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java.lang.Objectjavax.crypto.ExemptionMechanism
public class ExemptionMechanism
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.
Constructor Summary | |
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protected |
ExemptionMechanism(ExemptionMechanismSpi exmechSpi,
Provider provider,
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(String algorithm)
Generates a ExemptionMechanism object that implements
the specified exemption mechanism algorithm. |
static ExemptionMechanism |
getInstance(String algorithm,
Provider provider)
Generates a ExemptionMechanism object for the specified
exemption mechanism algorithm from the specified provider. |
static ExemptionMechanism |
getInstance(String algorithm,
String provider)
Generates a ExemptionMechanism object for the specified
exemption mechanism from the specified provider. |
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). |
Provider |
getProvider()
Returns the provider of this ExemptionMechanism
object. |
void |
init(Key key)
Initializes this exemption mechanism with a key. |
void |
init(Key key,
AlgorithmParameters params)
Initializes this exemption mechanism with a key and a set of algorithm parameters. |
void |
init(Key key,
AlgorithmParameterSpec params)
Initializes this exemption mechanism with a key and a set of algorithm parameters. |
boolean |
isCryptoAllowed(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 |
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protected ExemptionMechanism(ExemptionMechanismSpi exmechSpi,
Provider provider,
String mechanism)
exmechSpi
- the delegateprovider
- the providermechanism
- the exemption
mechanismMethod Detail |
---|
public final String getName()
ExemptionMechanism
object.
This is the same name that was specified in one of the getInstance
calls that created this ExemptionMechanism
object.
ExemptionMechanism
object.public static final ExemptionMechanism getInstance(String algorithm)
throws NoSuchAlgorithmException
ExemptionMechanism
object that implements the specified exemption mechanism algorithm. If
the default provider package provides an implementation of the
requested exemption mechanism algorithm, 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.
algorithm
- 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.
ExemptionMechanism
object
NullPointerException
- if algorithm
is null.
NoSuchAlgorithmException
- if the specified algorithm is not available in the default provider
package or any of the other provider packages that were searched.public static final ExemptionMechanism getInstance(String algorithm,
String provider)
throws NoSuchAlgorithmException,
NoSuchProviderException
ExemptionMechanism
object for the specified exemption mechanism from the specified
provider.
algorithm
- 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
ExemptionMechanism
object
NullPointerException
- if algorithm
is null.
NoSuchAlgorithmException
- if the specified algorithm is not available from the specified
provider.
NoSuchProviderException
- if the specified provider has not been configured.
IllegalArgumentException
- if the provider
is null.public static final ExemptionMechanism getInstance(String algorithm,
Provider provider)
throws NoSuchAlgorithmException
ExemptionMechanism
object for the specified exemption mechanism algorithm from the
specified provider. Note: the provider
doesn't have to be registered.
algorithm
- 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
ExemptionMechanism
object
NullPointerException
- if algorithm
is null.
NoSuchAlgorithmException
- if the specified algorithm is not available from the specified
provider.
IllegalArgumentException
- if the provider
is null.public final Provider getProvider()
ExemptionMechanism
object.
ExemptionMechanism
object.public final boolean isCryptoAllowed(Key key)
throws ExemptionMechanismException
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.
key
- the key the crypto is
going to use.
key
is null.
ExemptionMechanismException
- if problem(s) encountered while determining whether the result blob
has been generated successfully by this exemption mechanism object.public final int getOutputSize(int inputLen)
throws IllegalStateException
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.
inputLen
- the input length
(in bytes)
IllegalStateException
- if this exemption mechanism is in a wrong state (e.g., has not yet
been initialized)public final void init(Key key)
throws InvalidKeyException,
ExemptionMechanismException
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.
key
- the key for this
exemption mechanism
InvalidKeyException
- if the given key is inappropriate for this exemption mechanism.
ExemptionMechanismException
- if problem(s) encountered in the process of initializing.public final void init(Key key,
AlgorithmParameterSpec params)
throws InvalidKeyException,
InvalidAlgorithmParameterException,
ExemptionMechanismException
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.
key
- the key for this
exemption mechanismparams
- the algorithm
parameters
InvalidKeyException
- if the given key is inappropriate for this exemption mechanism.
InvalidAlgorithmParameterException
- if the given algorithm parameters are inappropriate for this
exemption mechanism.
ExemptionMechanismException
- if problem(s) encountered in the process of initializing.public final void init(Key key,
AlgorithmParameters params)
throws InvalidKeyException,
InvalidAlgorithmParameterException,
ExemptionMechanismException
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.
key
- the key for this
exemption mechanismparams
- the algorithm
parameters
InvalidKeyException
- if the given key is inappropriate for this exemption mechanism.
InvalidAlgorithmParameterException
- if the given algorithm parameters are inappropriate for this
exemption mechanism.
ExemptionMechanismException
- if problem(s) encountered in the process of initializing.public final byte[] genExemptionBlob()
throws IllegalStateException,
ExemptionMechanismException
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.public final int genExemptionBlob(byte[] output)
throws IllegalStateException,
ShortBufferException,
ExemptionMechanismException
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.
output
- the buffer for the
result
output
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.public final int genExemptionBlob(byte[] output,
int outputOffset)
throws IllegalStateException,
ShortBufferException,
ExemptionMechanismException
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.
output
- the buffer for the
resultoutputOffset
- the offset in output
where the result is stored
output
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.protected void finalize()
finalize
in class Object
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