javax.crypto

Class 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

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, String provider)
Create an instance of ExemptionMechanism for a designated mechanism from a named provider.
static ExemptionMechanism
getInstance(String mechanism, Provider provider)
Create an instance of ExemptionMechanism for a designated mechanism from a designated 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, extends Object> getClass, finalize, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

ExemptionMechanism

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

Method Details

finalize

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. 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 interface Object

genExemptionBlob

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

genExemptionBlob

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

genExemptionBlob

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

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.

getName

public final String getName()

getOutputSize

public final int getOutputSize(int inputLength)
            throws IllegalStateException

getProvider

public final Provider getProvider()

init

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

init

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

init

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

isCryptoAllowed

public final boolean isCryptoAllowed(Key key)
            throws ExemptionMechanismException

ExemptionMechanism.java -- Generic crypto-weakening mechanism. Copyright (C) 2004 Free Software Foundation, Inc. This file is part of GNU Classpath. GNU Classpath is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. GNU Classpath is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GNU Classpath; see the file COPYING. If not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. Linking this library statically or dynamically with other modules is making a combined work based on this library. Thus, the terms and conditions of the GNU General Public License cover the whole combination. As a special exception, the copyright holders of this library give you permission to link this library with independent modules to produce an executable, regardless of the license terms of these independent modules, and to copy and distribute the resulting executable under terms of your choice, provided that you also meet, for each linked independent module, the terms and conditions of the license of that module. An independent module is a module which is not derived from or based on this library. If you modify this library, you may extend this exception to your version of the library, but you are not obligated to do so. If you do not wish to do so, delete this exception statement from your version.