- java.lang.Object
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- java.security.AlgorithmParameters
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public class AlgorithmParameters extends Object
This class is used as an opaque representation of cryptographic parameters.An
AlgorithmParameters
object for managing the parameters for a particular algorithm can be obtained by calling one of thegetInstance
factory methods (static methods that return instances of a given class).Once an
AlgorithmParameters
object is obtained, it must be initialized via a call toinit
, using an appropriate parameter specification or parameter encoding.A transparent parameter specification is obtained from an
AlgorithmParameters
object via a call togetParameterSpec
, and a byte encoding of the parameters is obtained via a call togetEncoded
.Every implementation of the Java platform is required to support the following standard
AlgorithmParameters
algorithms:- AES
- DES
- DESede
- DiffieHellman
- DSA
- Since:
- 1.2
- See Also:
AlgorithmParameterSpec
,DSAParameterSpec
,KeyPairGenerator
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Constructor Summary
Constructors Modifier Constructor and Description protected
AlgorithmParameters(AlgorithmParametersSpi paramSpi, Provider provider, String algorithm)
Creates an AlgorithmParameters object.
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Method Summary
Methods Modifier and Type Method and Description String
getAlgorithm()
Returns the name of the algorithm associated with this parameter object.byte[]
getEncoded()
Returns the parameters in their primary encoding format.byte[]
getEncoded(String format)
Returns the parameters encoded in the specified scheme.static AlgorithmParameters
getInstance(String algorithm)
Returns a parameter object for the specified algorithm.static AlgorithmParameters
getInstance(String algorithm, Provider provider)
Returns a parameter object for the specified algorithm.static AlgorithmParameters
getInstance(String algorithm, String provider)
Returns a parameter object for the specified algorithm.<T extends AlgorithmParameterSpec>
TgetParameterSpec(Class<T> paramSpec)
Returns a (transparent) specification of this parameter object.Provider
getProvider()
Returns the provider of this parameter object.void
init(AlgorithmParameterSpec paramSpec)
Initializes this parameter object using the parameters specified inparamSpec
.void
init(byte[] params)
Imports the specified parameters and decodes them according to the primary decoding format for parameters.void
init(byte[] params, String format)
Imports the parameters fromparams
and decodes them according to the specified decoding scheme.String
toString()
Returns a formatted string describing the parameters.
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Constructor Detail
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AlgorithmParameters
protected AlgorithmParameters(AlgorithmParametersSpi paramSpi, Provider provider, String algorithm)
Creates an AlgorithmParameters object.- Parameters:
paramSpi
- the delegateprovider
- the provideralgorithm
- the algorithm
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Method Detail
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getAlgorithm
public final String getAlgorithm()
Returns the name of the algorithm associated with this parameter object.- Returns:
- the algorithm name.
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getInstance
public static AlgorithmParameters getInstance(String algorithm) throws NoSuchAlgorithmException
Returns a parameter object for the specified algorithm.This method traverses the list of registered security Providers, starting with the most preferred Provider. A new AlgorithmParameters object encapsulating the AlgorithmParametersSpi 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.The returned parameter object must be initialized via a call to
init
, using an appropriate parameter specification or parameter encoding.- Parameters:
algorithm
- the name of the algorithm requested. See the AlgorithmParameters section in the Java Cryptography Architecture Standard Algorithm Name Documentation for information about standard algorithm names.- Returns:
- the new parameter object.
- Throws:
NoSuchAlgorithmException
- if no Provider supports an AlgorithmParametersSpi implementation for the specified algorithm.- See Also:
Provider
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getInstance
public static AlgorithmParameters getInstance(String algorithm, String provider) throws NoSuchAlgorithmException, NoSuchProviderException
Returns a parameter object for the specified algorithm.A new AlgorithmParameters object encapsulating the AlgorithmParametersSpi 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.The returned parameter object must be initialized via a call to
init
, using an appropriate parameter specification or parameter encoding.- Parameters:
algorithm
- the name of the algorithm requested. See the AlgorithmParameters section in the Java Cryptography Architecture Standard Algorithm Name Documentation for information about standard algorithm names.provider
- the name of the provider.- Returns:
- the new parameter object.
