// $Id: Rijndael_Algorithm.java,v 1.1 2001/05/21 02:24:30 jis Exp $
//
// $Log: Rijndael_Algorithm.java,v $
// Revision 1.1  2001/05/21 02:24:30  jis
// First version
//
// Revision 1.1  1998/04/12  Paulo
// + optimized methods for the default 128-bit block size.
//
// Revision 1.0  1998/03/11  Raif
// + original version.
//
// $Endlog$
/*
 * Copyright (c) 1997, 1998 Systemics Ltd on behalf of
 * the Cryptix Development Team. All rights reserved.
 */
package mit.Rijndael;

import java.io.PrintWriter;
import java.security.InvalidKeyException;

//...........................................................................
/**
 * Rijndael --pronounced Reindaal-- is a variable block-size (128-, 192- and
 * 256-bit), variable key-size (128-, 192- and 256-bit) symmetric cipher.<p>
 *
 * Rijndael was written by <a href="mailto:rijmen@esat.kuleuven.ac.be">Vincent
 * Rijmen</a> and <a href="mailto:Joan.Daemen@village.uunet.be">Joan Daemen</a>.<p>
 *
 * Portions of this code are <b>Copyright</b> &copy; 1997, 1998
 * <a href="http://www.systemics.com/">Systemics Ltd</a> on behalf of the
 * <a href="http://www.systemics.com/docs/cryptix/">Cryptix Development Team</a>.
 * <br>All rights reserved.<p>
 *
 * <b>$Revision: 1.1 $</b>
 * @author  Raif S. Naffah
 * @author  Paulo S. L. M. Barreto
 */
public final class Rijndael_Algorithm // implicit no-argument constructor
{
// Debugging methods and variables
//...........................................................................

    static final String NAME = "Rijndael_Algorithm";
    static final boolean IN = true, OUT = false;

    static final boolean DEBUG = Rijndael_Properties.GLOBAL_DEBUG;
    static final int debuglevel = DEBUG ? Rijndael_Properties.getLevel(NAME) : 0;
    static final PrintWriter err = DEBUG ? Rijndael_Properties.getOutput() : null;

    static final boolean TRACE = Rijndael_Properties.isTraceable(NAME);

    static void debug (String s) { err.println(">>> "+NAME+": "+s); }
    static void trace (boolean in, String s) {
        if (TRACE) err.println((in?"==> ":"<== ")+NAME+"."+s);
    }
    static void trace (String s) { if (TRACE) err.println("<=> "+NAME+"."+s); }


// Constants and variables
//...........................................................................

    static final int BLOCK_SIZE = 16; // default block size in bytes

    static final int[] alog = new int[256];
    static final int[] log =  new int[256];

    static final byte[] S =  new byte[256];
    static final byte[] Si = new byte[256];
    static final int[] T1 = new int[256];
    static final int[] T2 = new int[256];
    static final int[] T3 = new int[256];
    static final int[] T4 = new int[256];
    static final int[] T5 = new int[256];
    static final int[] T6 = new int[256];
    static final int[] T7 = new int[256];
    static final int[] T8 = new int[256];
    static final int[] U1 = new int[256];
    static final int[] U2 = new int[256];
    static final int[] U3 = new int[256];
    static final int[] U4 = new int[256];
    static final byte[] rcon = new byte[30];

    static final int[][][] shifts = new int[][][] {
        { {0, 0}, {1, 3}, {2, 2}, {3, 1} },
        { {0, 0}, {1, 5}, {2, 4}, {3, 3} },
        { {0, 0}, {1, 7}, {3, 5}, {4, 4} }
    };

    private static final char[] HEX_DIGITS = {
        '0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'
    };


// Static code - to intialise S-boxes and T-boxes
//...........................................................................

    static {
        long time = System.currentTimeMillis();

if (DEBUG && debuglevel > 6) {
System.out.println("Algorithm Name: "+Rijndael_Properties.FULL_NAME);
System.out.println("Electronic Codebook (ECB) Mode");
System.out.println();
}
        int ROOT = 0x11B;
        int i, j = 0;

        //
        // produce log and alog tables, needed for multiplying in the
        // field GF(2^m) (generator = 3)
        //
        alog[0] = 1;
        for (i = 1; i < 256; i++) {
            j = (alog[i-1] << 1) ^ alog[i-1];
            if ((j & 0x100) != 0) j ^= ROOT;
            alog[i] = j;
        }
        for (i = 1; i < 255; i++) log[alog[i]] = i;
        byte[][] A = new byte[][] {
            {1, 1, 1, 1, 1, 0, 0, 0},
            {0, 1, 1, 1, 1, 1, 0, 0},
		    {0, 0, 1, 1, 1, 1, 1, 0},
		    {0, 0, 0, 1, 1, 1, 1, 1},
		    {1, 0, 0, 0, 1, 1, 1, 1},
		    {1, 1, 0, 0, 0, 1, 1, 1},
		    {1, 1, 1, 0, 0, 0, 1, 1},
		    {1, 1, 1, 1, 0, 0, 0, 1}
		};
        byte[] B = new byte[] { 0, 1, 1, 0, 0, 0, 1, 1};

