1.4 fixes.

3 files changed, 578 insertions, 495 deletions

diff --git a/core/src/main/java/org/bouncycastle/crypto/engines/CramerShoupCiphertext.java b/core/src/main/java/org/bouncycastle/crypto/engines/CramerShoupCiphertext.java
index 1e43eb2a..0d8ba19d 100644
--- a/core/src/main/java/org/bouncycastle/crypto/engines/CramerShoupCiphertext.java
+++ b/core/src/main/java/org/bouncycastle/crypto/engines/CramerShoupCiphertext.java
@@ -3,160 +3,177 @@ package org.bouncycastle.crypto.engines;
 import java.math.BigInteger;
 
 /**
- * 
  * Class, holding Cramer Shoup ciphertexts (u1, u2, e, v)
- *
  */
-public class CramerShoupCiphertext {
-	
-	BigInteger u1, u2, e, v;
-	
-	public CramerShoupCiphertext() {
-		
-	}
-	
-	public CramerShoupCiphertext(BigInteger u1, BigInteger u2, BigInteger e, BigInteger v){
-		this.u1 = u1;
-		this.u2 = u2;
-		this.e = e;
-		this.v = v;
-	}
-	
-	public CramerShoupCiphertext(byte[] c){
-		int off = 0, s;
-		byte[] size = new byte[4];
-		byte[] tmp;
-		
-		System.arraycopy(c, off, size, 0, 4);
-		s = byteArrayToInt(size);
-		tmp = new byte[s];
-		off += 4;
-		System.arraycopy(c, off, tmp, 0, s);
-		off += s;
-		u1 = new BigInteger(tmp);
-		
-		System.arraycopy(c, off, size, 0, 4);
-		s = byteArrayToInt(size);
-		tmp = new byte[s];
-		off += 4;
-		System.arraycopy(c, off, tmp, 0, s);
-		off += s;
-		u2 = new BigInteger(tmp);
-		
-		System.arraycopy(c, off, size, 0, 4);
-		s = byteArrayToInt(size);
-		tmp = new byte[s];
-		off += 4;
-		System.arraycopy(c, off, tmp, 0, s);
-		off += s;
-		e = new BigInteger(tmp);
-		
-		System.arraycopy(c, off, size, 0, 4);
-		s = byteArrayToInt(size);
-		tmp = new byte[s];
-		off += 4;
-		System.arraycopy(c, off, tmp, 0, s);
-		off += s;
-		v = new BigInteger(tmp);
-	}
-
-	public BigInteger getU1() {
-		return u1;
-	}
-
-	public void setU1(BigInteger u1) {
-		this.u1 = u1;
-	}
-
-	public BigInteger getU2() {
-		return u2;
-	}
-
-	public void setU2(BigInteger u2) {
-		this.u2 = u2;
-	}
-
-	public BigInteger getE() {
-		return e;
-	}
-
-	public void setE(BigInteger e) {
-		this.e = e;
-	}
-
-	public BigInteger getV() {
-		return v;
-	}
-
-	public void setV(BigInteger v) {
-		this.v = v;
-	}
-	
-	@Override
-	public String toString() {
-		StringBuilder result = new StringBuilder();
-		
-		result.append("u1: "+u1.toString());
-		result.append("\nu2: "+u2.toString());
-		result.append("\ne: "+e.toString());
-		result.append("\nv: "+v.toString());
-		
-		return result.toString();
-	}
-
-	/**
-	 * convert the cipher-text in a byte array,
-	 * prepending them with 4 Bytes for their length
-	 * 
-	 * @return
-	 */
-	public byte[] toByteArray(){
-		
-		byte[] u1Bytes = u1.toByteArray();
-		int u1Length = u1Bytes.length;
-		byte[] u2Bytes = u2.toByteArray();
-		int u2Length = u2Bytes.length;
-		byte[] eBytes = e.toByteArray();
-		int eLength = eBytes.length;
-		byte[] vBytes = v.toByteArray();
-		int vLength = vBytes.length;
-		
-		int off = 0;
-		byte[] result = new byte[u1Length+u2Length+eLength+vLength+4*4];
-		System.arraycopy(intToByteArray(u1Length), 0, result, 0, 4);
-		off += 4;
-		System.arraycopy(u1Bytes, 0, result, off, u1Length);
-		off += u1Length;
-		System.arraycopy(intToByteArray(u2Length), 0, result, off, 4);
-		off += 4;
-		System.arraycopy(u2Bytes, 0, result, off , u2Length);
-		off += u2Length;
-		System.arraycopy(intToByteArray(eLength), 0, result, off, 4);
-		off += 4;
-		System.arraycopy(eBytes, 0, result, off, eLength);
-		off += eLength;
-		System.arraycopy(intToByteArray(vLength), 0, result, off, 4);
-		off += 4;
-		System.arraycopy(vBytes, 0, result, off, vLength);
-		
-		return result;
-	}
-	
-	private byte[] intToByteArray(int in){
-		byte[] bytes = new byte[4];
-		for (int i = 0; i < 4; i++) {
-		    bytes[3-i] = (byte)(in >>> (i * 8));
-		}
-		return bytes;
-	}
-	
-	private int byteArrayToInt(byte[] in){
-		if (in.length != 4)
-			return -1;
-		int r = 0;
-		for (int i = 3; i >= 0; i--) {
