OpenJDK 1.22 · 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. See the Keysize Restriction sections of the JDK 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.

Modifier and Type	Field and Description
private final String	algorithm
private final AlgorithmParameterGeneratorSpi	paramGenSpi
private final Provider	provider

Access	Constructor and Description
protected	AlgorithmParameterGenerator(AlgorithmParameterGeneratorSpi the delegate paramGenSpi, Provider the provider provider, String the algorithm algorithm) Creates an `AlgorithmParameterGenerator` object.

Method Summary

Modifier and Type	Method and Description
public final AlgorithmParameters	Returns: the new `AlgorithmParameters` object. generateParameters() Generates the parameters.
public final String	Returns: the string name of the algorithm. getAlgorithm() Returns the standard name of the algorithm this parameter generator is associated with.
public static AlgorithmParameterGenerator	Returns: the new `AlgorithmParameterGenerator` object getInstance(String the name of the algorithm this parameter generator is associated with. See the AlgorithmParameterGenerator section in the Java Security Standard Algorithm Names Specification for information about standard algorithm names. algorithm) Returns an `AlgorithmParameterGenerator` object for generating a set of parameters to be used with the specified algorithm.
public static AlgorithmParameterGenerator	Returns: the new `AlgorithmParameterGenerator` object getInstance(String the name of the algorithm this parameter generator is associated with. See the AlgorithmParameterGenerator section in the Java Security Standard Algorithm Names Specification for information about standard algorithm names. algorithm, String the string name of the `Provider`. provider) Returns an `AlgorithmParameterGenerator` object for generating a set of parameters to be used with the specified algorithm.
public static AlgorithmParameterGenerator	Returns: the new `AlgorithmParameterGenerator` object getInstance(String the string name of the algorithm this parameter generator is associated with. See the AlgorithmParameterGenerator section in the Java Security Standard Algorithm Names Specification for information about standard algorithm names. algorithm, Provider the `Provider` object. provider) Returns an `AlgorithmParameterGenerator` object for generating a set of parameters to be used with the specified algorithm.
public final Provider	Returns: the provider of this algorithm parameter generator object getProvider() Returns the provider of this algorithm parameter generator object.
public final void	init(int the size (number of bits). size) Initializes this parameter generator for a certain size.
public final void	init(int the size (number of bits). size, SecureRandom the source of randomness. random) Initializes this parameter generator for a certain size and source of randomness.
public final void	init(AlgorithmParameterSpec the set of algorithm-specific parameter generation values. genParamSpec) Initializes this parameter generator with a set of algorithm-specific parameter generation values.
public final void	init(AlgorithmParameterSpec the set of algorithm-specific parameter generation values. genParamSpec, SecureRandom the source of randomness. random) Initializes this parameter generator with a set of algorithm-specific parameter generation values.

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

Field Detail

algorithm	back to summary
private final String algorithm

paramGenSpi	back to summary
private final AlgorithmParameterGeneratorSpi paramGenSpi

provider	back to summary
private final Provider provider

Constructor Detail

AlgorithmParameterGenerator back to summary

AlgorithmParameterGenerator	back to summary
protected AlgorithmParameterGenerator(AlgorithmParameterGeneratorSpi paramGenSpi, Provider provider, String algorithm) Creates an `AlgorithmParameterGenerator` object. Parameters paramGenSpi:AlgorithmParameterGeneratorSpi the delegate provider:Provider the provider algorithm:String the algorithm

protected AlgorithmParameterGenerator(AlgorithmParameterGeneratorSpi paramGenSpi, Provider provider, String algorithm)

Creates an AlgorithmParameterGenerator object.

Parameters

paramGenSpi:AlgorithmParameterGeneratorSpi: the delegate
provider:Provider: the provider
algorithm:String: the algorithm

Method Detail

generateParameters back to summary

generateParameters	back to summary
public final AlgorithmParameters generateParameters() Generates the parameters. Returns:AlgorithmParameters the new `AlgorithmParameters` object.

public final AlgorithmParameters generateParameters()

Generates the parameters.

Returns:AlgorithmParameters: the new AlgorithmParameters object.

getAlgorithm	back to summary
public final String getAlgorithm() Returns the standard name of the algorithm this parameter generator is associated with. Returns:String the string name of the algorithm.

getAlgorithm

back to summary

public final String getAlgorithm()

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

Returns:String: the string name of the algorithm.

getInstance back to summary

getInstance	back to summary
public static AlgorithmParameterGenerator getInstance(String algorithm) throws NoSuchAlgorithmException 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. Implementation Note The JDK Reference Implementation additionally uses the `jdk.security.provider.preferred` `Security` property to determine the preferred provider order for the specified algorithm. This may be different from the order of providers returned by `Security.getProviders()`. Parameters algorithm:String the name of the algorithm this parameter generator is associated with. See the AlgorithmParameterGenerator section in the Java Security Standard Algorithm Names Specification for information about standard algorithm names. Returns:AlgorithmParameterGenerator the new `AlgorithmParameterGenerator` object Exceptions NoSuchAlgorithmException: if no `Provider` supports an `AlgorithmParameterGeneratorSpi` implementation for the specified algorithm NullPointerException: if `algorithm` is `null` See Also `Provider`

public static AlgorithmParameterGenerator getInstance(String algorithm) throws NoSuchAlgorithmException

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.

Implementation Note

The JDK Reference Implementation additionally uses the jdk.security.provider.preferred Security property to determine the preferred provider order for the specified algorithm. This may be different from the order of providers returned by Security.getProviders().

Parameters

algorithm:String: the name of the algorithm this parameter generator is associated with. See the AlgorithmParameterGenerator section in the Java Security Standard Algorithm Names Specification for information about standard algorithm names.

