java.lang.Object:
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method from java.security.AlgorithmParameterGenerator Detail:
public final AlgorithmParameters generateParameters() { return paramGenSpi.engineGenerateParameters(); } Generates the parameters.
public final String getAlgorithm() { return this.algorithm; } Returns the standard name of the algorithm this parameter generator is associated with.
public static AlgorithmParameterGenerator getInstance(String algorithm) throws NoSuchAlgorithmException { try { Object[] objs = Security.getImpl(algorithm, "AlgorithmParameterGenerator", (String)null); return new AlgorithmParameterGenerator ((AlgorithmParameterGeneratorSpi)objs[0], (Provider)objs[1], algorithm); } catch(NoSuchProviderException e) { throw new NoSuchAlgorithmException(algorithm + " not found"); } } Returns an AlgorithmParameterGenerator object for generating a set of parameters to be used with the specified algorithm. This method traverses the list of registered security Providers, starting with the most preferred Provider. A new AlgorithmParameterGenerator object encapsulating the AlgorithmParameterGeneratorSpi implementation from the first Provider that supports the specified algorithm is returned. Note that the list of registered providers may be retrieved via the Security.getProviders() method.
public static AlgorithmParameterGenerator getInstance(String algorithm, String provider) throws NoSuchProviderException, NoSuchAlgorithmException { if (provider == null \|\| provider.length() == 0) throw new IllegalArgumentException("missing provider"); Object[] objs = Security.getImpl(algorithm, "AlgorithmParameterGenerator", provider); return new AlgorithmParameterGenerator ((AlgorithmParameterGeneratorSpi)objs[0], (Provider)objs[1], algorithm); } Returns an AlgorithmParameterGenerator object for generating a set of parameters to be used with the specified algorithm. A new AlgorithmParameterGenerator object encapsulating the AlgorithmParameterGeneratorSpi implementation from the specified provider is returned. The specified provider must be registered in the security provider list. Note that the list of registered providers may be retrieved via the Security.getProviders() method.
public static AlgorithmParameterGenerator getInstance(String algorithm, Provider provider) throws NoSuchAlgorithmException { if (provider == null) throw new IllegalArgumentException("missing provider"); Object[] objs = Security.getImpl(algorithm, "AlgorithmParameterGenerator", provider); return new AlgorithmParameterGenerator ((AlgorithmParameterGeneratorSpi)objs[0], (Provider)objs[1], algorithm); } Returns an AlgorithmParameterGenerator object for generating a set of parameters to be used with the specified algorithm. A new AlgorithmParameterGenerator object encapsulating the AlgorithmParameterGeneratorSpi implementation from the specified Provider object is returned. Note that the specified Provider object does not have to be registered in the provider list.
public final Provider getProvider() { return this.provider; } Returns the provider of this algorithm parameter generator object.
public final void init(int size) { paramGenSpi.engineInit(size, new SecureRandom()); } Initializes this parameter generator for a certain size. To create the parameters, the `SecureRandom` implementation of the highest-priority installed provider is used as the source of randomness. (If none of the installed providers supply an implementation of `SecureRandom`, a system-provided source of randomness is used.)
public final void init(AlgorithmParameterSpec genParamSpec) throws InvalidAlgorithmParameterException { paramGenSpi.engineInit(genParamSpec, new SecureRandom()); } Initializes this parameter generator with a set of algorithm-specific parameter generation values. To generate the parameters, the `SecureRandom` implementation of the highest-priority installed provider is used as the source of randomness. (If none of the installed providers supply an implementation of `SecureRandom`, a system-provided source of randomness is used.)
public final void init(int size, SecureRandom random) { paramGenSpi.engineInit(size, random); } Initializes this parameter generator for a certain size and source of randomness.
public final void init(AlgorithmParameterSpec genParamSpec, SecureRandom random) throws InvalidAlgorithmParameterException { paramGenSpi.engineInit(genParamSpec, random); } Initializes this parameter generator with a set of algorithm-specific parameter generation values.

Method from java.security.AlgorithmParameterGenerator Detail:

 public final AlgorithmParameters generateParameters() {
        return paramGenSpi.engineGenerateParameters();
}

Generates the parameters.

 public final String getAlgorithm() {
        return this.algorithm;
}

Returns the standard name of the algorithm this parameter generator is associated with.

 public static AlgorithmParameterGenerator getInstance(String algorithm) throws NoSuchAlgorithmException {
            try {
                Object[] objs = Security.getImpl(algorithm,
                                                 "AlgorithmParameterGenerator",
                                                 (String)null);
                return new AlgorithmParameterGenerator
                    ((AlgorithmParameterGeneratorSpi)objs[0],
                     (Provider)objs[1],
                     algorithm);
            } catch(NoSuchProviderException e) {
                throw new NoSuchAlgorithmException(algorithm + " not found");
            }
}

This method traverses the list of registered security Providers, starting with the most preferred Provider. A new AlgorithmParameterGenerator object encapsulating the AlgorithmParameterGeneratorSpi implementation from the first Provider that supports the specified algorithm is returned.

Note that the list of registered providers may be retrieved via the Security.getProviders() method.

 public static AlgorithmParameterGenerator getInstance(String algorithm,
    String provider) throws NoSuchProviderException, NoSuchAlgorithmException {
        if (provider == null || provider.length() == 0)
            throw new IllegalArgumentException("missing provider");
        Object[] objs = Security.getImpl(algorithm,
                                         "AlgorithmParameterGenerator",
                                         provider);
        return new AlgorithmParameterGenerator
            ((AlgorithmParameterGeneratorSpi)objs[0], (Provider)objs[1],
             algorithm);
}

A new AlgorithmParameterGenerator object encapsulating the AlgorithmParameterGeneratorSpi implementation from the specified provider is returned. The specified provider must be registered in the security provider list.

Note that the list of registered providers may be retrieved via the Security.getProviders() method.

 public static AlgorithmParameterGenerator getInstance(String algorithm,
    Provider provider) throws NoSuchAlgorithmException {
        if (provider == null)
            throw new IllegalArgumentException("missing provider");
        Object[] objs = Security.getImpl(algorithm,
                                         "AlgorithmParameterGenerator",
                                         provider);
        return new AlgorithmParameterGenerator
            ((AlgorithmParameterGeneratorSpi)objs[0], (Provider)objs[1],
             algorithm);
}

A new AlgorithmParameterGenerator object encapsulating the AlgorithmParameterGeneratorSpi implementation from the specified Provider object is returned. Note that the specified Provider object does not have to be registered in the provider list.

 public final Provider getProvider() {
        return this.provider;
}

Returns the provider of this algorithm parameter generator object.

 public final  void init(int size) {
        paramGenSpi.engineInit(size, new SecureRandom());
}

SecureRandom

 public final  void init(AlgorithmParameterSpec genParamSpec) throws InvalidAlgorithmParameterException {
            paramGenSpi.engineInit(genParamSpec, new SecureRandom());
}

SecureRandom

 public final  void init(int size,
    SecureRandom random) {
        paramGenSpi.engineInit(size, random);
}

Initializes this parameter generator for a certain size and source of randomness.

 public final  void init(AlgorithmParameterSpec genParamSpec,
    SecureRandom random) throws InvalidAlgorithmParameterException {
            paramGenSpi.engineInit(genParamSpec, random);
}

Initializes this parameter generator with a set of algorithm-specific parameter generation values.