-		    r += (int)in[i] << ((3-i) * 8);
-		}
-		return r;
-	}
+public class CramerShoupCiphertext
+{
+
+    BigInteger u1, u2, e, v;
+
+    public CramerShoupCiphertext()
+    {
+
+    }
+
+    public CramerShoupCiphertext(BigInteger u1, BigInteger u2, BigInteger e, BigInteger v)
+    {
+        this.u1 = u1;
+        this.u2 = u2;
+        this.e = e;
+        this.v = v;
+    }
+
+    public CramerShoupCiphertext(byte[] c)
+    {
+        int off = 0, s;
+        byte[] size = new byte[4];
+        byte[] tmp;
+
+        System.arraycopy(c, off, size, 0, 4);
+        s = byteArrayToInt(size);
+        tmp = new byte[s];
+        off += 4;
+        System.arraycopy(c, off, tmp, 0, s);
+        off += s;
+        u1 = new BigInteger(tmp);
+
+        System.arraycopy(c, off, size, 0, 4);
+        s = byteArrayToInt(size);
+        tmp = new byte[s];
+        off += 4;
+        System.arraycopy(c, off, tmp, 0, s);
+        off += s;
+        u2 = new BigInteger(tmp);
+
+        System.arraycopy(c, off, size, 0, 4);
+        s = byteArrayToInt(size);
+        tmp = new byte[s];
+        off += 4;
+        System.arraycopy(c, off, tmp, 0, s);
+        off += s;
+        e = new BigInteger(tmp);
+
+        System.arraycopy(c, off, size, 0, 4);
+        s = byteArrayToInt(size);
+        tmp = new byte[s];
+        off += 4;
+        System.arraycopy(c, off, tmp, 0, s);
+        off += s;
+        v = new BigInteger(tmp);
+    }
+
+    public BigInteger getU1()
+    {
+        return u1;
+    }
+
+    public void setU1(BigInteger u1)
+    {
+        this.u1 = u1;
+    }
+
+    public BigInteger getU2()
+    {
+        return u2;
+    }
+
+    public void setU2(BigInteger u2)
+    {
+        this.u2 = u2;
+    }
+
+    public BigInteger getE()
+    {
+        return e;
+    }
+
+    public void setE(BigInteger e)
+    {
+        this.e = e;
+    }
+
+    public BigInteger getV()
+    {
+        return v;
+    }
+
+    public void setV(BigInteger v)
+    {
+        this.v = v;
+    }
+
+    public String toString()
+    {
+        StringBuffer result = new StringBuffer();
+
+        result.append("u1: " + u1.toString());
+        result.append("\nu2: " + u2.toString());
+        result.append("\ne: " + e.toString());
+        result.append("\nv: " + v.toString());
+
+        return result.toString();
+    }
+
+    /**
+     * convert the cipher-text in a byte array,
+     * prepending them with 4 Bytes for their length
+     *
+     * @return
+     */
+    public byte[] toByteArray()
+    {
+
+        byte[] u1Bytes = u1.toByteArray();
+        int u1Length = u1Bytes.length;
+        byte[] u2Bytes = u2.toByteArray();
+        int u2Length = u2Bytes.length;
+        byte[] eBytes = e.toByteArray();
+        int eLength = eBytes.length;
+        byte[] vBytes = v.toByteArray();
+        int vLength = vBytes.length;
+
+        int off = 0;
+        byte[] result = new byte[u1Length + u2Length + eLength + vLength + 4 * 4];
+        System.arraycopy(intToByteArray(u1Length), 0, result, 0, 4);
+        off += 4;
+        System.arraycopy(u1Bytes, 0, result, off, u1Length);
+        off += u1Length;
+        System.arraycopy(intToByteArray(u2Length), 0, result, off, 4);
+        off += 4;
+        System.arraycopy(u2Bytes, 0, result, off, u2Length);
+        off += u2Length;
+        System.arraycopy(intToByteArray(eLength), 0, result, off, 4);
+        off += 4;
+        System.arraycopy(eBytes, 0, result, off, eLength);
+        off += eLength;
+        System.arraycopy(intToByteArray(vLength), 0, result, off, 4);
+        off += 4;
+        System.arraycopy(vBytes, 0, result, off, vLength);
+
+        return result;
+    }
+
+    private byte[] intToByteArray(int in)
+    {
+        byte[] bytes = new byte[4];
+        for (int i = 0; i < 4; i++)
+        {
+            bytes[3 - i] = (byte)(in >>> (i * 8));
+        }
+        return bytes;
+    }
+
+    private int byteArrayToInt(byte[] in)
+    {