        //
        // substitution box based on F^{-1}(x)
        //
        int t;
        byte[][] box = new byte[256][8];
        box[1][7] = 1;
        for (i = 2; i < 256; i++) {
            j = alog[255 - log[i]];
            for (t = 0; t < 8; t++)
                box[i][t] = (byte)((j >>> (7 - t)) & 0x01);
        }
        //
        // affine transform:  box[i] <- B + A*box[i]
        //
        byte[][] cox = new byte[256][8];
        for (i = 0; i < 256; i++)
            for (t = 0; t < 8; t++) {
                cox[i][t] = B[t];
                for (j = 0; j < 8; j++)
                    cox[i][t] ^= A[t][j] * box[i][j];
            }
        //
        // S-boxes and inverse S-boxes
        //
        for (i = 0; i < 256; i++) {
            S[i] = (byte)(cox[i][0] << 7);
	        for (t = 1; t < 8; t++)
	            S[i] ^= cox[i][t] << (7-t);
            Si[S[i] & 0xFF] = (byte) i;
        }
        //
        // T-boxes
        //
        byte[][] G = new byte[][] {
            {2, 1, 1, 3},
            {3, 2, 1, 1},
            {1, 3, 2, 1},
            {1, 1, 3, 2}
        };
        byte[][] AA = new byte[4][8];
        for (i = 0; i < 4; i++) {
            for (j = 0; j < 4; j++) AA[i][j] = G[i][j];
            AA[i][i+4] = 1;
        }
        byte pivot, tmp;
        byte[][] iG = new byte[4][4];
        for (i = 0; i < 4; i++) {
            pivot = AA[i][i];
            if (pivot == 0) {
                t = i + 1;
                while ((AA[t][i] == 0) && (t < 4))
                    t++;
                if (t == 4)
                    throw new RuntimeException("G matrix is not invertible");
                else {
                    for (j = 0; j < 8; j++) {
                        tmp = AA[i][j];
                        AA[i][j] = AA[t][j];
                        AA[t][j] = (byte) tmp;
                    }
                    pivot = AA[i][i];
                }
            }
            for (j = 0; j < 8; j++)
                if (AA[i][j] != 0)
                    AA[i][j] = (byte)
                        alog[(255 + log[AA[i][j] & 0xFF] - log[pivot & 0xFF]) % 255];
            for (t = 0; t < 4; t++)
                if (i != t) {
                    for (j = i+1; j < 8; j++)
                        AA[t][j] ^= mul(AA[i][j], AA[t][i]);
                    AA[t][i] = 0;
                }
        }
        for (i = 0; i < 4; i++)
            for (j = 0; j < 4; j++) iG[i][j] = AA[i][j + 4];

        int s;
        for (t = 0; t < 256; t++) {
            s = S[t];
            T1[t] = mul4(s, G[0]);
            T2[t] = mul4(s, G[1]);
            T3[t] = mul4(s, G[2]);
            T4[t] = mul4(s, G[3]);

            s = Si[t];
            T5[t] = mul4(s, iG[0]);
            T6[t] = mul4(s, iG[1]);
            T7[t] = mul4(s, iG[2]);
            T8[t] = mul4(s, iG[3]);

            U1[t] = mul4(t, iG[0]);
            U2[t] = mul4(t, iG[1]);
            U3[t] = mul4(t, iG[2]);
            U4[t] = mul4(t, iG[3]);
        }
        //
        // round constants
        //
        rcon[0] = 1;
        int r = 1;
        for (t = 1; t < 30; ) rcon[t++] = (byte)(r = mul(2, r));

        time = System.currentTimeMillis() - time;

if (DEBUG && debuglevel > 8) {
System.out.println("==========");
System.out.println();
System.out.println("Static Data");
System.out.println();
System.out.println("S[]:"); for(i=0;i<16;i++) { for(j=0;j<16;j++) System.out.print("0x"+byteToString(S[i*16+j])+", "); System.out.println();}
System.out.println();
System.out.println("Si[]:"); for(i=0;i<16;i++) { for(j=0;j<16;j++) System.out.print("0x"+byteToString(Si[i*16+j])+", "); System.out.println();}

System.out.println();
System.out.println("iG[]:"); for(i=0;i<4;i++){for(j=0;j<4;j++) System.out.print("0x"+byteToString(iG[i][j])+", "); System.out.println();}

