public class AlgorithmParameterGenerator extends Object
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:
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)Modifier | Constructor | Description |
---|---|---|
protected |
Creates an AlgorithmParameterGenerator object. |
Modifier and Type | Method | Description |
---|---|---|
final AlgorithmParameters |
generateParameters() |
Generates the parameters. |
final String |
getAlgorithm() |
Returns the standard name of the algorithm this parameter generator is associated with. |
static AlgorithmParameterGenerator |
getInstance |
Returns an AlgorithmParameterGenerator object for generating a set of parameters to be used with the specified algorithm. |
static AlgorithmParameterGenerator |
getInstance |
Returns an AlgorithmParameterGenerator object for generating a set of parameters to be used with the specified algorithm. |
static AlgorithmParameterGenerator |
getInstance |
Returns an AlgorithmParameterGenerator object for generating a set of parameters to be used with the specified algorithm. |
final Provider |
getProvider() |
Returns the provider of this algorithm parameter generator object. |
final void |
init |
Initializes this parameter generator for a certain size. |
final void |
init |
Initializes this parameter generator for a certain size and source of randomness. |
final void |
init |
Initializes this parameter generator with a set of algorithm-specific parameter generation values. |
final void |
init |
Initializes this parameter generator with a set of algorithm-specific parameter generation values. |
protected AlgorithmParameterGenerator(AlgorithmParameterGeneratorSpi paramGenSpi, Provider provider, String algorithm)
AlgorithmParameterGenerator
object.paramGenSpi
- the delegateprovider
- the provideralgorithm
- the algorithmpublic final String getAlgorithm()
public static AlgorithmParameterGenerator getInstance(String algorithm) throws NoSuchAlgorithmException
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.
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()
.algorithm
- 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.AlgorithmParameterGenerator
objectNoSuchAlgorithmException
- if no Provider
supports an AlgorithmParameterGeneratorSpi
implementation for the specified algorithmNullPointerException
- if algorithm
is null
public static AlgorithmParameterGenerator getInstance(String algorithm, String provider) throws NoSuchAlgorithmException, NoSuchProviderException
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.
algorithm
- 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
- the string name of the Provider
.AlgorithmParameterGenerator
objectIllegalArgumentException
- if the provider name is null
or emptyNoSuchAlgorithmException
- if an AlgorithmParameterGeneratorSpi
implementation for the specified algorithm is not available from the specified providerNoSuchProviderException
- if the specified provider is not registered in the security provider listNullPointerException
- if algorithm
is null
public static AlgorithmParameterGenerator getInstance(String algorithm, Provider provider) throws NoSuchAlgorithmException
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.
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 for information about standard algorithm names.provider
- the Provider
object.AlgorithmParameterGenerator
objectIllegalArgumentException
- if the specified provider is null
NoSuchAlgorithmException
- if an AlgorithmParameterGeneratorSpi
implementation for the specified algorithm is not available from the specified Provider
objectNullPointerException
- if algorithm
is null
public final Provider getProvider()
public final void init(int size)
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.)size
- the size (number of bits).public final void init(int size, SecureRandom random)
size
- the size (number of bits).random
- the source of randomness.public final void init(AlgorithmParameterSpec genParamSpec) throws InvalidAlgorithmParameterException
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.)genParamSpec
- the set of algorithm-specific parameter generation values.InvalidAlgorithmParameterException
- if the given parameter generation values are inappropriate for this parameter generator.public final void init(AlgorithmParameterSpec genParamSpec, SecureRandom random) throws InvalidAlgorithmParameterException
genParamSpec
- the set of algorithm-specific parameter generation values.random
- the source of randomness.InvalidAlgorithmParameterException
- if the given parameter generation values are inappropriate for this parameter generator.public final AlgorithmParameters generateParameters()
AlgorithmParameters
object.
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