serpentengine.java

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package org.bouncycastle.crypto.engines;

import org.bouncycastle.crypto.BlockCipher;
import org.bouncycastle.crypto.CipherParameters;
import org.bouncycastle.crypto.DataLengthException;
import org.bouncycastle.crypto.params.KeyParameter;

/**
 * Serpent is a 128-bit 32-round block cipher with variable key lengths,
 * including 128, 192 and 256 bit keys conjectured to be at least as
 * secure as three-key triple-DES.
 * <p>
 * Serpent was designed by Ross Anderson, Eli Biham and Lars Knudsen as a
 * candidate algorithm for the NIST AES Quest.>
 * <p>
 * For full details see the <a href="http://www.cl.cam.ac.uk/~rja14/serpent.html">The Serpent home page</a>
 */
public class SerpentEngine
    implements BlockCipher
{
    private static final int    BLOCK_SIZE = 16;

    static final int ROUNDS = 32;
    static final int PHI    = 0x9E3779B9;       // (sqrt(5) - 1) * 2**31

    private boolean        encrypting;
    private int[]          wKey;

    private int           X0, X1, X2, X3;    // registers

    /**
     * initialise a Serpent cipher.
     *
     * @param encrypting 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             encrypting,
        CipherParameters    params)
    {
        if (params instanceof KeyParameter)
        {
            this.encrypting = encrypting;
            this.wKey = makeWorkingKey(((KeyParameter)params).getKey());
            return;
        }

        throw new IllegalArgumentException("invalid parameter passed to Serpent init - " + params.getClass().getName());
    }

    public String getAlgorithmName()
    {
        return "Serpent";
    }

    public int getBlockSize()
    {
        return BLOCK_SIZE;
    }

    /**
     * Process one block of input from the array in and write it to
     * the out array.
     *
     * @param in the array containing the input data.
     * @param inOff offset into the in array the data starts at.
     * @param out the array the output data will be copied into.
     * @param outOff the offset into the out array the output will start at.
     * @exception DataLengthException if there isn't enough data in in, or
     * space in out.
     * @exception IllegalStateException if the cipher isn't initialised.
     * @return the number of bytes processed and produced.
     */
    public final int processBlock(
        byte[]  in,
        int     inOff,
        byte[]  out,
        int     outOff)
    {
        if (wKey == null)
        {
            throw new IllegalStateException("Serpent not initialised");
        }

        if ((inOff + BLOCK_SIZE) > in.length)
        {
            throw new DataLengthException("input buffer too short");
        }

        if ((outOff + BLOCK_SIZE) > out.length)
        {
            throw new DataLengthException("output buffer too short");
        }

        if (encrypting)
        {
            encryptBlock(in, inOff, out, outOff);
        }
        else
        {
            decryptBlock(in, inOff, out, outOff);
        }

        return BLOCK_SIZE;
    }

    public void reset()
    {
    }

    /**
     * Expand a user-supplied key material into a session key.
     *
     * @param key  The user-key bytes (multiples of 4) to use.
     * @exception IllegalArgumentException
     */
    private int[] makeWorkingKey(
        byte[] key)
    throws  IllegalArgumentException
    {
        //
        // pad key to 256 bits
        //
        int[]   kPad = new int[16];
        int     off = 0;
        int     length = 0;

        for (off = key.length - 4; off > 0; off -= 4)
        {
            kPad[length++] = bytesToWord(key, off);
        }

        if (off == 0)
        {
            kPad[length++] = bytesToWord(key, 0);
            if (length < 8)
            {
                kPad[length] = 1;
            }
        }
        else
        {
            throw new IllegalArgumentException("key must be a multiple of 4 bytes");
        }

        //
        // expand the padded key up to 33 x 128 bits of key material
        //
        int     amount = (ROUNDS + 1) * 4;
        int[]   w = new int[amount];

        //
        // compute w0 to w7 from w-8 to w-1
        //
        for (int i = 8; i < 16; i++)
        {
            kPad[i] = rotateLeft(kPad[i - 8] ^ kPad[i - 5] ^ kPad[i - 3] ^ kPad[i - 1] ^ PHI ^ (i - 8), 11);
        }

