javax.crypto
Class ExemptionMechanism

java.lang.Object
  |
  +--javax.crypto.ExemptionMechanism

public class ExemptionMechanism

extends java.lang.Object

This class provides the functionality of an exemption mechanism, examples of which are key recovery, key weakening, and key escrow.

Applications or applets that use an exemption mechanism may be granted stronger encryption capabilities than those which don't.

IMPLEMENTATION NOTE: This implementation does not support exemption mechanisms. As a result, all invocations to the declared methods throw one of exceptions declared in their signature.

Since:

1.4

Constructor Summary

protected

ExemptionMechanism(ExemptionMechanismSpi exmechSpi, java.security.Provider provider, java.lang.String mechanism) Creates a ExemptionMechanism object.

Method Summary

protected void	finalize() Ensures that the key stored away by this ExemptionMechanism object will be wiped out when there are no more references to it.
byte[]	genExemptionBlob() Generates the exemption mechanism key blob.
int	genExemptionBlob(byte[] output) Generates the exemption mechanism key blob, and stores the result in the output buffer.
int	genExemptionBlob(byte[] output, int outputOffset) Generates the exemption mechanism key blob, and stores the result in the output buffer, starting at outputOffset inclusive.
static ExemptionMechanism	getInstance(java.lang.String mechanism) Generates a ExemptionMechanism object that implements the specified exemption mechanism.
static ExemptionMechanism	getInstance(java.lang.String mechanism, java.security.Provider provider) Generates a ExemptionMechanism object for the specified exemption mechanism from the specified provider.
static ExemptionMechanism	getInstance(java.lang.String mechanism, java.lang.String provider) Generates a ExemptionMechanism object for the specified exemption mechanism from the specified provider.
java.lang.String	getName() Returns the exemption mechanism name of this ExemptionMechanism object.
int	getOutputSize(int inputLen) Returns the length in bytes that an output buffer would need to be in order to hold the result of the next genExemptionBlob operation, given the input length inputLen (in bytes).
java.security.Provider	getProvider() Returns the provider of this ExemptionMechanism object.
void	init(java.security.Key key) Initializes this exemption mechanism with a key.
void	init(java.security.Key key, java.security.AlgorithmParameters params) Initializes this exemption mechanism with a key and a set of algorithm parameters.
void	init(java.security.Key key, java.security.spec.AlgorithmParameterSpec params) Initializes this exemption mechanism with a key and a set of algorithm parameters.
boolean	isCryptoAllowed(java.security.Key key) Returns whether the result blob has been generated successfully by this exemption mechanism.

Methods inherited from class java.lang.Object

clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ExemptionMechanism

protected ExemptionMechanism(ExemptionMechanismSpi exmechSpi,
                             java.security.Provider provider,
                             java.lang.String mechanism)

Creates a ExemptionMechanism object.

Parameters:

exmechSpi - the delegate.

provider - the provider.

mechanism - the exemption mechanism.

Method Detail

getInstance

public static final ExemptionMechanism getInstance(java.lang.String mechanism)
                                            throws java.security.NoSuchAlgorithmException

Generates a ExemptionMechanism object that implements the specified exemption mechanism. If the default provider package provides an implementation of the requested exemption mechanism, an instance of ExemptionMechanism containing that implementation is returned. If the exemption mechanism is not available in the default provider package, other provider packages are searched.

IMPLEMENTATION NOTE: This implementation always throws a NoSuchAlgorithmException.

Parameters:

mechanism - the standard name of the requested exemption mechanism. See Appendix A in the Java Cryptography Extension Reference Guide for information about standard exemption mechanism names.

Returns:

the new ExemptionMechanism object

Throws:

java.security.NoSuchAlgorithmException - if the specified exemption mechanism is not available in the default provider package or any of the other provider packages that were searched.

getInstance

public static final ExemptionMechanism getInstance(java.lang.String mechanism,
                                                   java.lang.String provider)
                                            throws java.security.NoSuchAlgorithmException,
                                                   java.security.NoSuchProviderException

Generates a ExemptionMechanism object for the specified exemption mechanism from the specified provider.

