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package java.security;
import java.io.*;
import java.security.spec.AlgorithmParameterSpec;
import java.security.spec.InvalidParameterSpecException;
import java.util.Objects;
/**
* This class is used as an opaque representation of cryptographic parameters.
*
* An {@code AlgorithmParameters} object for managing the parameters
* for a particular algorithm can be obtained by
* calling one of the {@code getInstance} factory methods
* (static methods that return instances of a given class).
*
*
Once an {@code AlgorithmParameters} object is obtained, it must be
* initialized via a call to {@code init}, using an appropriate parameter
* specification or parameter encoding.
*
*
A transparent parameter specification is obtained from an
* {@code AlgorithmParameters} object via a call to
* {@code getParameterSpec}, and a byte encoding of the parameters is
* obtained via a call to {@code getEncoded}.
*
*
Every implementation of the Java platform is required to support the
* following standard {@code AlgorithmParameters} algorithms:
*
* - {@code AES}
* - {@code DESede}
* - {@code DiffieHellman}
* - {@code DSA}
*
* 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
*
*
* @see java.security.spec.AlgorithmParameterSpec
* @see java.security.spec.DSAParameterSpec
* @see KeyPairGenerator
*
* @since 1.2
*/
public class AlgorithmParameters {
// The provider
private Provider provider;
// The provider implementation (delegate)
private AlgorithmParametersSpi paramSpi;
// The algorithm
private String algorithm;
// Has this object been initialized?
private boolean initialized = false;
/**
* Creates an AlgorithmParameters object.
*
* @param paramSpi the delegate
* @param provider the provider
* @param algorithm the algorithm
*/
protected AlgorithmParameters(AlgorithmParametersSpi paramSpi,
Provider provider, String algorithm)
{
this.paramSpi = paramSpi;
this.provider = provider;
this.algorithm = algorithm;
}
/**
* Returns the name of the algorithm associated with this parameter object.
*
* @return the algorithm name.
*/
public final String getAlgorithm() {
return this.algorithm;
}
/**
* 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 {@link Security#getProviders() Security.getProviders()} method.
*
*
The returned parameter object must be initialized via a call to
* {@code init}, using an appropriate parameter specification or
* parameter encoding.
*
* @implNote
* The JDK Reference Implementation additionally uses the
* {@code jdk.security.provider.preferred}
* {@link Security#getProperty(String) Security} property to determine
* the preferred provider order for the specified algorithm. This
* may be different than the order of providers returned by
* {@link Security#getProviders() Security.getProviders()}.
*
* @param 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.
*
* @return the new parameter object
*
* @throws NoSuchAlgorithmException if no {@code Provider} supports an
* {@code AlgorithmParametersSpi} implementation for the
* specified algorithm
*
* @throws NullPointerException if {@code algorithm} is {@code null}
*
* @see Provider
*/
public static AlgorithmParameters getInstance(String algorithm)
throws NoSuchAlgorithmException {
Objects.requireNonNull(algorithm, "null algorithm name");
try {
Object[] objs = Security.getImpl(algorithm, "AlgorithmParameters",
(String)null);
return new AlgorithmParameters((AlgorithmParametersSpi)objs[0],
(Provider)objs[1],
algorithm);
} catch(NoSuchProviderException e) {
throw new NoSuchAlgorithmException(algorithm + " not found");
}
}
/**
* 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 {@link Security#getProviders() Security.getProviders()} method.
*
*
The returned parameter object must be initialized via a call to
* {@code init}, using an appropriate parameter specification or
* parameter encoding.
*
* @param 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.
*
* @param provider the name of the provider.
*
* @return the new parameter object
*
* @throws IllegalArgumentException if the provider name is {@code null}
* or empty
*
* @throws NoSuchAlgorithmException if an {@code AlgorithmParametersSpi}
* implementation for the specified algorithm is not
* available from the specified provider
*
* @throws NoSuchProviderException if the specified provider is not
* registered in the security provider list
*
* @throws NullPointerException if {@code algorithm} is {@code null}
*
* @see Provider
*/
public static AlgorithmParameters getInstance(String algorithm,
String provider)
throws NoSuchAlgorithmException, NoSuchProviderException
{
Objects.requireNonNull(algorithm, "null algorithm name");
if (provider == null || provider.isEmpty())
throw new IllegalArgumentException("missing provider");
Object[] objs = Security.getImpl(algorithm, "AlgorithmParameters",
provider);
return new AlgorithmParameters((AlgorithmParametersSpi)objs[0],
(Provider)objs[1],
algorithm);
}
/**
* 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
* {@code init}, using an appropriate parameter specification or
* parameter encoding.
