org.spongycastle.crypto.engines

Class ElGamalEngine

java.lang.Object

org.spongycastle.crypto.engines.ElGamalEngine

All Implemented Interfaces:

AsymmetricBlockCipher

public class ElGamalEngine
extends java.lang.Object
implements AsymmetricBlockCipher

this does your basic ElGamal algorithm.

Constructor Summary

Constructors

Constructor and Description
ElGamalEngine()

Method Summary

Modifier and Type	Method and Description
int	getInputBlockSize() Return the maximum size for an input block to this engine.
int	getOutputBlockSize() Return the maximum size for an output block to this engine.
void	init(boolean forEncryption, CipherParameters param) initialise the ElGamal engine.
byte[]	processBlock(byte[] in, int inOff, int inLen) Process a single block using the basic ElGamal algorithm.

Methods inherited from class java.lang.Object

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

Constructor Detail

ElGamalEngine

public ElGamalEngine()

Method Detail

init

public void init(boolean forEncryption,
                 CipherParameters param)

initialise the ElGamal engine.

Specified by:

init in interface AsymmetricBlockCipher

Parameters:

forEncryption - true if we are encrypting, false otherwise.

param - the necessary ElGamal key parameters.

getInputBlockSize

public int getInputBlockSize()

Return the maximum size for an input block to this engine. For ElGamal this is always one byte less than the size of P on encryption, and twice the length as the size of P on decryption.

Specified by:

getInputBlockSize in interface AsymmetricBlockCipher

Returns:

maximum size for an input block.

getOutputBlockSize

public int getOutputBlockSize()

Return the maximum size for an output block to this engine. For ElGamal this is always one byte less than the size of P on decryption, and twice the length as the size of P on encryption.

Specified by:

getOutputBlockSize in interface AsymmetricBlockCipher

Returns:

maximum size for an output block.

processBlock

public byte[] processBlock(byte[] in,
                           int inOff,
                           int inLen)

Process a single block using the basic ElGamal algorithm.

Specified by:

processBlock in interface AsymmetricBlockCipher

Parameters:

in - the input array.

inOff - the offset into the input buffer where the data starts.

inLen - the length of the data to be processed.

Returns:

the result of the ElGamal process.

Throws:

DataLengthException - the input block is too large.