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java.security
Class AlgorithmParameters
java.lang.Object
java.security.AlgorithmParameters
-
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 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.
There are two ways to request such an implementation: by specifying either just an algorithm name, or both an algorithm name and a package provider.
-
If just an algorithm name is specified, the system will determine if there is an AlgorithmParameters implementation for the algorithm requested available in the environment, and if there is more than one, if there is a preferred one.
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If both an algorithm name and a package provider are specified, the system will determine if there is an implementation in the package requested, and throw an exception if there is not.
Once an AlgorithmParameters object is returned, 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.
-
Since:
-
1.2
-
See Also:
-
AlgorithmParameterSpec
,
DSAParameterSpec
,
KeyPairGenerator
Method Summary
|
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
Returns
Generates
a parameter object for the specified algorithm. |
static
AlgorithmParameters
|
getInstance
(
String
algorithm,
Provider
Returns
Generates
a parameter object for the specified
algorithm.
algorithm, as supplied by the specified provider, if such an algorithm is available from the provider.
|
static
AlgorithmParameters
|
getInstance
(
String
algorithm,
String
Returns
Generates
a parameter object for the specified
algorithm.
algorithm, as supplied by the specified provider, if such an algorithm is available from the provider.
|
<T extends
AlgorithmParameterSpec
>
T |
|
getParameterSpec
(
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 in paramSpec. |
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 from params and decodes them according to the specified decoding scheme. |
String
|
toString
()
Returns a formatted string describing the parameters. |
AlgorithmParameters
protected AlgorithmParameters(AlgorithmParametersSpi paramSpi,
Provider provider,
String algorithm)
-
Creates an AlgorithmParameters object.
-
Parameters:
-
paramSpi - the delegate
-
provider - the provider
-
algorithm - the algorithm
getAlgorithm
public final String getAlgorithm()
-
Returns the name of the algorithm associated with this parameter object.
-
-
Returns:
-
the algorithm name.
getInstance
public static AlgorithmParameters getInstance(String algorithm)
throws NoSuchAlgorithmException
-
Returns
Generates
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.
If the default provider package provides an implementation of the requested algorithm, an instance of AlgorithmParameters containing that implementation is returned. If the algorithm is not available in the default package, other packages are searched.
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 Appendix A in the
Java Cryptography Architecture API Specification & Reference
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
- if the algorithm is not available in the environment.
getInstance
public static AlgorithmParameters getInstance(String algorithm,
String provider)
throws NoSuchAlgorithmException,
NoSuchProviderException
-
Returns a parameter object for the specified algorithm.
Generates a parameter object for the specified algorithm, as supplied by the specified provider, if such an algorithm is available from the provider.
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 Appendix A in the
Java Cryptography Architecture API Specification & Reference
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
in
the
specified
package supplied by the requested
provider. -
NoSuchProviderException
- if the
specified
provider is not
registered
available
in the
security provider list.
environment.
-
IllegalArgumentException
- if the provider name is null or empty.
-
See Also:
-
Provider
getInstance
public static AlgorithmParameters getInstance(String algorithm,
Provider provider)
throws NoSuchAlgorithmException
-
Returns a parameter object for the specified algorithm.
Generates a parameter object for the specified algorithm, as supplied by the specified provider, if such an algorithm is available from the provider. Note: the provider doesn't have to be registered.
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 Appendix A in the
Java Cryptography Architecture API Specification & Reference
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
in
the
specified Provider object.
package supplied by the requested provider.
-
IllegalArgumentException
- if the provider is null.
-
Since:
-
1.4
-
See Also:
-
Provider
getProvider
public final Provider getProvider()
-
Returns the provider of this parameter object.
-
-
Returns:
-
the provider of this parameter object
init
public final void init(AlgorithmParameterSpec paramSpec)
throws InvalidParameterSpecException
-
Initializes this parameter object using the parameters specified in paramSpec.
-
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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.
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.
-
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Parameters:
-
params - the encoded parameters.
-
Throws:
-
IOException
- on decoding errors, or if this parameter object has already been initialized.
init
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.
-
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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.
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, be DSAParameterSpec.class, to indicate that the parameters should be returned in an instance of the DSAParameterSpec 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.
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.
getEncoded
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.
-
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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.
toString
public final String toString()
-
Returns a formatted string describing the parameters.
-
-
Overrides:
-
toString
in class
Object
-
-
Returns:
-
a formatted string describing the parameters, or null if this parameter object has not been initialized.