+        if (in.length != 4)
+        {
+            return -1;
+        }
+        int r = 0;
+        for (int i = 3; i >= 0; i--)
+        {
+            r += (int)in[i] << ((3 - i) * 8);
+        }
+        return r;
+    }
 }
\ No newline at end of file
diff --git a/core/src/main/java/org/bouncycastle/crypto/engines/CramerShoupCoreEngine.java b/core/src/main/java/org/bouncycastle/crypto/engines/CramerShoupCoreEngine.java
index cc6d96be..5fcfff9b 100644
--- a/core/src/main/java/org/bouncycastle/crypto/engines/CramerShoupCoreEngine.java
+++ b/core/src/main/java/org/bouncycastle/crypto/engines/CramerShoupCoreEngine.java
@@ -13,263 +13,302 @@ import org.bouncycastle.crypto.params.ParametersWithRandom;
 import org.bouncycastle.util.BigIntegers;
 
 /**
- * 
  * Essentially the Cramer-Shoup encryption / decryption algorithms according to
  * "A practical public key cryptosystem provably secure against adaptive chosen ciphertext attack." (Crypto 1998)
- *
  */
-public class CramerShoupCoreEngine {
+public class CramerShoupCoreEngine
+{
 
-	private static final BigInteger ONE = BigInteger.ONE;
-	
-	private CramerShoupKeyParameters key;
+    private static final BigInteger ONE = BigInteger.valueOf(1);
+
+    private CramerShoupKeyParameters key;
     private SecureRandom random;
-	private boolean forEncryption;
-	private String label = null;
-
-	/**
-	 * initialise the CramerShoup engine.
-	 * 
-	 * @param forEncryption
-	 *            	whether this engine should encrypt or decrypt
-	 * @param param
-	 *            	the necessary CramerShoup key parameters.
-	 * @param label
-	 * 				the label for labelled CS as {@link String}
-	 */
-	public void init(boolean forEncryption, CipherParameters param, String label) {
-		init(forEncryption, param);
-		
-		this.label = label;
-	}
-
-	/**
-	 * initialise the CramerShoup engine.
-	 * 
-	 * @param forEncryption
-	 *            whether this engine should encrypt or decrypt
-	 * @param param
-	 *            the necessary CramerShoup key parameters.
-	 */
-	public void init(boolean forEncryption, CipherParameters param) {
+    private boolean forEncryption;
+    private String label = null;
+
+    /**
+     * initialise the CramerShoup engine.
+     *
+     * @param forEncryption whether this engine should encrypt or decrypt
+     * @param param         the necessary CramerShoup key parameters.
+     * @param label         the label for labelled CS as {@link String}
+     */
+    public void init(boolean forEncryption, CipherParameters param, String label)
+    {
+        init(forEncryption, param);
+
+        this.label = label;
+    }
+
+    /**
+     * initialise the CramerShoup engine.
+     *
+     * @param forEncryption whether this engine should encrypt or decrypt
+     * @param param         the necessary CramerShoup key parameters.
+     */
+    public void init(boolean forEncryption, CipherParameters param)
+    {
         SecureRandom providedRandom = null;
 
-		if (param instanceof ParametersWithRandom) {
-			ParametersWithRandom rParam = (ParametersWithRandom) param;
+        if (param instanceof ParametersWithRandom)
+        {
+            ParametersWithRandom rParam = (ParametersWithRandom)param;
 
-			key = (CramerShoupKeyParameters) rParam.getParameters();
+            key = (CramerShoupKeyParameters)rParam.getParameters();
             providedRandom = rParam.getRandom();
-		} else {
-			key = (CramerShoupKeyParameters) param;
-		}
+        }
+        else
+        {
+            key = (CramerShoupKeyParameters)param;
+        }
 
         this.random = initSecureRandom(forEncryption, providedRandom);
-		this.forEncryption = forEncryption;
-	}
-
-	/**
-	 * Return the maximum size for an input block to this engine. For Cramer
-	 * Shoup this is always one byte less than the key size on encryption, and
-	 * the same length as the key size on decryption.
-	 * 
-	 * @return maximum size for an input block.
-	 * 
-	 *         TODO: correct?
