javax.crypto
Class ExemptionMechanism

java.lang.Object
  extended by javax.crypto.ExemptionMechanism

public class ExemptionMechanism
extends Object

An exemption mechanism, which will conditionally allow cryptography where it is not normally allowed, implements things such as key recovery, key weakening, or key escrow.

Implementation note: this class is present for API-compatibility only; it is not actually used anywhere in this library and this library does not, in general, support crypto weakening.

Since:
1.4

Constructor Summary
protected ExemptionMechanism(ExemptionMechanismSpi emSpi, Provider provider, String mechanism)
           
 
Method Summary
protected  void finalize()
          Called on an object by the Virtual Machine at most once, at some point after the Object is determined unreachable but before it is destroyed.
 byte[] genExemptionBlob()
           
 int genExemptionBlob(byte[] output)
           
 int genExemptionBlob(byte[] output, int outputOffset)
           
static ExemptionMechanism getInstance(String mechanism)
          Create an instance of ExemptionMechanism for a designated mechanism from the first Security Provider offering it.
static ExemptionMechanism getInstance(String mechanism, Provider provider)
          Create an instance of ExemptionMechanism for a designated mechanism from a designated provider.
static ExemptionMechanism getInstance(String mechanism, String provider)
          Create an instance of ExemptionMechanism for a designated mechanism from a named provider.
 String getName()
           
 int getOutputSize(int inputLength)
           
 Provider getProvider()
           
 void init(Key key)
           
 void init(Key key, AlgorithmParameters params)
           
 void init(Key key, AlgorithmParameterSpec params)
           
 boolean isCryptoAllowed(Key key)
           
 
Methods inherited from class java.lang.Object
clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

ExemptionMechanism

protected ExemptionMechanism(ExemptionMechanismSpi emSpi,
                             Provider provider,
                             String mechanism)
Method Detail

getInstance

public static final ExemptionMechanism getInstance(String mechanism)
                                            throws NoSuchAlgorithmException
Create an instance of ExemptionMechanism for a designated mechanism from the first Security Provider offering it.

Parameters:
mechanism - the name of the exemption mechanism to create.
Returns:
a newly created instance of ExemptionMechanism.
Throws:
IllegalArgumentException - if the provider is null.
NoSuchAlgorithmException - if no such exemption mechanism is available from any known Security Provider.
IllegalArgumentException - if mechanism is null or is an empty string.

getInstance

public static final ExemptionMechanism getInstance(String mechanism,
                                                   String provider)
                                            throws NoSuchAlgorithmException,
                                                   NoSuchProviderException
Create an instance of ExemptionMechanism for a designated mechanism from a named provider.

Parameters:
mechanism - the name of the exemption mechanism to create.
provider - the security provider to provide the exemption mechanism.
Returns:
a newly created instance of ExemptionMechanism.
Throws:
NoSuchAlgorithmException - if no such exemption mechanism is available from the named provider.
NoSuchProviderException - if no Security Provider with the designated name is known to the underlying JVM.
IllegalArgumentException - if either mechanism or provider is null, or if mechanism is an empty string.

getInstance

public static final ExemptionMechanism getInstance(String mechanism,
                                                   Provider provider)
                                            throws NoSuchAlgorithmException
Create an instance of ExemptionMechanism for a designated mechanism from a designated provider.

Parameters:
mechanism - the name of the exemption mechanism to create.
provider - the security provider to provide the exemption mechanism.
Returns:
a newly created instance of ExemptionMechanism.
Throws:
NoSuchAlgorithmException - if an exemption mechanism could not be created.
IllegalArgumentException - if either mechanism or provider is null, or if mechanism is an empty string.

genExemptionBlob

public final byte[] genExemptionBlob()
                              throws IllegalStateException,
                                     ExemptionMechanismException
Throws:
IllegalStateException
ExemptionMechanismException

genExemptionBlob

public final int genExemptionBlob(byte[] output)
                           throws IllegalStateException,
                                  ExemptionMechanismException,
                                  ShortBufferException
Throws:
IllegalStateException
ExemptionMechanismException
ShortBufferException

genExemptionBlob

public final int genExemptionBlob(byte[] output,
                                  int outputOffset)
                           throws IllegalStateException,
                                  ExemptionMechanismException,
                                  ShortBufferException
Throws:
IllegalStateException
ExemptionMechanismException
ShortBufferException

getName

public final String getName()

getOutputSize

public final int getOutputSize(int inputLength)
                        throws IllegalStateException
Throws:
IllegalStateException

getProvider

public final Provider getProvider()

init

public final void init(Key key)
                throws ExemptionMechanismException,
                       InvalidKeyException
Throws:
ExemptionMechanismException
InvalidKeyException

init

public final void init(Key key,
                       AlgorithmParameters params)
                throws ExemptionMechanismException,
                       InvalidAlgorithmParameterException,
                       InvalidKeyException
Throws:
ExemptionMechanismException
InvalidAlgorithmParameterException
InvalidKeyException

init

public final void init(Key key,
                       AlgorithmParameterSpec params)
                throws ExemptionMechanismException,
                       InvalidAlgorithmParameterException,
                       InvalidKeyException
Throws:
ExemptionMechanismException
InvalidAlgorithmParameterException
InvalidKeyException

isCryptoAllowed

public final boolean isCryptoAllowed(Key key)
                              throws ExemptionMechanismException
Throws:
ExemptionMechanismException

finalize

protected void finalize()
Description copied from class: Object
Called on an object by the Virtual Machine at most once, at some point after the Object is determined unreachable but before it is destroyed. You would think that this means it eventually is called on every Object, but this is not necessarily the case. If execution terminates abnormally, garbage collection does not always happen. Thus you cannot rely on this method to always work. For finer control over garbage collection, use references from the java.lang.ref package.

Virtual Machines are free to not call this method if they can determine that it does nothing important; for example, if your class extends Object and overrides finalize to do simply super.finalize().

finalize() will be called by a Thread that has no locks on any Objects, and may be called concurrently. There are no guarantees on the order in which multiple objects are finalized. This means that finalize() is usually unsuited for performing actions that must be thread-safe, and that your implementation must be use defensive programming if it is to always work.

If an Exception is thrown from finalize() during garbage collection, it will be patently ignored and the Object will still be destroyed.

It is allowed, although not typical, for user code to call finalize() directly. User invocation does not affect whether automatic invocation will occur. It is also permitted, although not recommended, for a finalize() method to "revive" an object by making it reachable from normal code again.

Unlike constructors, finalize() does not get called for an object's superclass unless the implementation specifically calls super.finalize().

The default implementation does nothing.

Overrides:
finalize in class Object
See Also:
System.gc(), System.runFinalizersOnExit(boolean), java.lang.ref