aesengine.java~

KeePass for J2ME is a J2ME port of KeePass Password Safe, a free, open source, light-weight and easy

        int         KC = key.length / 4;  // key length in words
        int         t;
        
        if (((KC != 4) && (KC != 6) && (KC != 8)) || ((KC * 4) != key.length))
        {
            throw new IllegalArgumentException("Key length not 128/192/256 bits.");
        }

        ROUNDS = KC + 6;  // This is not always true for the generalized Rijndael that allows larger block sizes
        int[][] W = new int[ROUNDS+1][4];   // 4 words in a block
        
        //
        // copy the key into the round key array
        //
        
        t = 0;
        int i = 0;
        while (i < key.length)
            {
                W[t >> 2][t & 3] = (key[i]&0xff) | ((key[i+1]&0xff) << 8) | ((key[i+2]&0xff) << 16) | (key[i+3] << 24);
                i+=4;
                t++;
            }
        
        //
        // while not enough round key material calculated
        // calculate new values
        //
        int k = (ROUNDS + 1) << 2;
        for (i = KC; (i < k); i++)
            {
                int temp = W[(i-1)>>2][(i-1)&3];
                if ((i % KC) == 0)
                {
                    temp = subWord(shift(temp, 8)) ^ rcon[(i / KC)-1];
                }
                else if ((KC > 6) && ((i % KC) == 4))
                {
                    temp = subWord(temp);
                }
                
                W[i>>2][i&3] = W[(i - KC)>>2][(i-KC)&3] ^ temp;
            }

        if (!forEncryption)
        {
            for (int j = 1; j < ROUNDS; j++)
            {
                for (i = 0; i < 4; i++)
                {
                    W[j][i] = inv_mcol(W[j][i]);
                }
            }
        }

        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 AESEngine()
    {
    }

    /**
     * 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] ^ shift(T0[(C1>>8)&255], 24) ^ shift(T0[(C2>>16)&255],16) ^ shift(T0[(C3>>24)&255],8) ^ KW[r][0];
            r1 = T0[C1&255] ^ shift(T0[(C2>>8)&255], 24) ^ shift(T0[(C3>>16)&255], 16) ^ shift(T0[(C0>>24)&255], 8) ^ KW[r][1];
            r2 = T0[C2&255] ^ shift(T0[(C3>>8)&255], 24) ^ shift(T0[(C0>>16)&255], 16) ^ shift(T0[(C1>>24)&255], 8) ^ KW[r][2];
            r3 = T0[C3&255] ^ shift(T0[(C0>>8)&255], 24) ^ shift(T0[(C1>>16)&255], 16) ^ shift(T0[(C2>>24)&255], 8) ^ KW[r++][3];
            C0 = T0[r0&255] ^ shift(T0[(r1>>8)&255], 24) ^ shift(T0[(r2>>16)&255], 16) ^ shift(T0[(r3>>24)&255], 8) ^ KW[r][0];
            C1 = T0[r1&255] ^ shift(T0[(r2>>8)&255], 24) ^ shift(T0[(r3>>16)&255], 16) ^ shift(T0[(r0>>24)&255], 8) ^ KW[r][1];
            C2 = T0[r2&255] ^ shift(T0[(r3>>8)&255], 24) ^ shift(T0[(r0>>16)&255], 16) ^ shift(T0[(r1>>24)&255], 8) ^ KW[r][2];
            C3 = T0[r3&255] ^ shift(T0[(r0>>8)&255], 24) ^ shift(T0[(r1>>16)&255], 16) ^ shift(T0[(r2>>24)&255], 8) ^ KW[r++][3];
        }

        r0 = T0[C0&255] ^ shift(T0[(C1>>8)&255], 24) ^ shift(T0[(C2>>16)&255], 16) ^ shift(T0[(C3>>24)&255], 8) ^ KW[r][0];
        r1 = T0[C1&255] ^ shift(T0[(C2>>8)&255], 24) ^ shift(T0[(C3>>16)&255], 16) ^ shift(T0[(C0>>24)&255], 8) ^ KW[r][1];
        r2 = T0[C2&255] ^ shift(T0[(C3>>8)&255], 24) ^ shift(T0[(C0>>16)&255], 16) ^ shift(T0[(C1>>24)&255], 8) ^ KW[r][2];
        r3 = T0[C3&255] ^ shift(T0[(C0>>8)&255], 24) ^ shift(T0[(C1>>16)&255], 16) ^ shift(T0[(C2>>24)&255], 8) ^ 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 r, r0, r1, r2, r3;

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

        r = ROUNDS-1;

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

        r0 = Tinv0[C0&255] ^ shift(Tinv0[(C3>>8)&255], 24) ^ shift(Tinv0[(C2>>16)&255], 16) ^ shift(Tinv0[(C1>>24)&255], 8) ^ KW[r][0];
        r1 = Tinv0[C1&255] ^ shift(Tinv0[(C0>>8)&255], 24) ^ shift(Tinv0[(C3>>16)&255], 16) ^ shift(Tinv0[(C2>>24)&255], 8) ^ KW[r][1];
        r2 = Tinv0[C2&255] ^ shift(Tinv0[(C1>>8)&255], 24) ^ shift(Tinv0[(C0>>16)&255], 16) ^ shift(Tinv0[(C3>>24)&255], 8) ^ KW[r][2];
        r3 = Tinv0[C3&255] ^ shift(Tinv0[(C2>>8)&255], 24) ^ shift(Tinv0[(C1>>16)&255], 16) ^ shift(Tinv0[(C0>>24)&255], 8) ^ 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];
    }
}