ExemptionMechanismSpi

AI-generated Key Takeaways

• ExemptionMechanismSpi is a Service Provider Interface (SPI) for the ExemptionMechanism class, defining methods for cryptographic service providers to implement specific exemption mechanisms.

• It provides methods for generating and initializing exemption mechanism key blobs using keys and algorithm parameters.

• Implementations must provide the logic for generating key blobs, handling output buffers, and initializing the mechanism with appropriate keys and parameters.

• This class is abstract and requires cryptographic service providers to extend it and provide concrete implementations for the defined methods.

public abstract class ExemptionMechanismSpi extends Object

This class defines the Service Provider Interface (SPI) for the ExemptionMechanism class. All the abstract methods in this class must be implemented by each cryptographic service provider who wishes to supply the implementation of a particular exemption mechanism.

Public Constructor Summary

ExemptionMechanismSpi()

Protected Method Summary

abstract byte[]	engineGenExemptionBlob() Generates the exemption mechanism key blob.
abstract int	engineGenExemptionBlob(byte[] output, int outputOffset) Generates the exemption mechanism key blob, and stores the result in the output buffer, starting at outputOffset inclusive.
abstract int	engineGetOutputSize(int inputLen) Returns the length in bytes that an output buffer would need to be in order to hold the result of the next engineGenExemptionBlob operation, given the input length inputLen (in bytes).
abstract void	engineInit(Key key) Initializes this exemption mechanism with a key.
abstract void	engineInit(Key key, AlgorithmParameterSpec params) Initializes this exemption mechanism with a key and a set of algorithm parameters.
abstract void	engineInit(Key key, AlgorithmParameters params) Initializes this exemption mechanism with a key and a set of algorithm parameters.

Inherited Method Summary

From class java.lang.Object

Object	clone() Creates and returns a copy of this Object.
boolean	equals(Object obj) Compares this instance with the specified object and indicates if they are equal.
void	finalize() Invoked when the garbage collector has detected that this instance is no longer reachable.
final Class<?>	getClass() Returns the unique instance of Class that represents this object's class.
int	hashCode() Returns an integer hash code for this object.
final void	notify() Causes a thread which is waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
final void	notifyAll() Causes all threads which are waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
String	toString() Returns a string containing a concise, human-readable description of this object.
final void	wait(long timeout, int nanos) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait(long timeout) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait() Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object.

Public Constructors

public ExemptionMechanismSpi ()

Protected Methods

protected abstract byte[] engineGenExemptionBlob ()

Generates the exemption mechanism key blob.

Returns

• the new buffer with the result key blob.

Throws

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

protected abstract int engineGenExemptionBlob (byte[] output, int outputOffset)

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 engineGetOutputSize 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

ShortBufferException	if the given output buffer is too small to hold the result.
ExemptionMechanismException	if problem(s) encountered in the process of generating.

protected abstract int engineGetOutputSize (int inputLen)

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

The actual output length of the next engineGenExemptionBlob 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)

protected abstract void engineInit (Key key)

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.

protected abstract void engineInit (Key key, AlgorithmParameterSpec params)

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.

protected abstract void engineInit (Key key, AlgorithmParameters params)

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.