-	 */
-	public int getInputBlockSize() {
-		int bitSize = key.getParameters().getP().bitLength();
-
-		if (forEncryption) {
-			return (bitSize + 7) / 8 - 1;
-		} else {
-			return (bitSize + 7) / 8;
-		}
-	}
-
-	/**
-	 * Return the maximum size for an output block to this engine. For Cramer
-	 * Shoup this is always one byte less than the key size on decryption, and
-	 * the same length as the key size on encryption.
-	 * 
-	 * @return maximum size for an output block.
-	 * 
-	 *         TODO: correct?
-	 */
-	public int getOutputBlockSize() {
-		int bitSize = key.getParameters().getP().bitLength();
-
-		if (forEncryption) {
-			return (bitSize + 7) / 8;
-		} else {
-			return (bitSize + 7) / 8 - 1;
-		}
-	}
-
-	public BigInteger convertInput(byte[] in, int inOff, int inLen) {
-		if (inLen > (getInputBlockSize() + 1)) {
-			throw new DataLengthException("input too large for Cramer Shoup cipher.");
-		} else if (inLen == (getInputBlockSize() + 1) && forEncryption) {
-			throw new DataLengthException("input too large for Cramer Shoup cipher.");
-		}
-
-		byte[] block;
-
-		if (inOff != 0 || inLen != in.length) {
-			block = new byte[inLen];
-
-			System.arraycopy(in, inOff, block, 0, inLen);
-		} else {
-			block = in;
-		}
-
-		BigInteger res = new BigInteger(1, block);
-		if (res.compareTo(key.getParameters().getP()) >= 0) {
-			throw new DataLengthException("input too large for Cramer Shoup cipher.");
-		}
-
-		return res;
-	}
-
-	public byte[] convertOutput(BigInteger result) {
-		byte[] output = result.toByteArray();
-
-		if (!forEncryption) {
-			if (output[0] == 0 && output.length > getOutputBlockSize()) { // have ended up with an extra zero byte, copy down.
-				byte[] tmp = new byte[output.length - 1];
-
-				System.arraycopy(output, 1, tmp, 0, tmp.length);
-
-				return tmp;
-			}
-
-			if (output.length < getOutputBlockSize()) {// have ended up with less bytes than normal, lengthen
-				byte[] tmp = new byte[getOutputBlockSize()];
-
-				System.arraycopy(output, 0, tmp, tmp.length - output.length, output.length);
-
-				return tmp;
-			}
-		} else {
-			if (output[0] == 0) { // have ended up with an extra zero byte, copy down.
-				byte[] tmp = new byte[output.length - 1];
-
-				System.arraycopy(output, 1, tmp, 0, tmp.length);
-
-				return tmp;
-			}
-		}
-
-		return output;
-	}
-
-	public CramerShoupCiphertext encryptBlock(BigInteger input) {
-
-		CramerShoupCiphertext result = null;
-
-		if (!key.isPrivate() && this.forEncryption && key instanceof CramerShoupPublicKeyParameters) {
-			CramerShoupPublicKeyParameters pk = (CramerShoupPublicKeyParameters)key;
-			BigInteger p = pk.getParameters().getP();
-			BigInteger g1 = pk.getParameters().getG1();
-			BigInteger g2 = pk.getParameters().getG2();
-			
-			BigInteger h = pk.getH();
-
-			if (!isValidMessage(input, p))
-				return result;
-			
-			BigInteger r = generateRandomElement(p, random);
-			
-			BigInteger u1, u2, v, e, a;
-			
-			u1 = g1.modPow(r, p);
-			u2 = g2.modPow(r, p);
-			e = h.modPow(r, p).multiply(input).mod(p);
-			
-			Digest digest = pk.getParameters().getH();
-			byte[] u1Bytes = u1.toByteArray();
-			digest.update(u1Bytes, 0, u1Bytes.length);
-			byte[] u2Bytes = u2.toByteArray();
-			digest.update(u2Bytes, 0, u2Bytes.length);
-			byte[] eBytes = e.toByteArray();
-			digest.update(eBytes, 0, eBytes.length);
-			if (this.label != null){
-				byte[] lBytes = this.label.getBytes();
-				digest.update(lBytes, 0, lBytes.length);
-			}
-			byte[] out = new byte[digest.getDigestSize()];
-			digest.doFinal(out , 0);
-			a = new BigInteger(1, out);
-			
-			v = pk.getC().modPow(r, p).multiply(pk.getD().modPow(r.multiply(a), p)).mod(p);
-			
-			result = new CramerShoupCiphertext(u1, u2, e, v);
-		}
-		return result;
-	}
-	
-	public BigInteger decryptBlock(CramerShoupCiphertext input) throws CramerShoupCiphertextException {
-
-		BigInteger result = null;
-
-		if (key.isPrivate() && !this.forEncryption && key instanceof CramerShoupPrivateKeyParameters) {
-			CramerShoupPrivateKeyParameters sk = (CramerShoupPrivateKeyParameters)key;
-			
-			BigInteger p = sk.getParameters().getP();
-			
-			Digest digest = sk.getParameters().getH();
-			byte[] u1Bytes = input.getU1().toByteArray();
-			digest.update(u1Bytes, 0, u1Bytes.length);
-			byte[] u2Bytes = input.getU2().toByteArray();
-			digest.update(u2Bytes, 0, u2Bytes.length);
-			byte[] eBytes = input.getE().toByteArray();
-			digest.update(eBytes, 0, eBytes.length);
-			if (this.label != null){
-				byte[] lBytes = this.label.getBytes();
-				digest.update(lBytes, 0, lBytes.length);
-			}
-			byte[] out = new byte[digest.getDigestSize()];
-			digest.doFinal(out , 0);
-
-			BigInteger a = new BigInteger(1, out);
-			BigInteger v = input.u1.modPow(sk.getX1().add(sk.getY1().multiply(a)), p).