System.out.println();
System.out.println("T1[]:"); for(i=0;i<64;i++){for(j=0;j<4;j++) System.out.print("0x"+intToString(T1[i*4+j])+", "); System.out.println();}
System.out.println();
System.out.println("T2[]:"); for(i=0;i<64;i++){for(j=0;j<4;j++) System.out.print("0x"+intToString(T2[i*4+j])+", "); System.out.println();}
System.out.println();
System.out.println("T3[]:"); for(i=0;i<64;i++){for(j=0;j<4;j++) System.out.print("0x"+intToString(T3[i*4+j])+", "); System.out.println();}
System.out.println();
System.out.println("T4[]:"); for(i=0;i<64;i++){for(j=0;j<4;j++) System.out.print("0x"+intToString(T4[i*4+j])+", "); System.out.println();}
System.out.println();
System.out.println("T5[]:"); for(i=0;i<64;i++){for(j=0;j<4;j++) System.out.print("0x"+intToString(T5[i*4+j])+", "); System.out.println();}
System.out.println();
System.out.println("T6[]:"); for(i=0;i<64;i++){for(j=0;j<4;j++) System.out.print("0x"+intToString(T6[i*4+j])+", "); System.out.println();}
System.out.println();
System.out.println("T7[]:"); for(i=0;i<64;i++){for(j=0;j<4;j++) System.out.print("0x"+intToString(T7[i*4+j])+", "); System.out.println();}
System.out.println();
System.out.println("T8[]:"); for(i=0;i<64;i++){for(j=0;j<4;j++) System.out.print("0x"+intToString(T8[i*4+j])+", "); System.out.println();}

System.out.println();
System.out.println("U1[]:"); for(i=0;i<64;i++){for(j=0;j<4;j++) System.out.print("0x"+intToString(U1[i*4+j])+", "); System.out.println();}
System.out.println();
System.out.println("U2[]:"); for(i=0;i<64;i++){for(j=0;j<4;j++) System.out.print("0x"+intToString(U2[i*4+j])+", "); System.out.println();}
System.out.println();
System.out.println("U3[]:"); for(i=0;i<64;i++){for(j=0;j<4;j++) System.out.print("0x"+intToString(U3[i*4+j])+", "); System.out.println();}
System.out.println();
System.out.println("U4[]:"); for(i=0;i<64;i++){for(j=0;j<4;j++) System.out.print("0x"+intToString(U4[i*4+j])+", "); System.out.println();}

System.out.println();
System.out.println("rcon[]:"); for(i=0;i<5;i++){for(j=0;j<6;j++) System.out.print("0x"+byteToString(rcon[i*6+j])+", "); System.out.println();}

System.out.println();
System.out.println("Total initialization time: "+time+" ms.");
System.out.println();
}
    }

    // multiply two elements of GF(2^m)
    static final int mul (int a, int b) {
        return (a != 0 && b != 0) ?
            alog[(log[a & 0xFF] + log[b & 0xFF]) % 255] :
            0;
    }

    // convenience method used in generating Transposition boxes
    static final int mul4 (int a, byte[] b) {
        if (a == 0) return 0;
        a = log[a & 0xFF];
        int a0 = (b[0] != 0) ? alog[(a + log[b[0] & 0xFF]) % 255] & 0xFF : 0;
        int a1 = (b[1] != 0) ? alog[(a + log[b[1] & 0xFF]) % 255] & 0xFF : 0;
        int a2 = (b[2] != 0) ? alog[(a + log[b[2] & 0xFF]) % 255] & 0xFF : 0;
        int a3 = (b[3] != 0) ? alog[(a + log[b[3] & 0xFF]) % 255] & 0xFF : 0;
        return a0 << 24 | a1 << 16 | a2 << 8 | a3;
    }


// Basic API methods
//...........................................................................

    /**
     * Convenience method to expand a user-supplied key material into a
     * session key, assuming Rijndael's default block size (128-bit).
     *
     * @param key The 128/192/256-bit user-key to use.
     * @exception  InvalidKeyException  If the key is invalid.
     */
    public static Object makeKey (byte[] k) throws InvalidKeyException {
        return makeKey(k, BLOCK_SIZE);
    }

    /**
     * Convenience method to encrypt exactly one block of plaintext, assuming
     * Rijndael's default block size (128-bit).
     *
     * @param  in         The plaintext.
     * @param  inOffset   Index of in from which to start considering data.
     * @param  sessionKey The session key to use for encryption.
     * @return The ciphertext generated from a plaintext using the session key.
     */
    public static byte[]
    blockEncrypt (byte[] in, int inOffset, Object sessionKey) {
if (DEBUG) trace(IN, "blockEncrypt("+in+", "+inOffset+", "+sessionKey+")");
        int[][] Ke = (int[][]) ((Object[]) sessionKey)[0]; // extract encryption round keys
        int ROUNDS = Ke.length - 1;
        int[] Ker = Ke[0];

        // plaintext to ints + key
        int t0   = ((in[inOffset++] & 0xFF) << 24 |
                    (in[inOffset++] & 0xFF) << 16 |
                    (in[inOffset++] & 0xFF) <<  8 |
                    (in[inOffset++] & 0xFF)        ) ^ Ker[0];
        int t1   = ((in[inOffset++] & 0xFF) << 24 |
                    (in[inOffset++] & 0xFF) << 16 |
                    (in[inOffset++] & 0xFF) <<  8 |
                    (in[inOffset++] & 0xFF)        ) ^ Ker[1];
        int t2   = ((in[inOffset++] & 0xFF) << 24 |
                    (in[inOffset++] & 0xFF) << 16 |
                    (in[inOffset++] & 0xFF) <<  8 |
                    (in[inOffset++] & 0xFF)        ) ^ Ker[2];
        int t3   = ((in[inOffset++] & 0xFF) << 24 |
                    (in[inOffset++] & 0xFF) << 16 |
                    (in[inOffset++] & 0xFF) <<  8 |
                    (in[inOffset++] & 0xFF)        ) ^ Ker[3];