*
* @param 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.
*
* @param provider the name of the provider.
*
* @return the new parameter object
*
* @throws IllegalArgumentException if the provider is {@code null}
*
* @throws NoSuchAlgorithmException if an
* {@code AlgorithmParameterGeneratorSpi}
* implementation for the specified algorithm is not available
* from the specified {@code Provider} object
*
* @throws NullPointerException if {@code algorithm} is {@code null}
*
* @see Provider
*
* @since 1.4
*/
public static AlgorithmParameters getInstance(String algorithm,
Provider provider)
throws NoSuchAlgorithmException
{
Objects.requireNonNull(algorithm, "null algorithm name");
if (provider == null)
throw new IllegalArgumentException("missing provider");
Object[] objs = Security.getImpl(algorithm, "AlgorithmParameters",
provider);
return new AlgorithmParameters((AlgorithmParametersSpi)objs[0],
(Provider)objs[1],
algorithm);
}
/**
* Returns the provider of this parameter object.
*
* @return the provider of this parameter object
*/
public final Provider getProvider() {
return this.provider;
}
/**
* Initializes this parameter object using the parameters
* specified in {@code paramSpec}.
*
* @param 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.
*/
public final void init(AlgorithmParameterSpec paramSpec)
throws InvalidParameterSpecException
{
if (this.initialized)
throw new InvalidParameterSpecException("already initialized");
paramSpi.engineInit(paramSpec);
this.initialized = true;
}
/**
* 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.
*
* @param params the encoded parameters.
*
* @throws IOException on decoding errors, or if this parameter object
* has already been initialized.
*/
public final void init(byte[] params) throws IOException {
if (this.initialized)
throw new IOException("already initialized");
paramSpi.engineInit(params);
this.initialized = true;
}
/**
* Imports the parameters from {@code params} and decodes them
* according to the specified decoding scheme.
* If {@code 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.
*
* @param params the encoded parameters.
*
* @param format the name of the decoding scheme.
*
* @throws IOException on decoding errors, or if this parameter object
* has already been initialized.
*/
public final void init(byte[] params, String format) throws IOException {
if (this.initialized)
throw new IOException("already initialized");
paramSpi.engineInit(params, format);
this.initialized = true;
}
/**
* Returns a (transparent) specification of this parameter object.
* {@code paramSpec} identifies the specification class in which
* the parameters should be returned. It could, for example, be
* {@code DSAParameterSpec.class}, to indicate that the
* parameters should be returned in an instance of the
* {@code DSAParameterSpec} class.
*
* @param the type of the parameter specification to be returrned
* @param paramSpec the specification class in which
* the parameters should be returned.
*
* @return 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.
*/
public final
T getParameterSpec(Class paramSpec)
throws InvalidParameterSpecException
{
if (this.initialized == false) {
throw new InvalidParameterSpecException("not initialized");
}
return paramSpi.engineGetParameterSpec(paramSpec);
}
/**
* 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.
*
* @return the parameters encoded using their primary encoding format.
*
* @throws IOException on encoding errors, or if this parameter object
* has not been initialized.
*/
public final byte[] getEncoded() throws IOException
{
if (this.initialized == false) {
throw new IOException("not initialized");
}
return paramSpi.engineGetEncoded();
}
/**
* Returns the parameters encoded in the specified scheme.
* If {@code 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.
*
* @param format the name of the encoding format.
*
* @return the parameters encoded using the specified encoding scheme.
*
* @throws IOException on encoding errors, or if this parameter object
* has not been initialized.
*/
public final byte[] getEncoded(String format) throws IOException
{
if (this.initialized == false) {
throw new IOException("not initialized");
}
return paramSpi.engineGetEncoded(format);
}
/**
* Returns a formatted string describing the parameters.
*
* @return a formatted string describing the parameters, or null if this
* parameter object has not been initialized.
*/
public final String toString() {
if (this.initialized == false) {
return null;
}
return paramSpi.engineToString();
}
}