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 package org.bouncycastle.crypto.ec;
 
 
this does your basic Elgamal encryption algorithm using EC
    implements ECPairTransform
    private ECPublicKeyParameters key;
    private SecureRandom          random;

    
initialise the EC Elgamal engine.

Parameters:
param the necessary EC key parameters.
    public void init(
        CipherParameters    param)
    {
        if (param instanceof ParametersWithRandom)
        {
            ParametersWithRandom    p = (ParametersWithRandom)param;
            if (!(p.getParameters() instanceof ECPublicKeyParameters))
            {
                throw new IllegalArgumentException("ECPublicKeyParameters are required for new public key transform.");
            }
            this. = (ECPublicKeyParameters)p.getParameters();
            this. = p.getRandom();
        }
        else
        {
            if (!(param instanceof ECPublicKeyParameters))
            {
                throw new IllegalArgumentException("ECPublicKeyParameters are required for new public key transform.");
            }
            this. = (ECPublicKeyParameters)param;
            this. = new SecureRandom();
        }
    }

    
Transform an existing cipher text pair using the ElGamal algorithm. Note: the input cipherText will need to be preserved in order to complete the transformation to the new public key.

Parameters:
cipherText the EC point to process.
Returns:
returns a new ECPair representing the result of the process.
    public ECPair transform(ECPair cipherText)
    {
        if ( == null)
        {
            throw new IllegalStateException("ECNewPublicKeyTransform not initialised");
        }
        ECDomainParameters ec = .getParameters();
        BigInteger n = ec.getN();
        ECMultiplier basePointMultiplier = createBasePointMultiplier();
        BigInteger k = ECUtil.generateK(n);
        ECPoint[] gamma_phi = new ECPoint[]{
            basePointMultiplier.multiply(ec.getG(), k),
            .getQ().multiply(k).add(cipherText.getY())
        };
        ec.getCurve().normalizeAll(gamma_phi);
        return new ECPair(gamma_phi[0], gamma_phi[1]);
    }
    {
        return new FixedPointCombMultiplier();
    }
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