        System.arraycopy(kPad, 8, w, 0, 8);

        //
        // compute w8 to w136
        //
        for (int i = 8; i < amount; i++)
        {
            w[i] = rotateLeft(w[i - 8] ^ w[i - 5] ^ w[i - 3] ^ w[i - 1] ^ PHI ^ i, 11);
        }

        //
        // create the working keys by processing w with the Sbox and IP
        //
        sb3(w[0], w[1], w[2], w[3]);
        w[0] = X0; w[1] = X1; w[2] = X2; w[3] = X3; 
        sb2(w[4], w[5], w[6], w[7]);
        w[4] = X0; w[5] = X1; w[6] = X2; w[7] = X3; 
        sb1(w[8], w[9], w[10], w[11]);
        w[8] = X0; w[9] = X1; w[10] = X2; w[11] = X3; 
        sb0(w[12], w[13], w[14], w[15]);
        w[12] = X0; w[13] = X1; w[14] = X2; w[15] = X3; 
        sb7(w[16], w[17], w[18], w[19]);
        w[16] = X0; w[17] = X1; w[18] = X2; w[19] = X3; 
        sb6(w[20], w[21], w[22], w[23]);
        w[20] = X0; w[21] = X1; w[22] = X2; w[23] = X3; 
        sb5(w[24], w[25], w[26], w[27]);
        w[24] = X0; w[25] = X1; w[26] = X2; w[27] = X3; 
        sb4(w[28], w[29], w[30], w[31]);
        w[28] = X0; w[29] = X1; w[30] = X2; w[31] = X3; 
        sb3(w[32], w[33], w[34], w[35]);
        w[32] = X0; w[33] = X1; w[34] = X2; w[35] = X3; 
        sb2(w[36], w[37], w[38], w[39]);
        w[36] = X0; w[37] = X1; w[38] = X2; w[39] = X3; 
        sb1(w[40], w[41], w[42], w[43]);
        w[40] = X0; w[41] = X1; w[42] = X2; w[43] = X3; 
        sb0(w[44], w[45], w[46], w[47]);
        w[44] = X0; w[45] = X1; w[46] = X2; w[47] = X3; 
        sb7(w[48], w[49], w[50], w[51]);
        w[48] = X0; w[49] = X1; w[50] = X2; w[51] = X3; 
        sb6(w[52], w[53], w[54], w[55]);
        w[52] = X0; w[53] = X1; w[54] = X2; w[55] = X3; 
        sb5(w[56], w[57], w[58], w[59]);
        w[56] = X0; w[57] = X1; w[58] = X2; w[59] = X3; 
        sb4(w[60], w[61], w[62], w[63]);
        w[60] = X0; w[61] = X1; w[62] = X2; w[63] = X3; 
        sb3(w[64], w[65], w[66], w[67]);
        w[64] = X0; w[65] = X1; w[66] = X2; w[67] = X3; 
        sb2(w[68], w[69], w[70], w[71]);
        w[68] = X0; w[69] = X1; w[70] = X2; w[71] = X3; 
        sb1(w[72], w[73], w[74], w[75]);
        w[72] = X0; w[73] = X1; w[74] = X2; w[75] = X3; 
        sb0(w[76], w[77], w[78], w[79]);
        w[76] = X0; w[77] = X1; w[78] = X2; w[79] = X3; 
        sb7(w[80], w[81], w[82], w[83]);
        w[80] = X0; w[81] = X1; w[82] = X2; w[83] = X3; 
        sb6(w[84], w[85], w[86], w[87]);
        w[84] = X0; w[85] = X1; w[86] = X2; w[87] = X3; 
        sb5(w[88], w[89], w[90], w[91]);
        w[88] = X0; w[89] = X1; w[90] = X2; w[91] = X3; 
        sb4(w[92], w[93], w[94], w[95]);
        w[92] = X0; w[93] = X1; w[94] = X2; w[95] = X3; 
        sb3(w[96], w[97], w[98], w[99]);
        w[96] = X0; w[97] = X1; w[98] = X2; w[99] = X3; 
        sb2(w[100], w[101], w[102], w[103]);
        w[100] = X0; w[101] = X1; w[102] = X2; w[103] = X3; 
        sb1(w[104], w[105], w[106], w[107]);
        w[104] = X0; w[105] = X1; w[106] = X2; w[107] = X3; 
        sb0(w[108], w[109], w[110], w[111]);
        w[108] = X0; w[109] = X1; w[110] = X2; w[111] = X3; 
        sb7(w[112], w[113], w[114], w[115]);
        w[112] = X0; w[113] = X1; w[114] = X2; w[115] = X3; 
        sb6(w[116], w[117], w[118], w[119]);
        w[116] = X0; w[117] = X1; w[118] = X2; w[119] = X3; 
        sb5(w[120], w[121], w[122], w[123]);
        w[120] = X0; w[121] = X1; w[122] = X2; w[123] = X3; 
        sb4(w[124], w[125], w[126], w[127]);
        w[124] = X0; w[125] = X1; w[126] = X2; w[127] = X3; 
        sb3(w[128], w[129], w[130], w[131]);
        w[128] = X0; w[129] = X1; w[130] = X2; w[131] = X3; 

