aesfastengine.java

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        return W;
    }

    private int         ROUNDS;
    private int[][]     WorkingKey = null;
    private int         C0, C1, C2, C3;
    private boolean     forEncryption;

    private static final int BLOCK_SIZE = 16;

    /**
     * default constructor - 128 bit block size.
     */
    public AESFastEngine()
    {
    }

    /**
     * initialise an AES cipher.
     *
     * @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)
        {
            WorkingKey = generateWorkingKey(((KeyParameter)params).getKey(), forEncryption);
            this.forEncryption = forEncryption;
            return;
        }

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

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

    public int getBlockSize()
    {
        return BLOCK_SIZE;
    }

    public int processBlock(
        byte[] in,
        int inOff,
        byte[] out,
        int outOff)
    {
        if (WorkingKey == null)
        {
            throw new IllegalStateException("AES engine not initialised");
        }

        if ((inOff + (32 / 2)) > in.length)
        {
            throw new DataLengthException("input buffer too short");
        }

        if ((outOff + (32 / 2)) > out.length)
        {
            throw new DataLengthException("output buffer too short");
        }

        if (forEncryption)
        {
            unpackBlock(in, inOff);
            encryptBlock(WorkingKey);
            packBlock(out, outOff);
        }
        else
        {
            unpackBlock(in, inOff);
            decryptBlock(WorkingKey);
            packBlock(out, outOff);
        }

        return BLOCK_SIZE;
    }

    public void reset()
    {
    }

    private final void unpackBlock(
        byte[]      bytes,
        int         off)
    {
        int     index = off;

        C0 = (bytes[index++] & 0xff);
        C0 |= (bytes[index++] & 0xff) << 8;
        C0 |= (bytes[index++] & 0xff) << 16;
        C0 |= bytes[index++] << 24;

        C1 = (bytes[index++] & 0xff);
        C1 |= (bytes[index++] & 0xff) << 8;
        C1 |= (bytes[index++] & 0xff) << 16;
        C1 |= bytes[index++] << 24;

        C2 = (bytes[index++] & 0xff);
        C2 |= (bytes[index++] & 0xff) << 8;
        C2 |= (bytes[index++] & 0xff) << 16;
        C2 |= bytes[index++] << 24;

        C3 = (bytes[index++] & 0xff);
        C3 |= (bytes[index++] & 0xff) << 8;
        C3 |= (bytes[index++] & 0xff) << 16;
        C3 |= bytes[index++] << 24;
    }

    private final void packBlock(
        byte[]      bytes,
        int         off)
    {
        int     index = off;

        bytes[index++] = (byte)C0;
        bytes[index++] = (byte)(C0 >> 8);
        bytes[index++] = (byte)(C0 >> 16);
        bytes[index++] = (byte)(C0 >> 24);

        bytes[index++] = (byte)C1;
        bytes[index++] = (byte)(C1 >> 8);
        bytes[index++] = (byte)(C1 >> 16);
        bytes[index++] = (byte)(C1 >> 24);

        bytes[index++] = (byte)C2;
        bytes[index++] = (byte)(C2 >> 8);
        bytes[index++] = (byte)(C2 >> 16);
        bytes[index++] = (byte)(C2 >> 24);

        bytes[index++] = (byte)C3;
        bytes[index++] = (byte)(C3 >> 8);
        bytes[index++] = (byte)(C3 >> 16);
        bytes[index++] = (byte)(C3 >> 24);
    }

    private final void encryptBlock(int[][] KW)
    {
        int r, r0, r1, r2, r3;
        
        C0 ^= KW[0][0];
        C1 ^= KW[0][1];
        C2 ^= KW[0][2];
        C3 ^= KW[0][3];

        r = 1;
        while (r < ROUNDS - 1)
        {
            r0 = T0[C0&255] ^ T1[(C1>>8)&255] ^ T2[(C2>>16)&255] ^ T3[(C3>>24)&255] ^ KW[r][0];
            r1 = T0[C1&255] ^ T1[(C2>>8)&255] ^ T2[(C3>>16)&255] ^ T3[(C0>>24)&255] ^ KW[r][1];
            r2 = T0[C2&255] ^ T1[(C3>>8)&255] ^ T2[(C0>>16)&255] ^ T3[(C1>>24)&255] ^ KW[r][2];
            r3 = T0[C3&255] ^ T1[(C0>>8)&255] ^ T2[(C1>>16)&255] ^ T3[(C2>>24)&255] ^ KW[r++][3];
            C0 = T0[r0&255] ^ T1[(r1>>8)&255] ^ T2[(r2>>16)&255] ^ T3[(r3>>24)&255] ^ KW[r][0];
            C1 = T0[r1&255] ^ T1[(r2>>8)&255] ^ T2[(r3>>16)&255] ^ T3[(r0>>24)&255] ^ KW[r][1];
            C2 = T0[r2&255] ^ T1[(r3>>8)&255] ^ T2[(r0>>16)&255] ^ T3[(r1>>24)&255] ^ KW[r][2];
            C3 = T0[r3&255] ^ T1[(r0>>8)&255] ^ T2[(r1>>16)&255] ^ T3[(r2>>24)&255] ^ KW[r++][3];
        }

        r0 = T0[C0&255] ^ T1[(C1>>8)&255] ^ T2[(C2>>16)&255] ^ T3[(C3>>24)&255] ^ KW[r][0];
        r1 = T0[C1&255] ^ T1[(C2>>8)&255] ^ T2[(C3>>16)&255] ^ T3[(C0>>24)&255] ^ KW[r][1];
        r2 = T0[C2&255] ^ T1[(C3>>8)&255] ^ T2[(C0>>16)&255] ^ T3[(C1>>24)&255] ^ KW[r][2];
        r3 = T0[C3&255] ^ T1[(C0>>8)&255] ^ T2[(C1>>16)&255] ^ T3[(C2>>24)&255] ^ KW[r++][3];
        
