package org.spongycastle.crypto.engines;
import org.spongycastle.crypto.BlockCipher;
import org.spongycastle.crypto.CipherParameters;
import org.spongycastle.crypto.DataLengthException;
import org.spongycastle.crypto.params.KeyParameter;
/**
* A Noekeon engine, using direct-key mode.
*/
public class NoekeonEngine
implements BlockCipher
{
private static final int genericSize = 16; // Block and key size, as well as the amount of rounds.
private static final int[] nullVector =
{
0x00, 0x00, 0x00, 0x00 // Used in decryption
},
roundConstants =
{
0x80, 0x1b, 0x36, 0x6c,
0xd8, 0xab, 0x4d, 0x9a,
0x2f, 0x5e, 0xbc, 0x63,
0xc6, 0x97, 0x35, 0x6a,
0xd4
};
private int[] state = new int[4], // a
subKeys = new int[4], // k
decryptKeys = new int[4];
private boolean _initialised,
_forEncryption;
/**
* Create an instance of the Noekeon encryption algorithm
* and set some defaults
*/
public NoekeonEngine()
{
_initialised = false;
}
public String getAlgorithmName()
{
return "Noekeon";
}
public int getBlockSize()
{
return genericSize;
}
/**
* initialise
*
* @param forEncryption whether or not we are for encryption.
* @param params the parameters required to set up the cipher.
* @exception IllegalArgumentException if the params argument is
* inappropriate.
*/
public void init(
boolean forEncryption,
CipherParameters params)
{
if (!(params instanceof KeyParameter))
{
throw new IllegalArgumentException("invalid parameter passed to Noekeon init - " + params.getClass().getName());
}
_forEncryption = forEncryption;
_initialised = true;
KeyParameter p = (KeyParameter)params;
setKey(p.getKey());
}
public int processBlock(
byte[] in,
int inOff,
byte[] out,
int outOff)
{
if (!_initialised)
{
throw new IllegalStateException(getAlgorithmName()+" not initialised");
}
if ((inOff + genericSize) > in.length)
{
throw new DataLengthException("input buffer too short");
}
if ((outOff + genericSize) > out.length)
{
throw new DataLengthException("output buffer too short");
}
return (_forEncryption) ? encryptBlock(in, inOff, out, outOff)
: decryptBlock(in, inOff, out, outOff);
}
public void reset()
{
}
/**
* Re-key the cipher.
* <p>
* @param key the key to be used
*/
private void setKey(
byte[] key)
{
subKeys[0] = bytesToIntBig(key, 0);
subKeys[1] = bytesToIntBig(key, 4);
subKeys[2] = bytesToIntBig(key, 8);
subKeys[3] = bytesToIntBig(key, 12);
}
private int encryptBlock(
byte[] in,
int inOff,
byte[] out,
int outOff)
{
state[0] = bytesToIntBig(in, inOff);
state[1] = bytesToIntBig(in, inOff+4);
state[2] = bytesToIntBig(in, inOff+8);
state[3] = bytesToIntBig(in, inOff+12);
int i;
for (i = 0; i < genericSize; i++)
{
state[0] ^= roundConstants[i];
theta(state, subKeys);
pi1(state);
gamma(state);
pi2(state);
}
state[0] ^= roundConstants[i];
theta(state, subKeys);
intToBytesBig(state[0], out, outOff);
intToBytesBig(state[1], out, outOff+4);
intToBytesBig(state[2], out, outOff+8);
intToBytesBig(state[3], out, outOff+12);
return genericSize;
}
private int decryptBlock(
byte[] in,
int inOff,
byte[] out,
int outOff)
{
state[0] = bytesToIntBig(in, inOff);
state[1] = bytesToIntBig(in, inOff+4);
state[2] = bytesToIntBig(in, inOff+8);
state[3] = bytesToIntBig(in, inOff+12);
System.arraycopy(subKeys, 0, decryptKeys, 0, subKeys.length);
theta(decryptKeys, nullVector);
int i;
for (i = genericSize; i > 0; i--)
{
theta(state, decryptKeys);
state[0] ^= roundConstants[i];
pi1(state);
gamma(state);
pi2(state);
}
theta(state, decryptKeys);
state[0] ^= roundConstants[i];
intToBytesBig(state[0], out, outOff);
intToBytesBig(state[1], out, outOff+4);
intToBytesBig(state[2], out, outOff+8);
intToBytesBig(state[3], out, outOff+12);
return genericSize;
}
private void gamma(int[] a)
{
a[1] ^= ~a[3] & ~a[2];
a[0] ^= a[2] & a[1];
int tmp = a[3];
a[3] = a[0];
a[0] = tmp;
a[2] ^= a[0]^a[1]^a[3];
a[1] ^= ~a[3] & ~a[2];
a[0] ^= a[2] & a[1];
}
private void theta(int[] a, int[] k)
{
int tmp;
tmp = a[0]^a[2];
tmp ^= rotl(tmp,8)^rotl(tmp,24);
a[1] ^= tmp;
a[3] ^= tmp;
for (int i = 0; i < 4; i++)
{
a[i] ^= k[i];
}
tmp = a[1]^a[3];
tmp ^= rotl(tmp,8)^rotl(tmp,24);
a[0] ^= tmp;
a[2] ^= tmp;
}
private void pi1(int[] a)
{
a[1] = rotl(a[1], 1);
a[2] = rotl(a[2], 5);
a[3] = rotl(a[3], 2);
}
private void pi2(int[] a)
{
a[1] = rotl(a[1], 31);
a[2] = rotl(a[2], 27);
a[3] = rotl(a[3], 30);
}
// Helpers
private int bytesToIntBig(byte[] in, int off)
{
return ((in[off++]) << 24) |
((in[off++] & 0xff) << 16) |
((in[off++] & 0xff) << 8) |
(in[off ] & 0xff);
}
private void intToBytesBig(int x, byte[] out, int off)
{
out[off++] = (byte)(x >>> 24);
out[off++] = (byte)(x >>> 16);
out[off++] = (byte)(x >>> 8);
out[off ] = (byte)x;
}
private int rotl(int x, int y)
{
return (x << y) | (x >>> (32-y));
}
}