AlgorithmParameterGenerator (Java SE 9 & JDK 9 ) (original) (raw)

java.lang.Object
- java.security.AlgorithmParameterGenerator

public class AlgorithmParameterGenerator
extends Object
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. See the Keysize Restriction sections of theJDK Providers document for information on the AlgorithmParameterGenerator defaults used by JDK providers. However, note that defaults may vary across different providers. Additionally, the default value for a provider may change in a future version. Therefore, it is recommended to explicitly initialize the AlgorithmParameterGenerator instead of relying on provider-specific defaults.
Every implementation of the Java platform is required to support the following standard AlgorithmParameterGenerator algorithms and keysizes in parentheses:
DiffieHellman (1024, 2048)
DSA (1024, 2048)
These algorithms are described in the AlgorithmParameterGenerator section of the Java Security Standard Algorithm Names Specification. Consult the release documentation for your implementation to see if any other algorithms are supported.
Since:
1.2
See Also:
AlgorithmParameters, AlgorithmParameterSpec

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	AlgorithmParameterGenerator(AlgorithmParameterGeneratorSpi paramGenSpi,Provider provider,String algorithm)	Creates an AlgorithmParameterGenerator object.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods

Modifier and Type	Method	Description
AlgorithmParameters	generateParameters()	Generates the parameters.
String	getAlgorithm()	Returns the standard name of the algorithm this parameter generator is associated with.
static AlgorithmParameterGenerator	getInstance(String algorithm)	Returns an AlgorithmParameterGenerator object for generating a set of parameters to be used with the specified algorithm.
static AlgorithmParameterGenerator	getInstance(String algorithm,String provider)	Returns an AlgorithmParameterGenerator object for generating a set of parameters to be used with the specified algorithm.
static AlgorithmParameterGenerator	getInstance(String algorithm,Provider provider)	Returns an AlgorithmParameterGenerator object for generating a set of parameters to be used with the specified algorithm.
Provider	getProvider()	Returns the provider of this algorithm parameter generator object.
void	init(int size)	Initializes this parameter generator for a certain size.
void	init(int size,SecureRandom random)	Initializes this parameter generator for a certain size and source of randomness.
void	init(AlgorithmParameterSpec genParamSpec)	Initializes this parameter generator with a set of algorithm-specific parameter generation values.
void	init(AlgorithmParameterSpec genParamSpec,SecureRandom random)	Initializes this parameter generator with a set of algorithm-specific parameter generation values.

   * ### Methods inherited from class java.lang.[Object](../../java/lang/Object.html "class in java.lang")  
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Constructor Detail

 * #### AlgorithmParameterGenerator  
 protected AlgorithmParameterGenerator([AlgorithmParameterGeneratorSpi](../../java/security/AlgorithmParameterGeneratorSpi.html "class in java.security") paramGenSpi,  
                                       [Provider](../../java/security/Provider.html "class in java.security") provider,  
                                       [String](../../java/lang/String.html "class in java.lang") algorithm)  
 Creates an AlgorithmParameterGenerator object.  
 Parameters:  
 `paramGenSpi` \- the delegate  
 `provider` \- the provider  
 `algorithm` \- the algorithm