        int a0, a1, a2, a3;
        for (int r = 1; r < ROUNDS; r++) {          // apply round transforms
            Ker = Ke[r];
            a0   = (T1[(t0 >>> 24) & 0xFF] ^
                    T2[(t1 >>> 16) & 0xFF] ^
                    T3[(t2 >>>  8) & 0xFF] ^
                    T4[ t3         & 0xFF]  ) ^ Ker[0];
            a1   = (T1[(t1 >>> 24) & 0xFF] ^
                    T2[(t2 >>> 16) & 0xFF] ^
                    T3[(t3 >>>  8) & 0xFF] ^
                    T4[ t0         & 0xFF]  ) ^ Ker[1];
            a2   = (T1[(t2 >>> 24) & 0xFF] ^
                    T2[(t3 >>> 16) & 0xFF] ^
                    T3[(t0 >>>  8) & 0xFF] ^
                    T4[ t1         & 0xFF]  ) ^ Ker[2];
            a3   = (T1[(t3 >>> 24) & 0xFF] ^
                    T2[(t0 >>> 16) & 0xFF] ^
                    T3[(t1 >>>  8) & 0xFF] ^
                    T4[ t2         & 0xFF]  ) ^ Ker[3];
            t0 = a0;
            t1 = a1;
            t2 = a2;
            t3 = a3;
if (DEBUG && debuglevel > 6) System.out.println("CT"+r+"="+intToString(t0)+intToString(t1)+intToString(t2)+intToString(t3));
        }

        // last round is special
        byte[] result = new byte[BLOCK_SIZE]; // the resulting ciphertext
        Ker = Ke[ROUNDS];
        int tt = Ker[0];
        result[ 0] = (byte)(S[(t0 >>> 24) & 0xFF] ^ (tt >>> 24));
        result[ 1] = (byte)(S[(t1 >>> 16) & 0xFF] ^ (tt >>> 16));
        result[ 2] = (byte)(S[(t2 >>>  8) & 0xFF] ^ (tt >>>  8));
        result[ 3] = (byte)(S[ t3         & 0xFF] ^  tt        );
        tt = Ker[1];
        result[ 4] = (byte)(S[(t1 >>> 24) & 0xFF] ^ (tt >>> 24));
        result[ 5] = (byte)(S[(t2 >>> 16) & 0xFF] ^ (tt >>> 16));
        result[ 6] = (byte)(S[(t3 >>>  8) & 0xFF] ^ (tt >>>  8));
        result[ 7] = (byte)(S[ t0         & 0xFF] ^  tt        );
        tt = Ker[2];
        result[ 8] = (byte)(S[(t2 >>> 24) & 0xFF] ^ (tt >>> 24));
        result[ 9] = (byte)(S[(t3 >>> 16) & 0xFF] ^ (tt >>> 16));
        result[10] = (byte)(S[(t0 >>>  8) & 0xFF] ^ (tt >>>  8));
        result[11] = (byte)(S[ t1         & 0xFF] ^  tt        );
        tt = Ker[3];
        result[12] = (byte)(S[(t3 >>> 24) & 0xFF] ^ (tt >>> 24));
        result[13] = (byte)(S[(t0 >>> 16) & 0xFF] ^ (tt >>> 16));
        result[14] = (byte)(S[(t1 >>>  8) & 0xFF] ^ (tt >>>  8));
        result[15] = (byte)(S[ t2         & 0xFF] ^  tt        );
if (DEBUG && debuglevel > 6) {
System.out.println("CT="+toString(result));
System.out.println();
}
if (DEBUG) trace(OUT, "blockEncrypt()");
        return result;
    }

    /**
     * Convenience method to decrypt exactly one block of plaintext, assuming
     * Rijndael's default block size (128-bit).
     *
     * @param  in         The ciphertext.
     * @param  inOffset   Index of in from which to start considering data.
     * @param  sessionKey The session key to use for decryption.
     * @return The plaintext generated from a ciphertext using the session key.
     */
    public static byte[]
    blockDecrypt (byte[] in, int inOffset, Object sessionKey) {
if (DEBUG) trace(IN, "blockDecrypt("+in+", "+inOffset+", "+sessionKey+")");
        int[][] Kd = (int[][]) ((Object[]) sessionKey)[1]; // extract decryption round keys
        int ROUNDS = Kd.length - 1;
        int[] Kdr = Kd[0];