Returns:AlgorithmParameterGenerator

the new AlgorithmParameterGenerator object

Exceptions

NoSuchAlgorithmException:: if no Provider supports an AlgorithmParameterGeneratorSpi implementation for the specified algorithm
NullPointerException:: if algorithm is null

See Also

Provider

getInstance back to summary

getInstance	back to summary
public static AlgorithmParameterGenerator getInstance(String algorithm, String provider) throws NoSuchAlgorithmException, NoSuchProviderException 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. Parameters algorithm:String the name of the algorithm this parameter generator is associated with. See the AlgorithmParameterGenerator section in the Java Security Standard Algorithm Names Specification for information about standard algorithm names. provider:String the string name of the `Provider`. Returns:AlgorithmParameterGenerator the new `AlgorithmParameterGenerator` object Exceptions NoSuchAlgorithmException: if an `AlgorithmParameterGeneratorSpi` implementation for the specified algorithm is not available from the specified provider NoSuchProviderException: if the specified provider is not registered in the security provider list IllegalArgumentException: if the provider name is `null` or empty NullPointerException: if `algorithm` is `null` See Also `Provider`

public static AlgorithmParameterGenerator getInstance(String algorithm, String provider) throws NoSuchAlgorithmException, NoSuchProviderException

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.

Parameters

algorithm:String: the name of the algorithm this parameter generator is associated with. See the AlgorithmParameterGenerator section in the Java Security Standard Algorithm Names Specification for information about standard algorithm names.
provider:String: the string name of the Provider.

Returns:AlgorithmParameterGenerator

the new AlgorithmParameterGenerator object

Exceptions

NoSuchAlgorithmException:: if an AlgorithmParameterGeneratorSpi implementation for the specified algorithm is not available from the specified provider
NoSuchProviderException:: if the specified provider is not registered in the security provider list
IllegalArgumentException:: if the provider name is null or empty
NullPointerException:: if algorithm is null

See Also

Provider

getInstance back to summary

getInstance	back to summary
public static AlgorithmParameterGenerator getInstance(String algorithm, Provider provider) throws NoSuchAlgorithmException 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. Note that the specified provider does not have to be registered in the provider list. Parameters algorithm:String the string name of the algorithm this parameter generator is associated with. See the AlgorithmParameterGenerator section in the Java Security Standard Algorithm Names Specification for information about standard algorithm names. provider:Provider the `Provider` object. Returns:AlgorithmParameterGenerator the new `AlgorithmParameterGenerator` object Exceptions NoSuchAlgorithmException: if an `AlgorithmParameterGeneratorSpi` implementation for the specified algorithm is not available from the specified `Provider` object IllegalArgumentException: if the specified provider is `null` NullPointerException: if `algorithm` is `null` Since 1.4 See Also `Provider`

public static AlgorithmParameterGenerator getInstance(String algorithm, Provider provider) throws NoSuchAlgorithmException

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. Note that the specified provider does not have to be registered in the provider list.

Parameters

algorithm:String: the string name of the algorithm this parameter generator is associated with. See the AlgorithmParameterGenerator section in the Java Security Standard Algorithm Names Specification for information about standard algorithm names.
provider:Provider: the Provider object.

Returns:AlgorithmParameterGenerator

the new AlgorithmParameterGenerator object

Exceptions

NoSuchAlgorithmException:: if an AlgorithmParameterGeneratorSpi implementation for the specified algorithm is not available from the specified Provider object
IllegalArgumentException:: if the specified provider is null
NullPointerException:: if algorithm is null

Since

1.4

See Also

Provider

getProvider	back to summary
public final Provider getProvider() Returns the provider of this algorithm parameter generator object. Returns:Provider the provider of this algorithm parameter generator object

getProvider

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public final Provider getProvider()

Returns the provider of this algorithm parameter generator object.

Returns:Provider: the provider of this algorithm parameter generator object

init back to summary

init	back to summary
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:int the size (number of bits).

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:int: the size (number of bits).

init	back to summary
public final void init(int size, SecureRandom random) Initializes this parameter generator for a certain size and source of randomness. Parameters size:int the size (number of bits). random:SecureRandom the source of randomness.

init

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public final void init(int size, SecureRandom random)

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

Parameters

size:int: the size (number of bits).
random:SecureRandom: the source of randomness.

init back to summary

init	back to summary
public final void init(AlgorithmParameterSpec genParamSpec) throws InvalidAlgorithmParameterException 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:AlgorithmParameterSpec the set of algorithm-specific parameter generation values. Exceptions InvalidAlgorithmParameterException: if the given parameter generation values are inappropriate for this parameter generator.

public final void init(AlgorithmParameterSpec genParamSpec) throws InvalidAlgorithmParameterException

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:AlgorithmParameterSpec: the set of algorithm-specific parameter generation values.

Exceptions

InvalidAlgorithmParameterException:: if the given parameter generation values are inappropriate for this parameter generator.

init	back to summary
public final void init(AlgorithmParameterSpec genParamSpec, SecureRandom random) throws InvalidAlgorithmParameterException Initializes this parameter generator with a set of algorithm-specific parameter generation values. Parameters genParamSpec:AlgorithmParameterSpec the set of algorithm-specific parameter generation values. random:SecureRandom the source of randomness. Exceptions InvalidAlgorithmParameterException: if the given parameter generation values are inappropriate for this parameter generator.

init

back to summary

public final void init(AlgorithmParameterSpec genParamSpec, SecureRandom random) throws InvalidAlgorithmParameterException

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

Parameters

genParamSpec:AlgorithmParameterSpec: the set of algorithm-specific parameter generation values.
random:SecureRandom: the source of randomness.

Exceptions

InvalidAlgorithmParameterException:: if the given parameter generation values are inappropriate for this parameter generator.

public Class AlgorithmParameterGenerator

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