Method Detail

* #### getAlgorithm  
public final [String](../../java/lang/String.html "class in java.lang") getAlgorithm()  
Returns the standard name of the algorithm this parameter generator is associated with.  
Returns:  
the string name of the algorithm.  
* #### getInstance  
public static [AlgorithmParameterGenerator](../../java/security/AlgorithmParameterGenerator.html "class in java.security") getInstance([String](../../java/lang/String.html "class in java.lang") algorithm)  
                                               throws [NoSuchAlgorithmException](../../java/security/NoSuchAlgorithmException.html "class in java.security")  
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()](../../java/security/Security.html#getProviders--) method.  
Implementation Note:  
The JDK Reference Implementation additionally uses the`jdk.security.provider.preferred` [Security](../../java/security/Security.html#getProperty-java.lang.String-) property to determine the preferred provider order for the specified algorithm. This may be different than the order of providers returned by[Security.getProviders()](../../java/security/Security.html#getProviders--).  
Parameters:  
`algorithm` \- the name of the algorithm this parameter generator is associated with. See the AlgorithmParameterGenerator section in the [ Java Security Standard Algorithm Names Specification](../../../specs/security/standard-names.html#algorithmparametergenerator-algorithms) for information about standard algorithm names.  
Returns:  
the new `AlgorithmParameterGenerator` object  
Throws:  
`[NoSuchAlgorithmException](../../java/security/NoSuchAlgorithmException.html "class in java.security")` \- if no `Provider` supports an`AlgorithmParameterGeneratorSpi` implementation for the specified algorithm  
`[NullPointerException](../../java/lang/NullPointerException.html "class in java.lang")` \- if `algorithm` is `null`  
See Also:  
[Provider](../../java/security/Provider.html "class in java.security")  
* #### getInstance  
public static [AlgorithmParameterGenerator](../../java/security/AlgorithmParameterGenerator.html "class in java.security") getInstance([String](../../java/lang/String.html "class in java.lang") algorithm,  
                                                      [String](../../java/lang/String.html "class in java.lang") provider)  
                                               throws [NoSuchAlgorithmException](../../java/security/NoSuchAlgorithmException.html "class in java.security"),  
                                                      [NoSuchProviderException](../../java/security/NoSuchProviderException.html "class in java.security")  
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()](../../java/security/Security.html#getProviders--) method.  
Parameters:  
`algorithm` \- the name of the algorithm this parameter generator is associated with. See the AlgorithmParameterGenerator section in the [ Java Security Standard Algorithm Names Specification](../../../specs/security/standard-names.html#algorithmparametergenerator-algorithms) for information about standard algorithm names.  
`provider` \- the string name of the Provider.  
Returns:  
the new `AlgorithmParameterGenerator` object  
Throws:  
`[IllegalArgumentException](../../java/lang/IllegalArgumentException.html "class in java.lang")` \- if the provider name is `null` or empty  
`[NoSuchAlgorithmException](../../java/security/NoSuchAlgorithmException.html "class in java.security")` \- if an`AlgorithmParameterGeneratorSpi` implementation for the specified algorithm is not available from the specified provider  
`[NoSuchProviderException](../../java/security/NoSuchProviderException.html "class in java.security")` \- if the specified provider is not registered in the security provider list  
`[NullPointerException](../../java/lang/NullPointerException.html "class in java.lang")` \- if `algorithm` is `null`  
See Also:  
[Provider](../../java/security/Provider.html "class in java.security")  
* #### getInstance  
public static [AlgorithmParameterGenerator](../../java/security/AlgorithmParameterGenerator.html "class in java.security") getInstance([String](../../java/lang/String.html "class in java.lang") algorithm,  
                                                      [Provider](../../java/security/Provider.html "class in java.security") provider)  
                                               throws [NoSuchAlgorithmException](../../java/security/NoSuchAlgorithmException.html "class in java.security")  
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.  
Parameters:  
`algorithm` \- the string name of the algorithm this parameter generator is associated with. See the AlgorithmParameterGenerator section in the [ Java Security Standard Algorithm Names Specification](../../../specs/security/standard-names.html#algorithmparametergenerator-algorithms) for information about standard algorithm names.  
`provider` \- the `Provider` object.  
Returns:  
the new `AlgorithmParameterGenerator` object  
Throws:  
`[IllegalArgumentException](../../java/lang/IllegalArgumentException.html "class in java.lang")` \- if the specified provider is`null`  
`[NoSuchAlgorithmException](../../java/security/NoSuchAlgorithmException.html "class in java.security")` \- if an`AlgorithmParameterGeneratorSpi` implementation for the specified algorithm is not available from the specified `Provider` object  
`[NullPointerException](../../java/lang/NullPointerException.html "class in java.lang")` \- if `algorithm` is `null`  
Since:  
1.4  
See Also:  
[Provider](../../java/security/Provider.html "class in java.security")  
* #### getProvider  
public final [Provider](../../java/security/Provider.html "class in java.security") getProvider()  
Returns the provider of this algorithm parameter generator object.  
Returns:  
the provider of this algorithm parameter generator object  
* #### init  
public final void init(int size)  
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.)  
Parameters:  
`size` \- the size (number of bits).  
* #### init  
public final void init(int size,  
                       [SecureRandom](../../java/security/SecureRandom.html "class in java.security") random)  
Initializes this parameter generator for a certain size and source of randomness.  
Parameters:  
`size` \- the size (number of bits).  
`random` \- the source of randomness.  
* #### init  
public final void init([AlgorithmParameterSpec](../../java/security/spec/AlgorithmParameterSpec.html "interface in java.security.spec") genParamSpec)  
                throws [InvalidAlgorithmParameterException](../../java/security/InvalidAlgorithmParameterException.html "class in java.security")  
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.)  
Parameters:  
`genParamSpec` \- the set of algorithm-specific parameter generation values.  
Throws:  
`[InvalidAlgorithmParameterException](../../java/security/InvalidAlgorithmParameterException.html "class in java.security")` \- if the given parameter generation values are inappropriate for this parameter generator.  
* #### init  
public final void init([AlgorithmParameterSpec](../../java/security/spec/AlgorithmParameterSpec.html "interface in java.security.spec") genParamSpec,  
                       [SecureRandom](../../java/security/SecureRandom.html "class in java.security") random)  
                throws [InvalidAlgorithmParameterException](../../java/security/InvalidAlgorithmParameterException.html "class in java.security")  
Initializes this parameter generator with a set of algorithm-specific parameter generation values.  
Parameters:  
`genParamSpec` \- the set of algorithm-specific parameter generation values.  
`random` \- the source of randomness.  
Throws:  
`[InvalidAlgorithmParameterException](../../java/security/InvalidAlgorithmParameterException.html "class in java.security")` \- if the given parameter generation values are inappropriate for this parameter generator.  
* #### generateParameters  
public final [AlgorithmParameters](../../java/security/AlgorithmParameters.html "class in java.security") generateParameters()  
Generates the parameters.  
Returns:  
the new AlgorithmParameters object.

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AlgorithmParameterGenerator (Java SE 9 & JDK 9 ) (original) (raw)

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