        // the final round's table is a simple function of S so we don't use a whole other four tables for it

        C0 = (S[r0&255]&255) ^ ((S[(r1>>8)&255]&255)<<8) ^ ((S[(r2>>16)&255]&255)<<16) ^ (S[(r3>>24)&255]<<24) ^ KW[r][0];
        C1 = (S[r1&255]&255) ^ ((S[(r2>>8)&255]&255)<<8) ^ ((S[(r3>>16)&255]&255)<<16) ^ (S[(r0>>24)&255]<<24) ^ KW[r][1];
        C2 = (S[r2&255]&255) ^ ((S[(r3>>8)&255]&255)<<8) ^ ((S[(r0>>16)&255]&255)<<16) ^ (S[(r1>>24)&255]<<24) ^ KW[r][2];
        C3 = (S[r3&255]&255) ^ ((S[(r0>>8)&255]&255)<<8) ^ ((S[(r1>>16)&255]&255)<<16) ^ (S[(r2>>24)&255]<<24) ^ KW[r][3];

    }

    private final void decryptBlock(int[][] KW)
    {
        int r0, r1, r2, r3;

        C0 ^= KW[ROUNDS][0];
        C1 ^= KW[ROUNDS][1];
        C2 ^= KW[ROUNDS][2];
        C3 ^= KW[ROUNDS][3];

        int r = ROUNDS-1; 
        
        while (r>1) 
        {
            r0 = Tinv0[C0&255] ^ Tinv1[(C3>>8)&255] ^ Tinv2[(C2>>16)&255] ^ Tinv3[(C1>>24)&255] ^ KW[r][0];
            r1 = Tinv0[C1&255] ^ Tinv1[(C0>>8)&255] ^ Tinv2[(C3>>16)&255] ^ Tinv3[(C2>>24)&255] ^ KW[r][1];
            r2 = Tinv0[C2&255] ^ Tinv1[(C1>>8)&255] ^ Tinv2[(C0>>16)&255] ^ Tinv3[(C3>>24)&255] ^ KW[r][2];
            r3 = Tinv0[C3&255] ^ Tinv1[(C2>>8)&255] ^ Tinv2[(C1>>16)&255] ^ Tinv3[(C0>>24)&255] ^ KW[r--][3];
            C0 = Tinv0[r0&255] ^ Tinv1[(r3>>8)&255] ^ Tinv2[(r2>>16)&255] ^ Tinv3[(r1>>24)&255] ^ KW[r][0];
            C1 = Tinv0[r1&255] ^ Tinv1[(r0>>8)&255] ^ Tinv2[(r3>>16)&255] ^ Tinv3[(r2>>24)&255] ^ KW[r][1];
            C2 = Tinv0[r2&255] ^ Tinv1[(r1>>8)&255] ^ Tinv2[(r0>>16)&255] ^ Tinv3[(r3>>24)&255] ^ KW[r][2];
            C3 = Tinv0[r3&255] ^ Tinv1[(r2>>8)&255] ^ Tinv2[(r1>>16)&255] ^ Tinv3[(r0>>24)&255] ^ KW[r--][3];
        }

        r0 = Tinv0[C0&255] ^ Tinv1[(C3>>8)&255] ^ Tinv2[(C2>>16)&255] ^ Tinv3[(C1>>24)&255] ^ KW[r][0];
        r1 = Tinv0[C1&255] ^ Tinv1[(C0>>8)&255] ^ Tinv2[(C3>>16)&255] ^ Tinv3[(C2>>24)&255] ^ KW[r][1];
        r2 = Tinv0[C2&255] ^ Tinv1[(C1>>8)&255] ^ Tinv2[(C0>>16)&255] ^ Tinv3[(C3>>24)&255] ^ KW[r][2];
        r3 = Tinv0[C3&255] ^ Tinv1[(C2>>8)&255] ^ Tinv2[(C1>>16)&255] ^ Tinv3[(C0>>24)&255] ^ KW[r][3];
        
        // the final round's table is a simple function of Si so we don't use a whole other four tables for it

        C0 = (Si[r0&255]&255) ^ ((Si[(r3>>8)&255]&255)<<8) ^ ((Si[(r2>>16)&255]&255)<<16) ^ (Si[(r1>>24)&255]<<24) ^ KW[0][0];
        C1 = (Si[r1&255]&255) ^ ((Si[(r0>>8)&255]&255)<<8) ^ ((Si[(r3>>16)&255]&255)<<16) ^ (Si[(r2>>24)&255]<<24) ^ KW[0][1];
        C2 = (Si[r2&255]&255) ^ ((Si[(r1>>8)&255]&255)<<8) ^ ((Si[(r0>>16)&255]&255)<<16) ^ (Si[(r3>>24)&255]<<24) ^ KW[0][2];
        C3 = (Si[r3&255]&255) ^ ((Si[(r2>>8)&255]&255)<<8) ^ ((Si[(r1>>16)&255]&255)<<16) ^ (Si[(r0>>24)&255]<<24) ^ KW[0][3];
    }
}