        // ciphertext to ints + key
        int t0   = ((in[inOffset++] & 0xFF) << 24 |
                    (in[inOffset++] & 0xFF) << 16 |
                    (in[inOffset++] & 0xFF) <<  8 |
                    (in[inOffset++] & 0xFF)        ) ^ Kdr[0];
        int t1   = ((in[inOffset++] & 0xFF) << 24 |
                    (in[inOffset++] & 0xFF) << 16 |
                    (in[inOffset++] & 0xFF) <<  8 |
                    (in[inOffset++] & 0xFF)        ) ^ Kdr[1];
        int t2   = ((in[inOffset++] & 0xFF) << 24 |
                    (in[inOffset++] & 0xFF) << 16 |
                    (in[inOffset++] & 0xFF) <<  8 |
                    (in[inOffset++] & 0xFF)        ) ^ Kdr[2];
        int t3   = ((in[inOffset++] & 0xFF) << 24 |
                    (in[inOffset++] & 0xFF) << 16 |
                    (in[inOffset++] & 0xFF) <<  8 |
                    (in[inOffset++] & 0xFF)        ) ^ Kdr[3];

        int a0, a1, a2, a3;
        for (int r = 1; r < ROUNDS; r++) {          // apply round transforms
            Kdr = Kd[r];
            a0   = (T5[(t0 >>> 24) & 0xFF] ^
                    T6[(t3 >>> 16) & 0xFF] ^
                    T7[(t2 >>>  8) & 0xFF] ^
                    T8[ t1         & 0xFF]  ) ^ Kdr[0];
            a1   = (T5[(t1 >>> 24) & 0xFF] ^
                    T6[(t0 >>> 16) & 0xFF] ^
                    T7[(t3 >>>  8) & 0xFF] ^
                    T8[ t2         & 0xFF]  ) ^ Kdr[1];
            a2   = (T5[(t2 >>> 24) & 0xFF] ^
                    T6[(t1 >>> 16) & 0xFF] ^
                    T7[(t0 >>>  8) & 0xFF] ^
                    T8[ t3         & 0xFF]  ) ^ Kdr[2];
            a3   = (T5[(t3 >>> 24) & 0xFF] ^
                    T6[(t2 >>> 16) & 0xFF] ^
                    T7[(t1 >>>  8) & 0xFF] ^
                    T8[ t0         & 0xFF]  ) ^ Kdr[3];
            t0 = a0;
            t1 = a1;
            t2 = a2;
            t3 = a3;
if (DEBUG && debuglevel > 6) System.out.println("PT"+r+"="+intToString(t0)+intToString(t1)+intToString(t2)+intToString(t3));
        }

        // last round is special
        byte[] result = new byte[16]; // the resulting plaintext
        Kdr = Kd[ROUNDS];
        int tt = Kdr[0];
        result[ 0] = (byte)(Si[(t0 >>> 24) & 0xFF] ^ (tt >>> 24));
        result[ 1] = (byte)(Si[(t3 >>> 16) & 0xFF] ^ (tt >>> 16));
        result[ 2] = (byte)(Si[(t2 >>>  8) & 0xFF] ^ (tt >>>  8));
        result[ 3] = (byte)(Si[ t1         & 0xFF] ^  tt        );
        tt = Kdr[1];
        result[ 4] = (byte)(Si[(t1 >>> 24) & 0xFF] ^ (tt >>> 24));
        result[ 5] = (byte)(Si[(t0 >>> 16) & 0xFF] ^ (tt >>> 16));
        result[ 6] = (byte)(Si[(t3 >>>  8) & 0xFF] ^ (tt >>>  8));
        result[ 7] = (byte)(Si[ t2         & 0xFF] ^  tt        );
        tt = Kdr[2];
        result[ 8] = (byte)(Si[(t2 >>> 24) & 0xFF] ^ (tt >>> 24));
        result[ 9] = (byte)(Si[(t1 >>> 16) & 0xFF] ^ (tt >>> 16));
        result[10] = (byte)(Si[(t0 >>>  8) & 0xFF] ^ (tt >>>  8));
        result[11] = (byte)(Si[ t3         & 0xFF] ^  tt        );
        tt = Kdr[3];
        result[12] = (byte)(Si[(t3 >>> 24) & 0xFF] ^ (tt >>> 24));
        result[13] = (byte)(Si[(t2 >>> 16) & 0xFF] ^ (tt >>> 16));
        result[14] = (byte)(Si[(t1 >>>  8) & 0xFF] ^ (tt >>>  8));
        result[15] = (byte)(Si[ t0         & 0xFF] ^  tt        );
if (DEBUG && debuglevel > 6) {
System.out.println("PT="+toString(result));
System.out.println();
}
if (DEBUG) trace(OUT, "blockDecrypt()");
        return result;
    }

    /** A basic symmetric encryption/decryption test. */
    public static boolean self_test() { return self_test(BLOCK_SIZE); }


// Rijndael own methods
//...........................................................................