        return w;
    }

    private int rotateLeft(
        int     x,
        int     bits)
    {
        return (x << bits) | (x >>> -bits);
    }

    private int rotateRight(
        int     x,
        int     bits)
    {
        return (x >>> bits) | (x << -bits);
    }

    private int bytesToWord(
        byte[]  src,
        int     srcOff)
    {
        return (((src[srcOff] & 0xff) << 24) | ((src[srcOff + 1] & 0xff) <<  16) |
          ((src[srcOff + 2] & 0xff) << 8) | ((src[srcOff + 3] & 0xff)));
    }

    private void wordToBytes(
        int     word,
        byte[]  dst,
        int     dstOff)
    {
        dst[dstOff + 3] = (byte)(word);
        dst[dstOff + 2] = (byte)(word >>> 8);
        dst[dstOff + 1] = (byte)(word >>> 16);
        dst[dstOff]     = (byte)(word >>> 24);
    }

    /**
     * Encrypt one block of plaintext.
     *
     * @param in the array containing the input data.
     * @param inOff offset into the in array the data starts at.
     * @param out the array the output data will be copied into.
     * @param outOff the offset into the out array the output will start at.
     */
    private void encryptBlock(
        byte[]  in,
        int     inOff,
        byte[]  out,
        int     outOff)
    {
        X3 = bytesToWord(in, inOff);
        X2 = bytesToWord(in, inOff + 4);
        X1 = bytesToWord(in, inOff + 8);
        X0 = bytesToWord(in, inOff + 12);

