Top Description Fields Constructors Methods
java.security

public Class AlgorithmParameters

extends Object
Class Inheritance
Imports
java.io.*, java.security.spec.AlgorithmParameterSpec, .InvalidParameterSpecException, java.util.Objects
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 the getInstance factory methods (static methods that return instances of a given class).

Once an AlgorithmParameters object is obtained, it must be initialized via a call to init, using an appropriate parameter specification or parameter encoding.

A transparent parameter specification is obtained from an AlgorithmParameters object via a call to getParameterSpec, and a byte encoding of the parameters is obtained via a call to getEncoded.

Every implementation of the Java platform is required to support the following standard AlgorithmParameters algorithms:

These algorithms are described in the AlgorithmParameters section of the Java Security Standard Algorithm Names Specification. Consult the release documentation for your implementation to see if any other algorithms are supported.
Author
Jan Luehe
Since
1.2
See Also
java.security.spec.AlgorithmParameterSpec, java.security.spec.DSAParameterSpec, KeyPairGenerator

Field Summary

Modifier and TypeField and Description
private final String
algorithm

private boolean
initialized

private final AlgorithmParametersSpi
paramSpi

private final Provider
provider

Constructor Summary

AccessConstructor and Description
protected
AlgorithmParameters(AlgorithmParametersSpi
the delegate
paramSpi, Provider
the provider
provider, String
the algorithm
algorithm)

Creates an AlgorithmParameters object.

Method Summary

Modifier and TypeMethod and Description
public final String

Returns:

the algorithm name.
getAlgorithm()

Returns the name of the algorithm associated with this parameter object.

public final byte[]

Returns:

the parameters encoded using their primary encoding format.
getEncoded()

Returns the parameters in their primary encoding format.

public final byte[]

Returns:

the parameters encoded using the specified encoding scheme.
getEncoded(String
the name of the encoding format.
format)

Returns the parameters encoded in the specified scheme.

public static AlgorithmParameters

Returns:

the new parameter object
getInstance(String
the name of the algorithm requested. See the AlgorithmParameters section in the Java Security Standard Algorithm Names Specification for information about standard algorithm names.
algorithm)

Returns a parameter object for the specified algorithm.

public static AlgorithmParameters

Returns:

the new parameter object
getInstance(String
the name of the algorithm requested. See the AlgorithmParameters section in the Java Security Standard Algorithm Names Specification for information about standard algorithm names.
algorithm, String
the name of the provider.
provider)

Returns a parameter object for the specified algorithm.

public static AlgorithmParameters

Returns:

the new parameter object
getInstance(String
the name of the algorithm requested. See the AlgorithmParameters section in the Java Security Standard Algorithm Names Specification for information about standard algorithm names.
algorithm, Provider
the name of the provider.
provider)

Returns a parameter object for the specified algorithm.

public final <
the type of the parameter specification to be returned
T extends AlgorithmParameterSpec> T

Returns:

the parameter specification.
getParameterSpec(Class<T>
the specification class in which the parameters should be returned.
paramSpec)

Returns a (transparent) specification of this parameter object.

public final Provider

Returns:

the provider of this parameter object
getProvider()

Returns the provider of this parameter object.

public final void
init(AlgorithmParameterSpec
the parameter specification.
paramSpec)

Initializes this parameter object using the parameters specified in paramSpec.

public final void
init(byte[]
the encoded parameters.
params)

Imports the specified parameters and decodes them according to the primary decoding format for parameters.

public final void
init(byte[]
the encoded parameters.
params, String
the name of the decoding scheme.
format)

Imports the parameters from params and decodes them according to the specified decoding scheme.

public final String

Returns:

a formatted string describing the parameters, or null if this parameter object has not been initialized.
toString()

Overrides java.lang.Object.toString.

Returns a formatted string describing the parameters.