    /** @return The default length in bytes of the Algorithm input block. */
    public static int blockSize() { return BLOCK_SIZE; }

    /**
     * Expand a user-supplied key material into a session key.
     *
     * @param key        The 128/192/256-bit user-key to use.
     * @param blockSize  The block size in bytes of this Rijndael.
     * @exception  InvalidKeyException  If the key is invalid.
     */
    public static synchronized Object makeKey (byte[] k, int blockSize)
    throws InvalidKeyException {
if (DEBUG) trace(IN, "makeKey("+k+", "+blockSize+")");
        if (k == null)
            throw new InvalidKeyException("Empty key");
        if (!(k.length == 16 || k.length == 24 || k.length == 32))
             throw new InvalidKeyException("Incorrect key length");
        int ROUNDS = getRounds(k.length, blockSize);
        int BC = blockSize / 4;
        int[][] Ke = new int[ROUNDS + 1][BC]; // encryption round keys
        int[][] Kd = new int[ROUNDS + 1][BC]; // decryption round keys
        int ROUND_KEY_COUNT = (ROUNDS + 1) * BC;
        int KC = k.length / 4;
        int[] tk = new int[KC];
        int i, j;

        // copy user material bytes into temporary ints
        for (i = 0, j = 0; i < KC; )
            tk[i++] = (k[j++] & 0xFF) << 24 |
                      (k[j++] & 0xFF) << 16 |
                      (k[j++] & 0xFF) <<  8 |
                      (k[j++] & 0xFF);
        // copy values into round key arrays
        int t = 0;
        for (j = 0; (j < KC) && (t < ROUND_KEY_COUNT); j++, t++) {
            Ke[t / BC][t % BC] = tk[j];
            Kd[ROUNDS - (t / BC)][t % BC] = tk[j];
        }
        int tt, rconpointer = 0;
        while (t < ROUND_KEY_COUNT) {
            // extrapolate using phi (the round key evolution function)
            tt = tk[KC - 1];
            tk[0] ^= (S[(tt >>> 16) & 0xFF] & 0xFF) << 24 ^
                     (S[(tt >>>  8) & 0xFF] & 0xFF) << 16 ^
                     (S[ tt         & 0xFF] & 0xFF) <<  8 ^
                     (S[(tt >>> 24) & 0xFF] & 0xFF)       ^
                     (rcon[rconpointer++]   & 0xFF) << 24;
            if (KC != 8)
                for (i = 1, j = 0; i < KC; ) tk[i++] ^= tk[j++];
            else {
                for (i = 1, j = 0; i < KC / 2; ) tk[i++] ^= tk[j++];
                tt = tk[KC / 2 - 1];
                tk[KC / 2] ^= (S[ tt         & 0xFF] & 0xFF)       ^
                              (S[(tt >>>  8) & 0xFF] & 0xFF) <<  8 ^
                              (S[(tt >>> 16) & 0xFF] & 0xFF) << 16 ^
                              (S[(tt >>> 24) & 0xFF] & 0xFF) << 24;
                for (j = KC / 2, i = j + 1; i < KC; ) tk[i++] ^= tk[j++];
            }
            // copy values into round key arrays
            for (j = 0; (j < KC) && (t < ROUND_KEY_COUNT); j++, t++) {
                Ke[t / BC][t % BC] = tk[j];
                Kd[ROUNDS - (t / BC)][t % BC] = tk[j];
            }
        }
        for (int r = 1; r < ROUNDS; r++)    // inverse MixColumn where needed
            for (j = 0; j < BC; j++) {
                tt = Kd[r][j];
                Kd[r][j] = U1[(tt >>> 24) & 0xFF] ^
                           U2[(tt >>> 16) & 0xFF] ^
                           U3[(tt >>>  8) & 0xFF] ^
                           U4[ tt         & 0xFF];
            }
        // assemble the encryption (Ke) and decryption (Kd) round keys into
        // one sessionKey object
        Object[] sessionKey = new Object[] {Ke, Kd};
if (DEBUG) trace(OUT, "makeKey()");
        return sessionKey;
    }

    /**
     * Encrypt exactly one block of plaintext.
     *
     * @param  in         The plaintext.
     * @param  inOffset   Index of in from which to start considering data.
     * @param  sessionKey The session key to use for encryption.
     * @param  blockSize  The block size in bytes of this Rijndael.
     * @return The ciphertext generated from a plaintext using the session key.
     */
    public static byte[]
    blockEncrypt (byte[] in, int inOffset, Object sessionKey, int blockSize) {
        if (blockSize == BLOCK_SIZE)
            return blockEncrypt(in, inOffset, sessionKey);
if (DEBUG) trace(IN, "blockEncrypt("+in+", "+inOffset+", "+sessionKey+", "+blockSize+")");
        Object[] sKey = (Object[]) sessionKey; // extract encryption round keys
        int[][] Ke = (int[][]) sKey[0];

        int BC = blockSize / 4;
        int ROUNDS = Ke.length - 1;
        int SC = BC == 4 ? 0 : (BC == 6 ? 1 : 2);
        int s1 = shifts[SC][1][0];
        int s2 = shifts[SC][2][0];
        int s3 = shifts[SC][3][0];
        int[] a = new int[BC];
        int[] t = new int[BC]; // temporary work array
        int i;
        byte[] result = new byte[blockSize]; // the resulting ciphertext
        int j = 0, tt;