-					multiply(input.u2.modPow(sk.getX2().add(sk.getY2().multiply(a)), p)).mod(p);
-			
-			// check correctness of ciphertext
-			if (input.v.equals(v)){
-				result = input.e.multiply(input.u1.modPow(sk.getZ(), p).modInverse(p)).mod(p);
-			} else {
-				throw new CramerShoupCiphertextException("Sorry, that ciphertext is not correct");
-			}
-		}
-		return result;
-	}
-
-	private BigInteger generateRandomElement(BigInteger p, SecureRandom random) {
-		return BigIntegers.createRandomInRange(ONE, p.subtract(ONE), random);
-	}
-	
-	/**
-	 * just checking whether the message m is actually less than the group order p
-	 */
-	private boolean isValidMessage(BigInteger m, BigInteger p){
-		return m.compareTo(p) < 0;
-	}
+        this.forEncryption = forEncryption;
+    }
+
+    /**
+     * Return the maximum size for an input block to this engine. For Cramer
+     * Shoup this is always one byte less than the key size on encryption, and
+     * the same length as the key size on decryption.
+     *
+     * @return maximum size for an input block.
+     * <p/>
+     * TODO: correct?
+     */
+    public int getInputBlockSize()
+    {
+        int bitSize = key.getParameters().getP().bitLength();
+
+        if (forEncryption)
+        {
+            return (bitSize + 7) / 8 - 1;
+        }
+        else
+        {
+            return (bitSize + 7) / 8;
+        }
+    }
+
+    /**
+     * Return the maximum size for an output block to this engine. For Cramer
+     * Shoup this is always one byte less than the key size on decryption, and
+     * the same length as the key size on encryption.
+     *
+     * @return maximum size for an output block.
+     * <p/>
+     * TODO: correct?
+     */
+    public int getOutputBlockSize()
+    {
+        int bitSize = key.getParameters().getP().bitLength();
+
+        if (forEncryption)
+        {
+            return (bitSize + 7) / 8;
+        }
+        else
+        {
+            return (bitSize + 7) / 8 - 1;
+        }
+    }
+
+    public BigInteger convertInput(byte[] in, int inOff, int inLen)
+    {
+        if (inLen > (getInputBlockSize() + 1))
+        {
+            throw new DataLengthException("input too large for Cramer Shoup cipher.");
+        }
+        else if (inLen == (getInputBlockSize() + 1) && forEncryption)
+        {
+            throw new DataLengthException("input too large for Cramer Shoup cipher.");
+        }
+
+        byte[] block;
+
+        if (inOff != 0 || inLen != in.length)
+        {
+            block = new byte[inLen];
+
+            System.arraycopy(in, inOff, block, 0, inLen);
+        }
+        else
+        {
+            block = in;
+        }
+
+        BigInteger res = new BigInteger(1, block);
+        if (res.compareTo(key.getParameters().getP()) >= 0)
+        {
+            throw new DataLengthException("input too large for Cramer Shoup cipher.");
+        }
+
+        return res;
+    }
+
+    public byte[] convertOutput(BigInteger result)
+    {
+        byte[] output = result.toByteArray();
+
+        if (!forEncryption)
+        {
+            if (output[0] == 0 && output.length > getOutputBlockSize())
+            { // have ended up with an extra zero byte, copy down.