- Throws:
NoSuchAlgorithmException
- if an AlgorithmParametersSpi 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.- See Also:
Provider
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getInstance
public static AlgorithmParameters getInstance(String algorithm, Provider provider) throws NoSuchAlgorithmException
Returns a parameter object for the specified algorithm.A new AlgorithmParameters object encapsulating the AlgorithmParametersSpi implementation from the specified Provider object is returned. Note that the specified Provider object does not have to be registered in the provider list.
The returned parameter object must be initialized via a call to
init
, using an appropriate parameter specification or parameter encoding.- Parameters:
algorithm
- the name of the algorithm requested. See the AlgorithmParameters section in the Java Cryptography Architecture Standard Algorithm Name Documentation for information about standard algorithm names.provider
- the name of the provider.- Returns:
- the new parameter object.
- Throws:
NoSuchAlgorithmException
- if an AlgorithmParameterGeneratorSpi implementation for the specified algorithm is not available from the specified Provider object.IllegalArgumentException
- if the provider is null.- Since:
- 1.4
- See Also:
Provider
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getProvider
public final Provider getProvider()
Returns the provider of this parameter object.- Returns:
- the provider of this parameter object
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init
public final void init(AlgorithmParameterSpec paramSpec) throws InvalidParameterSpecException
Initializes this parameter object using the parameters specified inparamSpec
.- Parameters:
paramSpec
- the parameter specification.- Throws:
InvalidParameterSpecException
- if the given parameter specification is inappropriate for the initialization of this parameter object, or if this parameter object has already been initialized.
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init
public final void init(byte[] params) throws IOException
Imports the specified parameters and decodes them according to the primary decoding format for parameters. The primary decoding format for parameters is ASN.1, if an ASN.1 specification for this type of parameters exists.- Parameters:
params
- the encoded parameters.- Throws:
IOException
- on decoding errors, or if this parameter object has already been initialized.
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init
public final void init(byte[] params, String format) throws IOException
Imports the parameters fromparams
and decodes them according to the specified decoding scheme. Ifformat
is null, the primary decoding format for parameters is used. The primary decoding format is ASN.1, if an ASN.1 specification for these parameters exists.- Parameters:
params
- the encoded parameters.format
- the name of the decoding scheme.- Throws:
IOException
- on decoding errors, or if this parameter object has already been initialized.
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getParameterSpec
public final <T extends AlgorithmParameterSpec> T getParameterSpec(Class<T> paramSpec) throws InvalidParameterSpecException
Returns a (transparent) specification of this parameter object.paramSpec
identifies the specification class in which the parameters should be returned. It could, for example, beDSAParameterSpec.class
, to indicate that the parameters should be returned in an instance of theDSAParameterSpec
class.- Parameters:
paramSpec
- the specification class in which the parameters should be returned.- Returns:
- the parameter specification.
- Throws:
InvalidParameterSpecException
- if the requested parameter specification is inappropriate for this parameter object, or if this parameter object has not been initialized.
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getEncoded
public final byte[] getEncoded() throws IOException
Returns the parameters in their primary encoding format. The primary encoding format for parameters is ASN.1, if an ASN.1 specification for this type of parameters exists.- Returns:
- the parameters encoded using their primary encoding format.
- Throws:
IOException
- on encoding errors, or if this parameter object has not been initialized.
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getEncoded
public final byte[] getEncoded(String format) throws IOException
Returns the parameters encoded in the specified scheme. Ifformat
is null, the primary encoding format for parameters is used. The primary encoding format is ASN.1, if an ASN.1 specification for these parameters exists.- Parameters:
format
- the name of the encoding format.- Returns:
- the parameters encoded using the specified encoding scheme.
- Throws:
IOException
- on encoding errors, or if this parameter object has not been initialized.
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