        for (i = 0; i < BC; i++)                   // plaintext to ints + key
            t[i] = ((in[inOffset++] & 0xFF) << 24 |
                    (in[inOffset++] & 0xFF) << 16 |
                    (in[inOffset++] & 0xFF) <<  8 |
                    (in[inOffset++] & 0xFF)        ) ^ Ke[0][i];
        for (int r = 1; r < ROUNDS; r++) {          // apply round transforms
            for (i = 0; i < BC; i++)
                a[i] = (T1[(t[ i           ] >>> 24) & 0xFF] ^
                        T2[(t[(i + s1) % BC] >>> 16) & 0xFF] ^
                        T3[(t[(i + s2) % BC] >>>  8) & 0xFF] ^
                        T4[ t[(i + s3) % BC]         & 0xFF]  ) ^ Ke[r][i];
            System.arraycopy(a, 0, t, 0, BC);
if (DEBUG && debuglevel > 6) System.out.println("CT"+r+"="+toString(t));
        }
        for (i = 0; i < BC; i++) {                   // last round is special
            tt = Ke[ROUNDS][i];
            result[j++] = (byte)(S[(t[ i           ] >>> 24) & 0xFF] ^ (tt >>> 24));
            result[j++] = (byte)(S[(t[(i + s1) % BC] >>> 16) & 0xFF] ^ (tt >>> 16));
            result[j++] = (byte)(S[(t[(i + s2) % BC] >>>  8) & 0xFF] ^ (tt >>>  8));
            result[j++] = (byte)(S[ t[(i + s3) % BC]         & 0xFF] ^ tt);
        }
if (DEBUG && debuglevel > 6) {
System.out.println("CT="+toString(result));
System.out.println();
}
if (DEBUG) trace(OUT, "blockEncrypt()");
        return result;
    }

    /**
     * Decrypt exactly one block of ciphertext.
     *
     * @param  in         The ciphertext.
     * @param  inOffset   Index of in from which to start considering data.
     * @param  sessionKey The session key to use for decryption.
     * @param  blockSize  The block size in bytes of this Rijndael.
     * @return The plaintext generated from a ciphertext using the session key.
     */
    public static byte[]
    blockDecrypt (byte[] in, int inOffset, Object sessionKey, int blockSize) {
        if (blockSize == BLOCK_SIZE)
            return blockDecrypt(in, inOffset, sessionKey);
if (DEBUG) trace(IN, "blockDecrypt("+in+", "+inOffset+", "+sessionKey+", "+blockSize+")");
        Object[] sKey = (Object[]) sessionKey; // extract decryption round keys
        int[][] Kd = (int[][]) sKey[1];

        int BC = blockSize / 4;
        int ROUNDS = Kd.length - 1;
        int SC = BC == 4 ? 0 : (BC == 6 ? 1 : 2);
        int s1 = shifts[SC][1][1];
        int s2 = shifts[SC][2][1];
        int s3 = shifts[SC][3][1];
        int[] a = new int[BC];
        int[] t = new int[BC]; // temporary work array
        int i;
        byte[] result = new byte[blockSize]; // the resulting plaintext
        int j = 0, tt;

        for (i = 0; i < BC; i++)                   // ciphertext to ints + key
            t[i] = ((in[inOffset++] & 0xFF) << 24 |
                    (in[inOffset++] & 0xFF) << 16 |
                    (in[inOffset++] & 0xFF) <<  8 |
                    (in[inOffset++] & 0xFF)        ) ^ Kd[0][i];
        for (int r = 1; r < ROUNDS; r++) {          // apply round transforms
            for (i = 0; i < BC; i++)
                a[i] = (T5[(t[ i           ] >>> 24) & 0xFF] ^
                        T6[(t[(i + s1) % BC] >>> 16) & 0xFF] ^
                        T7[(t[(i + s2) % BC] >>>  8) & 0xFF] ^
                        T8[ t[(i + s3) % BC]         & 0xFF]  ) ^ Kd[r][i];
            System.arraycopy(a, 0, t, 0, BC);
if (DEBUG && debuglevel > 6) System.out.println("PT"+r+"="+toString(t));
        }
        for (i = 0; i < BC; i++) {                   // last round is special
            tt = Kd[ROUNDS][i];
            result[j++] = (byte)(Si[(t[ i           ] >>> 24) & 0xFF] ^ (tt >>> 24));
            result[j++] = (byte)(Si[(t[(i + s1) % BC] >>> 16) & 0xFF] ^ (tt >>> 16));
            result[j++] = (byte)(Si[(t[(i + s2) % BC] >>>  8) & 0xFF] ^ (tt >>>  8));
            result[j++] = (byte)(Si[ t[(i + s3) % BC]         & 0xFF] ^ tt);
        }
if (DEBUG && debuglevel > 6) {
System.out.println("PT="+toString(result));
System.out.println();
}
if (DEBUG) trace(OUT, "blockDecrypt()");
        return result;
    }