IMPLEMENTATION NOTE: This implementation always throws a NoSuchAlgorithmException, except when the designated provider is null, in which case it throws an IllegalArgumentException .

Parameters:

mechanism - the standard name of the requested exemption mechanism. See Appendix A in the Java Cryptography Extension Reference Guide for information about standard exemption mechanism names.

provider - the name of the provider.

Returns:

the new ExemptionMechanism object.

Throws:

java.security.NoSuchAlgorithmException - if the specified exemption mechanism is not available from the specified provider.

java.security.NoSuchProviderException - if the specified provider has not been configured.

java.lang.IllegalArgumentException - if the provider is null.

getInstance

public static final ExemptionMechanism getInstance(java.lang.String mechanism,
                                                   java.security.Provider provider)
                                            throws java.security.NoSuchAlgorithmException

Generates a ExemptionMechanism object for the specified exemption mechanism from the specified provider. Note: the provider doesn't have to be registered.

IMPLEMENTATION NOTE: This implementation always throws a NoSuchAlgorithmException, except when the designated provider is null, in which case it throws an IllegalArgumentException .

Parameters:

mechanism - the standard name of the requested exemption mechanism. See Appendix A in the Java Cryptography Extension Reference Guide for information about standard exemption mechanism names.

provider - the provider.

Returns:

the new ExemptionMechanism object.

Throws:

java.security.NoSuchAlgorithmException - if the specified exemption mechanism is not available from the specified provider.

java.lang.IllegalArgumentException - if the provider is null.

getName

public final java.lang.String getName()

Returns the exemption mechanism name of this ExemptionMechanism object.

This is the same name that was specified in one of the getInstance() calls that created this ExemptionMechanism object.

Returns:

the exemption mechanism name of this ExemptionMechanism object.

getProvider

public final java.security.Provider getProvider()

Returns the provider of this ExemptionMechanism object.

Returns:

the provider of this ExemptionMechanism object.

isCryptoAllowed

public final boolean isCryptoAllowed(java.security.Key key)
                              throws ExemptionMechanismException

Returns whether the result blob has been generated successfully by this exemption mechanism.

The method also makes sure that the key passed in is the same as the one this exemption mechanism used in initializing and generating phases.

IMPLEMENTATION NOTE: This implementation always throws a ExemptionMechanismException

Parameters:

key - the key the crypto is going to use.

Returns:

whether the result blob of the same key has been generated successfully by this exemption mechanism.

Throws:

ExemptionMechanismException - if problem(s) encountered while determining whether the result blob has been generated successfully by this exemption mechanism object.

getOutputSize

public final int getOutputSize(int inputLen)
                        throws java.lang.IllegalStateException

Returns the length in bytes that an output buffer would need to be in order to hold the result of the next genExemptionBlob operation, given the input length inputLen (in bytes).

The actual output length of the next genExemptionBlob() call may be smaller than the length returned by this method.

IMPLEMENTATION NOTE: This implementation always throws an IllegalStateException

Parameters:

inputLen - the input length (in bytes).

Returns:

the required output buffer size (in bytes).

Throws:

java.lang.IllegalStateException - if this exemption mechanism is in a wrong state (e.g., has not yet been initialized).

init

public final void init(java.security.Key key)
                throws java.security.InvalidKeyException,
                       ExemptionMechanismException

Initializes this exemption mechanism with a key.

If this exemption mechanism requires any algorithm parameters that cannot be derived from the given key, the underlying exemption mechanism implementation is supposed to generate the required parameters itself (using provider-specific default values); in the case that algorithm parameters must be specified by the caller, an InvalidKeyException is raised.

IMPLEMENTATION NOTE: This implementation always throws an ExemptionMechanismException

Parameters:

key - the key for this exemption mechanism.

Throws:

java.security.InvalidKeyException - if the given key is inappropriate for this exemption mechanism.

ExemptionMechanismException - if problem(s) encountered in the process of initializing.

init

public final void init(java.security.Key key,
                       java.security.spec.AlgorithmParameterSpec params)
                throws java.security.InvalidKeyException,
                       java.security.InvalidAlgorithmParameterException,
                       ExemptionMechanismException

Initializes this exemption mechanism with a key and a set of algorithm parameters.

