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javax.crypto
Class ExemptionMechanism
java.lang.Object
javax.crypto.ExemptionMechanism
-
public class ExemptionMechanism
- extends 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.
-
Since:
-
1.4
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
Returns an
Generates a
ExemptionMechanism object that implements the specified exemption mechanism algorithm. |
static
ExemptionMechanism
|
getInstance
(
String
algorithm,
Provider
Returns an
Generates a
ExemptionMechanism object
that implements
for
the specified exemption mechanism
algorithm.
algorithm from the specified provider.
|
static
ExemptionMechanism
|
getInstance
(
String
algorithm,
String
Returns an
Generates a
ExemptionMechanism object
that implements
for
the specified exemption mechanism
algorithm.
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. |
ExemptionMechanism
protected ExemptionMechanism(ExemptionMechanismSpi exmechSpi,
Provider provider,
String mechanism)
-
Creates a ExemptionMechanism object.
-
Parameters:
-
exmechSpi - the delegate
-
provider - the provider
-
mechanism - the exemption mechanism
getName
public final 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.
getInstance
public static final ExemptionMechanism getInstance(String algorithm)
throws NoSuchAlgorithmException
-
Returns an ExemptionMechanism object that implements the specified exemption mechanism algorithm.
Generates a 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.
This method traverses the list of registered security Providers, starting with the most preferred Provider. A new ExemptionMechanism object encapsulating the ExemptionMechanismSpi implementation from the first Provider that supports the specified algorithm is returned.
Note that the list of registered providers may be retrieved via the
Security.getProviders()
method.
-
-
Parameters:
-
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.
-
Returns:
-
the new ExemptionMechanism
object.
object
-
Throws:
-
NullPointerException
- if algorithm is null.
-
NoSuchAlgorithmException
- if no Provider supports an ExemptionMechanismSpi implementation for the specified algorithm.
-
See Also:
-
Provider
- if the specified algorithm is not available in the default provider package or any of the other provider packages that were searched.
getInstance
public static final ExemptionMechanism getInstance(String algorithm,
String provider)
throws NoSuchAlgorithmException,
NoSuchProviderException
-
Returns an
Generates a
ExemptionMechanism object
that implements
for
the specified exemption mechanism
algorithm.
from the specified provider.
A new ExemptionMechanism object encapsulating the ExemptionMechanismSpi 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
Security.getProviders()
method.
-
-
Parameters:
-
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.
provider
-
Returns:
-
the new ExemptionMechanism
object.
object
-
Throws:
-
NullPointerException
- if algorithm is null.
-
NoSuchAlgorithmException
- if
an ExemptionMechanismSpi implementation for
the specified algorithm is not available from the specified provider. -
NoSuchProviderException
- if the specified provider
is
has
not
registered in the security provider list.
been configured.
-
IllegalArgumentException
- if the provider is null or empty.
-
See Also:
-
Provider
- if the provider is null.
getInstance
public static final ExemptionMechanism getInstance(String algorithm,
Provider provider)
throws NoSuchAlgorithmException
-
Returns an ExemptionMechanism object that implements the specified exemption mechanism algorithm.
Generates a ExemptionMechanism object for the specified exemption mechanism algorithm from the specified provider. Note: the provider doesn't have to be registered.
A new ExemptionMechanism object encapsulating the ExemptionMechanismSpi implementation from the specified Provider object is returned. Note that the specified Provider object does not have to be registered in the provider list.
-
-
Parameters:
-
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.
provider
-
Returns:
-
the new ExemptionMechanism
object.
object
-
Throws:
-
NullPointerException
- if algorithm is null.
-
NoSuchAlgorithmException
- if
an ExemptionMechanismSpi implementation for
the specified algorithm is not available from the specified
Provider object.
provider.
-
IllegalArgumentException
- if the provider is null.
-
See Also:
-
Provider
getProvider
public final Provider getProvider()
-
Returns the provider of this ExemptionMechanism object.
-
-
Returns:
-
the provider of this ExemptionMechanism object.
isCryptoAllowed
public final boolean isCryptoAllowed(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.
-
-
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; false if key is null.
-
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 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.
-
-
Parameters:
-
inputLen - the input length (in bytes)
-
Returns:
-
the required output buffer size (in bytes)
-
Throws:
-
IllegalStateException
- if this exemption mechanism is in a wrong state (e.g., has not yet been initialized)
init
public final void init(Key key)
throws 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.
-
-
Parameters:
-
key - the key for this exemption mechanism
-
Throws:
-
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(Key key,
AlgorithmParameterSpec params)
throws InvalidKeyException,
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.
-
-
Parameters:
-
key - the key for this exemption mechanism
-
params - the algorithm parameters
-
Throws:
-
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.
init
public final void init(Key key,
AlgorithmParameters params)
throws InvalidKeyException,
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.
-
-
Parameters:
-
key - the key for this exemption mechanism
-
params - the algorithm parameters
-
Throws:
-
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.
genExemptionBlob
public final byte[] genExemptionBlob()
throws IllegalStateException,
ExemptionMechanismException
-
Generates the exemption mechanism key blob.
-
-
Returns:
-
the new buffer with the result key blob.
-
Throws:
-
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 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.
-
-
Parameters:
-
output - the buffer for the result
-
Returns:
-
the number of bytes stored in output
-
Throws:
-
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 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.
-
-
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:
-
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
Object
-