    /** A basic symmetric encryption/decryption test for a given key size. */
    private static boolean self_test (int keysize) {
if (DEBUG) trace(IN, "self_test("+keysize+")");
        boolean ok = false;
        try {
            byte[] kb = new byte[keysize];
            byte[] pt = new byte[BLOCK_SIZE];
            int i;

            for (i = 0; i < keysize; i++)
                kb[i] = (byte) i;
            for (i = 0; i < BLOCK_SIZE; i++)
                pt[i] = (byte) i;

if (DEBUG && debuglevel > 6) {
System.out.println("==========");
System.out.println();
System.out.println("KEYSIZE="+(8*keysize));
System.out.println("KEY="+toString(kb));
System.out.println();
}
            Object key = makeKey(kb, BLOCK_SIZE);

if (DEBUG && debuglevel > 6) {
System.out.println("Intermediate Ciphertext Values (Encryption)");
System.out.println();
System.out.println("PT="+toString(pt));
}
            byte[] ct =  blockEncrypt(pt, 0, key, BLOCK_SIZE);

if (DEBUG && debuglevel > 6) {
System.out.println("Intermediate Plaintext Values (Decryption)");
System.out.println();
System.out.println("CT="+toString(ct));
}
            byte[] cpt = blockDecrypt(ct, 0, key, BLOCK_SIZE);

            ok = areEqual(pt, cpt);
            if (!ok)
                throw new RuntimeException("Symmetric operation failed");
        }
        catch (Exception x) {
if (DEBUG && debuglevel > 0) {
    debug("Exception encountered during self-test: " + x.getMessage());
    x.printStackTrace();
}
        }
if (DEBUG && debuglevel > 0) debug("Self-test OK? " + ok);
if (DEBUG) trace(OUT, "self_test()");
        return ok;
    }

    /**
     * Return The number of rounds for a given Rijndael's key and block sizes.
     *
     * @param keySize    The size of the user key material in bytes.
     * @param blockSize  The desired block size in bytes.
     * @return The number of rounds for a given Rijndael's key and
     *      block sizes.
     */
    public static int getRounds (int keySize, int blockSize) {
        switch (keySize) {
        case 16:
            return blockSize == 16 ? 10 : (blockSize == 24 ? 12 : 14);
        case 24:
            return blockSize != 32 ? 12 : 14;
        default: // 32 bytes = 256 bits
            return 14;
        }
    }


// utility static methods (from cryptix.util.core ArrayUtil and Hex classes)
//...........................................................................

    /**
     * Compares two byte arrays for equality.
     *
     * @return true if the arrays have identical contents
     */
    private static boolean areEqual (byte[] a, byte[] b) {
        int aLength = a.length;
        if (aLength != b.length)
            return false;
        for (int i = 0; i < aLength; i++)
            if (a[i] != b[i])
                return false;
        return true;
    }

    /**
     * Returns a string of 2 hexadecimal digits (most significant
     * digit first) corresponding to the lowest 8 bits of <i>n</i>.
     */
    private static String byteToString (int n) {
        char[] buf = {
            HEX_DIGITS[(n >>> 4) & 0x0F],
            HEX_DIGITS[ n        & 0x0F]
        };
        return new String(buf);
    }

    /**
     * Returns a string of 8 hexadecimal digits (most significant
     * digit first) corresponding to the integer <i>n</i>, which is
     * treated as unsigned.
     */
    private static String intToString (int n) {
        char[] buf = new char[8];
        for (int i = 7; i >= 0; i--) {
            buf[i] = HEX_DIGITS[n & 0x0F];
            n >>>= 4;
        }
        return new String(buf);
    }

    /**
     * Returns a string of hexadecimal digits from a byte array. Each
     * byte is converted to 2 hex symbols.
     */
    private static String toString (byte[] ba) {
        int length = ba.length;
        char[] buf = new char[length * 2];
        for (int i = 0, j = 0, k; i < length; ) {
            k = ba[i++];
            buf[j++] = HEX_DIGITS[(k >>> 4) & 0x0F];
            buf[j++] = HEX_DIGITS[ k        & 0x0F];
        }
        return new String(buf);
    }

    /**
     * Returns a string of hexadecimal digits from an integer array. Each
     * int is converted to 4 hex symbols.
     */
    private static String toString (int[] ia) {
        int length = ia.length;
        char[] buf = new char[length * 8];
        for (int i = 0, j = 0, k; i < length; i++) {
            k = ia[i];
            buf[j++] = HEX_DIGITS[(k >>> 28) & 0x0F];
            buf[j++] = HEX_DIGITS[(k >>> 24) & 0x0F];
            buf[j++] = HEX_DIGITS[(k >>> 20) & 0x0F];
            buf[j++] = HEX_DIGITS[(k >>> 16) & 0x0F];
            buf[j++] = HEX_DIGITS[(k >>> 12) & 0x0F];
            buf[j++] = HEX_DIGITS[(k >>>  8) & 0x0F];
            buf[j++] = HEX_DIGITS[(k >>>  4) & 0x0F];
            buf[j++] = HEX_DIGITS[ k         & 0x0F];
        }
        return new String(buf);
    }


// main(): use to generate the Intermediate Values KAT
//...........................................................................

    public static void main (String[] args) {
        self_test(16);
        self_test(24);
        self_test(32);
    }
}