        sb0(wKey[0] ^ X0, wKey[1] ^ X1, wKey[2] ^ X2, wKey[3] ^ X3); LT();
        sb1(wKey[4] ^ X0, wKey[5] ^ X1, wKey[6] ^ X2, wKey[7] ^ X3); LT();
        sb2(wKey[8] ^ X0, wKey[9] ^ X1, wKey[10] ^ X2, wKey[11] ^ X3); LT();
        sb3(wKey[12] ^ X0, wKey[13] ^ X1, wKey[14] ^ X2, wKey[15] ^ X3); LT();
        sb4(wKey[16] ^ X0, wKey[17] ^ X1, wKey[18] ^ X2, wKey[19] ^ X3); LT();
        sb5(wKey[20] ^ X0, wKey[21] ^ X1, wKey[22] ^ X2, wKey[23] ^ X3); LT();
        sb6(wKey[24] ^ X0, wKey[25] ^ X1, wKey[26] ^ X2, wKey[27] ^ X3); LT();
        sb7(wKey[28] ^ X0, wKey[29] ^ X1, wKey[30] ^ X2, wKey[31] ^ X3); LT();
        sb0(wKey[32] ^ X0, wKey[33] ^ X1, wKey[34] ^ X2, wKey[35] ^ X3); LT();
        sb1(wKey[36] ^ X0, wKey[37] ^ X1, wKey[38] ^ X2, wKey[39] ^ X3); LT();
        sb2(wKey[40] ^ X0, wKey[41] ^ X1, wKey[42] ^ X2, wKey[43] ^ X3); LT();
        sb3(wKey[44] ^ X0, wKey[45] ^ X1, wKey[46] ^ X2, wKey[47] ^ X3); LT();
        sb4(wKey[48] ^ X0, wKey[49] ^ X1, wKey[50] ^ X2, wKey[51] ^ X3); LT();
        sb5(wKey[52] ^ X0, wKey[53] ^ X1, wKey[54] ^ X2, wKey[55] ^ X3); LT();
        sb6(wKey[56] ^ X0, wKey[57] ^ X1, wKey[58] ^ X2, wKey[59] ^ X3); LT();
        sb7(wKey[60] ^ X0, wKey[61] ^ X1, wKey[62] ^ X2, wKey[63] ^ X3); LT();
        sb0(wKey[64] ^ X0, wKey[65] ^ X1, wKey[66] ^ X2, wKey[67] ^ X3); LT();
        sb1(wKey[68] ^ X0, wKey[69] ^ X1, wKey[70] ^ X2, wKey[71] ^ X3); LT();
        sb2(wKey[72] ^ X0, wKey[73] ^ X1, wKey[74] ^ X2, wKey[75] ^ X3); LT();
        sb3(wKey[76] ^ X0, wKey[77] ^ X1, wKey[78] ^ X2, wKey[79] ^ X3); LT();
        sb4(wKey[80] ^ X0, wKey[81] ^ X1, wKey[82] ^ X2, wKey[83] ^ X3); LT();
        sb5(wKey[84] ^ X0, wKey[85] ^ X1, wKey[86] ^ X2, wKey[87] ^ X3); LT();
        sb6(wKey[88] ^ X0, wKey[89] ^ X1, wKey[90] ^ X2, wKey[91] ^ X3); LT();
        sb7(wKey[92] ^ X0, wKey[93] ^ X1, wKey[94] ^ X2, wKey[95] ^ X3); LT();
        sb0(wKey[96] ^ X0, wKey[97] ^ X1, wKey[98] ^ X2, wKey[99] ^ X3); LT();
        sb1(wKey[100] ^ X0, wKey[101] ^ X1, wKey[102] ^ X2, wKey[103] ^ X3); LT();
        sb2(wKey[104] ^ X0, wKey[105] ^ X1, wKey[106] ^ X2, wKey[107] ^ X3); LT();
        sb3(wKey[108] ^ X0, wKey[109] ^ X1, wKey[110] ^ X2, wKey[111] ^ X3); LT();
        sb4(wKey[112] ^ X0, wKey[113] ^ X1, wKey[114] ^ X2, wKey[115] ^ X3); LT();
        sb5(wKey[116] ^ X0, wKey[117] ^ X1, wKey[118] ^ X2, wKey[119] ^ X3); LT();
        sb6(wKey[120] ^ X0, wKey[121] ^ X1, wKey[122] ^ X2, wKey[123] ^ X3); LT();
        sb7(wKey[124] ^ X0, wKey[125] ^ X1, wKey[126] ^ X2, wKey[127] ^ X3);

        wordToBytes(wKey[131] ^ X3, out, outOff);
        wordToBytes(wKey[130] ^ X2, out, outOff + 4);
        wordToBytes(wKey[129] ^ X1, out, outOff + 8);
        wordToBytes(wKey[128] ^ X0, out, outOff + 12);
    }