+                byte[] tmp = new byte[output.length - 1];
+
+                System.arraycopy(output, 1, tmp, 0, tmp.length);
+
+                return tmp;
+            }
+
+            if (output.length < getOutputBlockSize())
+            {// have ended up with less bytes than normal, lengthen
+                byte[] tmp = new byte[getOutputBlockSize()];
+
+                System.arraycopy(output, 0, tmp, tmp.length - output.length, output.length);
+
+                return tmp;
+            }
+        }
+        else
+        {
+            if (output[0] == 0)
+            { // have ended up with an extra zero byte, copy down.
+                byte[] tmp = new byte[output.length - 1];
+
+                System.arraycopy(output, 1, tmp, 0, tmp.length);
+
+                return tmp;
+            }
+        }
+
+        return output;
+    }
+
+    public CramerShoupCiphertext encryptBlock(BigInteger input)
+    {
+
+        CramerShoupCiphertext result = null;
+
+        if (!key.isPrivate() && this.forEncryption && key instanceof CramerShoupPublicKeyParameters)
+        {
+            CramerShoupPublicKeyParameters pk = (CramerShoupPublicKeyParameters)key;
+            BigInteger p = pk.getParameters().getP();
+            BigInteger g1 = pk.getParameters().getG1();
+            BigInteger g2 = pk.getParameters().getG2();
+
+            BigInteger h = pk.getH();
+
+            if (!isValidMessage(input, p))
+            {
+                return result;
+            }
+
+            BigInteger r = generateRandomElement(p, random);
+
+            BigInteger u1, u2, v, e, a;
+
+            u1 = g1.modPow(r, p);
+            u2 = g2.modPow(r, p);
+            e = h.modPow(r, p).multiply(input).mod(p);
+
+            Digest digest = pk.getParameters().getH();
+            byte[] u1Bytes = u1.toByteArray();
+            digest.update(u1Bytes, 0, u1Bytes.length);
+            byte[] u2Bytes = u2.toByteArray();
+            digest.update(u2Bytes, 0, u2Bytes.length);
+            byte[] eBytes = e.toByteArray();
+            digest.update(eBytes, 0, eBytes.length);
+            if (this.label != null)
+            {
+                byte[] lBytes = this.label.getBytes();
+                digest.update(lBytes, 0, lBytes.length);
+            }
+            byte[] out = new byte[digest.getDigestSize()];
+            digest.doFinal(out, 0);
+            a = new BigInteger(1, out);
+
+            v = pk.getC().modPow(r, p).multiply(pk.getD().modPow(r.multiply(a), p)).mod(p);
+
+            result = new CramerShoupCiphertext(u1, u2, e, v);
+        }
+        return result;
+    }
+
+    public BigInteger decryptBlock(CramerShoupCiphertext input)
+        throws CramerShoupCiphertextException
+    {
+
+        BigInteger result = null;
+
+        if (key.isPrivate() && !this.forEncryption && key instanceof CramerShoupPrivateKeyParameters)
+        {
+            CramerShoupPrivateKeyParameters sk = (CramerShoupPrivateKeyParameters)key;
+
+            BigInteger p = sk.getParameters().getP();
+
+            Digest digest = sk.getParameters().getH();
+            byte[] u1Bytes = input.getU1().toByteArray();
+            digest.update(u1Bytes, 0, u1Bytes.length);
+            byte[] u2Bytes = input.getU2().toByteArray();
+            digest.update(u2Bytes, 0, u2Bytes.length);
+            byte[] eBytes = input.getE().toByteArray();
+            digest.update(eBytes, 0, eBytes.length);
+            if (this.label != null)
+            {
+                byte[] lBytes = this.label.getBytes();
+                digest.update(lBytes, 0, lBytes.length);
+            }
+            byte[] out = new byte[digest.getDigestSize()];
+            digest.doFinal(out, 0);
+
+            BigInteger a = new BigInteger(1, out);
+            BigInteger v = input.u1.modPow(sk.getX1().add(sk.getY1().multiply(a)), p).
