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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;
}
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;
}
}
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