    /**
     * Decrypt one block of ciphertext.
     *
     * @param in the array containing the input data.
     * @param inOff offset into the in array the data starts at.
     * @param out the array the output data will be copied into.
     * @param outOff the offset into the out array the output will start at.
     */
    private void decryptBlock(
        byte[]  in,
        int     inOff,
        byte[]  out,
        int     outOff)
    {
        X3 = wKey[131] ^ bytesToWord(in, inOff);
        X2 = wKey[130] ^ bytesToWord(in, inOff + 4);
        X1 = wKey[129] ^ bytesToWord(in, inOff + 8);
        X0 = wKey[128] ^ bytesToWord(in, inOff + 12);

        ib7(X0, X1, X2, X3);
        X0 ^= wKey[124]; X1 ^= wKey[125]; X2 ^= wKey[126]; X3 ^= wKey[127];
        inverseLT(); ib6(X0, X1, X2, X3);
        X0 ^= wKey[120]; X1 ^= wKey[121]; X2 ^= wKey[122]; X3 ^= wKey[123];
        inverseLT(); ib5(X0, X1, X2, X3);
        X0 ^= wKey[116]; X1 ^= wKey[117]; X2 ^= wKey[118]; X3 ^= wKey[119];
        inverseLT(); ib4(X0, X1, X2, X3);
        X0 ^= wKey[112]; X1 ^= wKey[113]; X2 ^= wKey[114]; X3 ^= wKey[115];
        inverseLT(); ib3(X0, X1, X2, X3);
        X0 ^= wKey[108]; X1 ^= wKey[109]; X2 ^= wKey[110]; X3 ^= wKey[111];
        inverseLT(); ib2(X0, X1, X2, X3);
        X0 ^= wKey[104]; X1 ^= wKey[105]; X2 ^= wKey[106]; X3 ^= wKey[107];
        inverseLT(); ib1(X0, X1, X2, X3);
        X0 ^= wKey[100]; X1 ^= wKey[101]; X2 ^= wKey[102]; X3 ^= wKey[103];
        inverseLT(); ib0(X0, X1, X2, X3);
        X0 ^= wKey[96]; X1 ^= wKey[97]; X2 ^= wKey[98]; X3 ^= wKey[99];
        inverseLT(); ib7(X0, X1, X2, X3);
        X0 ^= wKey[92]; X1 ^= wKey[93]; X2 ^= wKey[94]; X3 ^= wKey[95];
        inverseLT(); ib6(X0, X1, X2, X3);
        X0 ^= wKey[88]; X1 ^= wKey[89]; X2 ^= wKey[90]; X3 ^= wKey[91];
        inverseLT(); ib5(X0, X1, X2, X3);
        X0 ^= wKey[84]; X1 ^= wKey[85]; X2 ^= wKey[86]; X3 ^= wKey[87];
        inverseLT(); ib4(X0, X1, X2, X3);
        X0 ^= wKey[80]; X1 ^= wKey[81]; X2 ^= wKey[82]; X3 ^= wKey[83];
        inverseLT(); ib3(X0, X1, X2, X3);
        X0 ^= wKey[76]; X1 ^= wKey[77]; X2 ^= wKey[78]; X3 ^= wKey[79];
        inverseLT(); ib2(X0, X1, X2, X3);
        X0 ^= wKey[72]; X1 ^= wKey[73]; X2 ^= wKey[74]; X3 ^= wKey[75];
        inverseLT(); ib1(X0, X1, X2, X3);
        X0 ^= wKey[68]; X1 ^= wKey[69]; X2 ^= wKey[70]; X3 ^= wKey[71];
        inverseLT(); ib0(X0, X1, X2, X3);
        X0 ^= wKey[64]; X1 ^= wKey[65]; X2 ^= wKey[66]; X3 ^= wKey[67];
        inverseLT(); ib7(X0, X1, X2, X3);
        X0 ^= wKey[60]; X1 ^= wKey[61]; X2 ^= wKey[62]; X3 ^= wKey[63];
        inverseLT(); ib6(X0, X1, X2, X3);
        X0 ^= wKey[56]; X1 ^= wKey[57]; X2 ^= wKey[58]; X3 ^= wKey[59];
        inverseLT(); ib5(X0, X1, X2, X3);
        X0 ^= wKey[52]; X1 ^= wKey[53]; X2 ^= wKey[54]; X3 ^= wKey[55];