+                multiply(input.u2.modPow(sk.getX2().add(sk.getY2().multiply(a)), p)).mod(p);
+
+            // check correctness of ciphertext
+            if (input.v.equals(v))
+            {
+                result = input.e.multiply(input.u1.modPow(sk.getZ(), p).modInverse(p)).mod(p);
+            }
+            else
+            {
+                throw new CramerShoupCiphertextException("Sorry, that ciphertext is not correct");
+            }
+        }
+        return result;
+    }
+
+    private BigInteger generateRandomElement(BigInteger p, SecureRandom random)
+    {
+        return BigIntegers.createRandomInRange(ONE, p.subtract(ONE), random);
+    }
+
+    /**
+     * just checking whether the message m is actually less than the group order p
+     */
+    private boolean isValidMessage(BigInteger m, BigInteger p)
+    {
+        return m.compareTo(p) < 0;
+    }
 
     protected SecureRandom initSecureRandom(boolean needed, SecureRandom provided)
     {
         return !needed ? null : (provided != null) ? provided : new SecureRandom();
     }
 
-	/**
-	 *	CS exception for wrong cipher-texts 
-	 */
-	public class CramerShoupCiphertextException extends Exception {
-		
-		private static final long serialVersionUID = -6360977166495345076L;
-
-		public CramerShoupCiphertextException(String msg) {
-			super(msg);
-		}
-		
-	}
+    /**
+     * CS exception for wrong cipher-texts
+     */
+    public class CramerShoupCiphertextException
+        extends Exception
+    {
+
+        private static final long serialVersionUID = -6360977166495345076L;
+
+        public CramerShoupCiphertextException(String msg)
+        {
+            super(msg);
+        }
+
+    }
 }
diff --git a/core/src/test/java/org/bouncycastle/crypto/test/CramerShoupTest.java b/core/src/test/java/org/bouncycastle/crypto/test/CramerShoupTest.java
index 2eb90152..e9633572 100644
--- a/core/src/test/java/org/bouncycastle/crypto/test/CramerShoupTest.java
+++ b/core/src/test/java/org/bouncycastle/crypto/test/CramerShoupTest.java
@@ -15,106 +15,133 @@ import org.bouncycastle.crypto.params.CramerShoupParameters;
 import org.bouncycastle.util.BigIntegers;
 import org.bouncycastle.util.test.SimpleTest;
 
-public class CramerShoupTest extends SimpleTest {
+public class CramerShoupTest
+    extends SimpleTest
+{
+    private static final BigInteger ONE = BigInteger.valueOf(1);
 
     private static final SecureRandom RND = new SecureRandom();
 
-	private AsymmetricCipherKeyPair keyPair;
-
-	public static void main(String[] args) {
-		runTest(new CramerShoupTest());
-	}
-
-	@Override
-	public String getName() {
-		return "CramerShoup";
-	}
-
-	@Override
-	public void performTest() throws Exception {
-        BigInteger pSubOne = DHStandardGroups.rfc3526_2048.getP().subtract(BigInteger.ONE);
-	    for (int i = 0; i < 10; ++i) {
-            BigInteger message = BigIntegers.createRandomInRange(BigInteger.ONE, pSubOne, RND);
-
-			BigInteger m1 = encDecTest(message);
-			BigInteger m2 = labelledEncDecTest(message, "myRandomLabel");
-			BigInteger m3 = encDecEncodingTest(message);
-			BigInteger m4 = labelledEncDecEncodingTest(message, "myOtherCoolLabel");
-
-			if (!message.equals(m1) || !message.equals(m2) || !message.equals(m3) || !message.equals(m4)){
-				fail("decrypted message != original message");
-			}
-		}
-	}
-	
-	private BigInteger encDecEncodingTest(BigInteger m){
-		CramerShoupCiphertext ciphertext = encrypt(m);
-		byte[] c = ciphertext.toByteArray();
-		CramerShoupCiphertext decC = new CramerShoupCiphertext(c);
-		return decrypt(decC);
-	}
-	
-	private BigInteger labelledEncDecEncodingTest(BigInteger m, String l){
-		byte[] c = encrypt(m, l).toByteArray();
-		return decrypt(new CramerShoupCiphertext(c), l);
-	}
-	
-	private BigInteger encDecTest(BigInteger m){
-		CramerShoupCiphertext c = encrypt(m);
-		return decrypt(c);
-	}
-	
-	private BigInteger labelledEncDecTest(BigInteger m, String l){
-		CramerShoupCiphertext c = encrypt(m, l);
-		return decrypt(c, l);
-	}
-
-	
-	private BigInteger decrypt(CramerShoupCiphertext ciphertext) {
-		return decrypt(ciphertext, null);
-	}
-	
-	private BigInteger decrypt(CramerShoupCiphertext ciphertext, String label) {
-		
-		CramerShoupCoreEngine engine = new CramerShoupCoreEngine();
-		if (label != null)
-			engine.init(false, keyPair.getPrivate(), label);
-		else
-			engine.init(false, keyPair.getPrivate());
-		try {
-			BigInteger m = engine.decryptBlock(ciphertext);
-			
-			return m;
-		} catch (CramerShoupCiphertextException e) {