If this exemption mechanism requires any algorithm parameters and params is null, the underlying exemption mechanism implementation is supposed to generate the required parameters itself (using provider- specific default values); in the case that algorithm parameters must be specified by the caller, an InvalidAlgorithmParameterException is raised.

IMPLEMENTATION NOTE: This implementation always throws an ExemptionMechanismException

Parameters:

key - the key for this exemption mechanism.

params - the algorithm parameters.

Throws:

java.security.InvalidKeyException - if the given key is inappropriate for this exemption mechanism.

java.security.InvalidAlgorithmParameterException - if the given algorithm parameters are inappropriate for this exemption mechanism.

ExemptionMechanismException - if problem(s) encountered in the process of initializing.

init

public final void init(java.security.Key key,
                       java.security.AlgorithmParameters params)
                throws java.security.InvalidKeyException,
                       java.security.InvalidAlgorithmParameterException,
                       ExemptionMechanismException

Initializes this exemption mechanism with a key and a set of algorithm parameters.

If this exemption mechanism requires any algorithm parameters and params is null, the underlying exemption mechanism implementation is supposed to generate the required parameters itself (using provider- specific default values); in the case that algorithm parameters must be specified by the caller, an InvalidAlgorithmParameterException is raised.

IMPLEMENTATION NOTE: This implementation always throws an ExemptionMechanismException

Parameters:

key - the key for this exemption mechanism.

params - the algorithm parameters.

Throws:

java.security.InvalidKeyException - if the given key is inappropriate for this exemption mechanism.

java.security.InvalidAlgorithmParameterException - if the given algorithm parameters are inappropriate for this exemption mechanism.

ExemptionMechanismException - if problem(s) encountered in the process of initializing.

genExemptionBlob

public final byte[] genExemptionBlob()
                              throws java.lang.IllegalStateException,
                                     ExemptionMechanismException

Generates the exemption mechanism key blob.

IMPLEMENTATION NOTE: This implementation always throws an ExemptionMechanismException

Returns:

the new buffer with the result key blob.

Throws:

java.lang.IllegalStateException - if this exemption mechanism is in a wrong state (e.g., has not been initialized).

ExemptionMechanismException - if problem(s) encountered in the process of generating.

genExemptionBlob

public final int genExemptionBlob(byte[] output)
                           throws java.lang.IllegalStateException,
                                  ShortBufferException,
                                  ExemptionMechanismException

Generates the exemption mechanism key blob, and stores the result in the output buffer.

If the output buffer is too small to hold the result, a ShortBufferException is thrown. In this case, repeat this call with a larger output buffer. Use getOutputSize() to determine how big the output buffer should be.

IMPLEMENTATION NOTE: This implementation always throws an ExemptionMechanismException

Parameters:

output - the buffer for the result.

Returns:

the number of bytes stored in output.

Throws:

java.lang.IllegalStateException - if this exemption mechanism is in a wrong state (e.g., has not been initialized).

ShortBufferException - if the given output buffer is too small to hold the result.

ExemptionMechanismException - if problem(s) encountered in the process of generating.

genExemptionBlob

public final int genExemptionBlob(byte[] output,
                                  int outputOffset)
                           throws java.lang.IllegalStateException,
                                  ShortBufferException,
                                  ExemptionMechanismException

Generates the exemption mechanism key blob, and stores the result in the output buffer, starting at outputOffset inclusive.

If the output buffer is too small to hold the result, a ShortBufferException is thrown. In this case, repeat this call with a larger output buffer. Use getOutputSize() to determine how big the output buffer should be.

IMPLEMENTATION NOTE: This implementation always throws an ExemptionMechanismException

Parameters:

output - the buffer for the result.

outputOffset - the offset in output where the result is stored.

Returns:

the number of bytes stored in output

Throws:

java.lang.IllegalStateException - if this exemption mechanism is in a wrong state (e.g., has not been initialized).

ShortBufferException - if the given output buffer is too small to hold the result.

ExemptionMechanismException - if problem(s) encountered in the process of generating.

finalize

protected void finalize()

Ensures that the key stored away by this ExemptionMechanism object will be wiped out when there are no more references to it.

Overrides:

finalize in class java.lang.Object