org.spongycastle.crypto.ec

Class ECFixedTransform

java.lang.Object

org.spongycastle.crypto.ec.ECFixedTransform

All Implemented Interfaces:

ECPairFactorTransform, ECPairTransform

public class ECFixedTransform
extends java.lang.Object
implements ECPairFactorTransform

this transforms the original randomness used for an ElGamal encryption by a fixed value.

Constructor Summary

Constructors

Constructor and Description
ECFixedTransform(java.math.BigInteger k)

Method Summary

Modifier and Type	Method and Description
protected ECMultiplier	createBasePointMultiplier()
java.math.BigInteger	getTransformValue() Return the last transform value used by the transform
void	init(CipherParameters param) initialise the underlying EC ElGamal engine.
ECPair	transform(ECPair cipherText) Transform an existing cipher text pair using the ElGamal algorithm.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ECFixedTransform

public ECFixedTransform(java.math.BigInteger k)

Method Detail

init

public void init(CipherParameters param)

initialise the underlying EC ElGamal engine.

Specified by:

init in interface ECPairTransform

Parameters:

param - the necessary EC key parameters.

transform

public ECPair transform(ECPair cipherText)

Transform an existing cipher text pair using the ElGamal algorithm. Note: it is assumed this transform has been initialised with the same public key that was used to create the original cipher text.

Specified by:

transform in interface ECPairTransform

Parameters:

cipherText - the EC point to process.

Returns:

returns a new ECPair representing the result of the process.

getTransformValue

public java.math.BigInteger getTransformValue()

Return the last transform value used by the transform

Specified by:

getTransformValue in interface ECPairFactorTransform

Returns:

a BigInteger representing k value.

createBasePointMultiplier

protected ECMultiplier createBasePointMultiplier()