-			e.printStackTrace();
-		}
-		
-		return null;
-	}
-
-	private CramerShoupCiphertext encrypt(BigInteger message) {
-		return encrypt(message, null);
-	}
-	
-	private CramerShoupCiphertext encrypt(BigInteger message, String label) {
-		CramerShoupKeyPairGenerator kpGen = new CramerShoupKeyPairGenerator();
-		CramerShoupParametersGenerator pGen = new CramerShoupParametersGenerator();
-		
-		pGen.init(2048, 1, RND);
-		CramerShoupParameters params = pGen.generateParameters(DHStandardGroups.rfc3526_2048);
-		CramerShoupKeyGenerationParameters param = new CramerShoupKeyGenerationParameters(RND, params);
-
-		kpGen.init(param);
-		keyPair = kpGen.generateKeyPair();
-		
-		CramerShoupCoreEngine engine = new CramerShoupCoreEngine();
-		if (label != null)
-			engine.init(true, keyPair.getPublic(), label);
-		else
-			engine.init(true, keyPair.getPublic());
-		
-		CramerShoupCiphertext ciphertext = engine.encryptBlock(message);
-		
-		return ciphertext;
-	}
+    private AsymmetricCipherKeyPair keyPair;
+
+    public static void main(String[] args)
+    {
+        runTest(new CramerShoupTest());
+    }
+
+    public String getName()
+    {
+        return "CramerShoup";
+    }
+
+
+    public void performTest()
+        throws Exception
+    {
+        BigInteger pSubOne = DHStandardGroups.rfc3526_2048.getP().subtract(ONE);
+        for (int i = 0; i < 10; ++i)
+        {
+            BigInteger message = BigIntegers.createRandomInRange(ONE, pSubOne, RND);
+
+            BigInteger m1 = encDecTest(message);
+            BigInteger m2 = labelledEncDecTest(message, "myRandomLabel");
+            BigInteger m3 = encDecEncodingTest(message);
+            BigInteger m4 = labelledEncDecEncodingTest(message, "myOtherCoolLabel");
+
+            if (!message.equals(m1) || !message.equals(m2) || !message.equals(m3) || !message.equals(m4))
+            {
+                fail("decrypted message != original message");
+            }
+        }
+    }
+
+    private BigInteger encDecEncodingTest(BigInteger m)
+    {
+        CramerShoupCiphertext ciphertext = encrypt(m);
+        byte[] c = ciphertext.toByteArray();
+        CramerShoupCiphertext decC = new CramerShoupCiphertext(c);
+        return decrypt(decC);
+    }
+
+    private BigInteger labelledEncDecEncodingTest(BigInteger m, String l)
+    {
+        byte[] c = encrypt(m, l).toByteArray();
+        return decrypt(new CramerShoupCiphertext(c), l);
+    }
+
+    private BigInteger encDecTest(BigInteger m)
+    {
+        CramerShoupCiphertext c = encrypt(m);
+        return decrypt(c);
+    }
+
+    private BigInteger labelledEncDecTest(BigInteger m, String l)
+    {
+        CramerShoupCiphertext c = encrypt(m, l);
+        return decrypt(c, l);
+    }
+
+
+    private BigInteger decrypt(CramerShoupCiphertext ciphertext)
+    {
+        return decrypt(ciphertext, null);
+    }
+
+    private BigInteger decrypt(CramerShoupCiphertext ciphertext, String label)
+    {
+
+        CramerShoupCoreEngine engine = new CramerShoupCoreEngine();
+        if (label != null)
+        {
+            engine.init(false, keyPair.getPrivate(), label);
+        }
+        else
+        {
+            engine.init(false, keyPair.getPrivate());
+        }
+        try
+        {
+            BigInteger m = engine.decryptBlock(ciphertext);
+
+            return m;
+        }
+        catch (CramerShoupCiphertextException e)
+        {
+            e.printStackTrace();
+        }
+
+        return null;
+    }
+
+    private CramerShoupCiphertext encrypt(BigInteger message)
+    {
+        return encrypt(message, null);
+    }
+
+    private CramerShoupCiphertext encrypt(BigInteger message, String label)
+    {
+        CramerShoupKeyPairGenerator kpGen = new CramerShoupKeyPairGenerator();
+        CramerShoupParametersGenerator pGen = new CramerShoupParametersGenerator();
+
+        pGen.init(2048, 1, RND);
+        CramerShoupParameters params = pGen.generateParameters(DHStandardGroups.rfc3526_2048);
+        CramerShoupKeyGenerationParameters param = new CramerShoupKeyGenerationParameters(RND, params);
+
+        kpGen.init(param);
+        keyPair = kpGen.generateKeyPair();
+
+        CramerShoupCoreEngine engine = new CramerShoupCoreEngine();
+        if (label != null)
+        {
+            engine.init(true, keyPair.getPublic(), label);
+        }
+        else
+        {
+            engine.init(true, keyPair.getPublic());
+        }
+
+        CramerShoupCiphertext ciphertext = engine.encryptBlock(message);
+
+        return ciphertext;
+    }
 }