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.
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:
AES
DES
DESede
DiffieHellman
DSA
- Since:
- 1.2
- See Also:
-
AlgorithmParameterSpec
,DSAParameterSpec
,KeyPairGenerator
Constructor Summary
Modifier | Constructor | Description |
---|---|---|
protected | AlgorithmParameters(AlgorithmParametersSpi paramSpi,
Provider provider,
String algorithm) | Creates an AlgorithmParameters object. |
Method Summary
Modifier and Type | Method | 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,
String provider) | Returns a parameter object for the specified algorithm. |
static AlgorithmParameters | getInstance(String algorithm,
Provider provider) | Returns a parameter object for the specified algorithm. |
<T extends AlgorithmParameterSpec> | getParameterSpec(Class<T> paramSpec) | Returns a (transparent) specification of this parameter object. |
Provider | getProvider() | Returns the provider of this parameter object. |
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 |
void | init(AlgorithmParameterSpec paramSpec) | Initializes this parameter object using the parameters specified in |
String | toString() | Returns a formatted string describing the parameters. |
Methods declared in class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
Constructor Detail
AlgorithmParameters
protected AlgorithmParameters(AlgorithmParametersSpi paramSpi, Provider provider, String algorithm)
Creates an AlgorithmParameters object.
- Parameters:
-
paramSpi
- the delegate -
provider
- the provider -
algorithm
- the algorithm
Method Detail
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 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 than the order of providers returned bySecurity.getProviders()
. - Parameters:
-
algorithm
- 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:
- the new parameter object
- Throws:
-
NoSuchAlgorithmException
- if noProvider
supports anAlgorithmParametersSpi
implementation for the specified algorithm -
NullPointerException
- ifalgorithm
isnull
- See Also:
Provider
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 Security Standard Algorithm Names Specification for information about standard algorithm names. -
provider
- the name of the provider. - Returns:
- the new parameter object
- Throws:
-
IllegalArgumentException
- if the provider name isnull
or empty -
NoSuchAlgorithmException
- if anAlgorithmParametersSpi
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 -
NullPointerException
- ifalgorithm
isnull
- See Also:
Provider
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 Security Standard Algorithm Names Specification for information about standard algorithm names. -
provider
- the name of the provider. - Returns:
- the new parameter object
- Throws:
-
IllegalArgumentException
- if the provider isnull
-
NoSuchAlgorithmException
- if anAlgorithmParameterGeneratorSpi
implementation for the specified algorithm is not available from the specifiedProvider
object -
NullPointerException
- ifalgorithm
isnull
- 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
.
- 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.
- 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.
- 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.
- Type Parameters:
-
T
- the type of the parameter specification to be returrned - 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.
- 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.