Inherited from java.lang.Object:
cloneequalsfinalizegetClasshashCodenotifynotifyAllwaitwaitwait

Field Detail

algorithmback to summary
private final String algorithm
initializedback to summary
private boolean initialized
paramSpiback to summary
private final AlgorithmParametersSpi paramSpi
providerback to summary
private final Provider provider

Constructor Detail

AlgorithmParametersback to summary
protected AlgorithmParameters(AlgorithmParametersSpi paramSpi, Provider provider, String algorithm)

Creates an AlgorithmParameters object.

Parameters
paramSpi:AlgorithmParametersSpi

the delegate

provider:Provider

the provider

algorithm:String

the algorithm

Method Detail

getAlgorithmback to summary
public final String getAlgorithm()

Returns the name of the algorithm associated with this parameter object.

Returns:String

the algorithm name.

getEncodedback to summary
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:byte[]

the parameters encoded using their primary encoding format.

Exceptions
IOException:
on encoding errors, or if this parameter object has not been initialized.
getEncodedback to summary
public final byte[] getEncoded(String format) throws IOException

Returns the parameters encoded in the specified scheme. If format 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:String

the name of the encoding format.

Returns:byte[]

the parameters encoded using the specified encoding scheme.

Exceptions
IOException:
on encoding errors, or if this parameter object has not been initialized.
getInstanceback to summary
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.

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 requested. See the AlgorithmParameters section in the Java Security Standard Algorithm Names Specification for information about standard algorithm names.

Returns:AlgorithmParameters

the new parameter object

Exceptions
NoSuchAlgorithmException:
if no Provider supports an AlgorithmParametersSpi implementation for the specified algorithm
NullPointerException:
if algorithm is null
See Also
Provider
getInstanceback to summary
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:String

the name of the algorithm requested. See the AlgorithmParameters section in the Java Security Standard Algorithm Names Specification for information about standard algorithm names.

provider:String

the name of the provider.

Returns:AlgorithmParameters

the new parameter object

Exceptions
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
NullPointerException:
if algorithm is null
See Also
Provider
getInstanceback to summary
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 is returned. Note that the specified provider 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:String

the name of the algorithm requested. See the AlgorithmParameters section in the Java Security Standard Algorithm Names Specification for information about standard algorithm names.

provider:Provider

the name of the provider.

Returns:AlgorithmParameters

the new parameter object

Exceptions
NoSuchAlgorithmException:
if an AlgorithmParameterGeneratorSpi implementation for the specified algorithm is not available from the specified Provider object
IllegalArgumentException:
if the provider is null
NullPointerException:
if algorithm is null
Since
1.4
See Also
Provider
getParameterSpecback to summary
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, be DSAParameterSpec.class, to indicate that the parameters should be returned in an instance of the DSAParameterSpec class.

Parameters
<T>
the type of the parameter specification to be returned
paramSpec:Class<T>

the specification class in which the parameters should be returned.

Returns:T

the parameter specification.

Exceptions
InvalidParameterSpecException:
if the requested parameter specification is inappropriate for this parameter object, or if this parameter object has not been initialized.
getProviderback to summary
public final Provider getProvider()

Returns the provider of this parameter object.

Returns:Provider

the provider of this parameter object

initback to summary
public final void init(AlgorithmParameterSpec paramSpec) throws InvalidParameterSpecException

Initializes this parameter object using the parameters specified in paramSpec.

Parameters
paramSpec:AlgorithmParameterSpec

the parameter specification.

Exceptions
InvalidParameterSpecException:
if the given parameter specification is inappropriate for the initialization of this parameter object, or if this parameter object has already been initialized.
initback to summary
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:byte[]

the encoded parameters.

Exceptions
IOException:
on decoding errors, or if this parameter object has already been initialized.
initback to summary
public final void init(byte[] params, String format) throws IOException

Imports the parameters from params and decodes them according to the specified decoding scheme. If format 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:byte[]

the encoded parameters.

format:String

the name of the decoding scheme.

Exceptions
IOException:
on decoding errors, or if this parameter object has already been initialized.
toStringback to summary
public final String toString()

Overrides java.lang.Object.toString.

Returns a formatted string describing the parameters.

Returns:String

a formatted string describing the parameters, or null if this parameter object has not been initialized.