/*
* Copyright 2010 Srikanth Reddy Lingala  
* 
* Licensed under the Apache License, Version 2.0 (the "License"); 
* you may not use this file except in compliance with the License. 
* You may obtain a copy of the License at 
* 
* http://www.apache.org/licenses/LICENSE-2.0 
* 
* Unless required by applicable law or agreed to in writing, 
* software distributed under the License is distributed on an "AS IS" BASIS, 
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
* See the License for the specific language governing permissions and 
* limitations under the License. 
*/

package net.lingala.zip4j.crypto.engine;

import net.lingala.zip4j.exception.ZipException;
import net.lingala.zip4j.util.InternalZipConstants;

/**
 * Core Engine for AES Encryption
 * @author Srikanth Reddy Lingala
 *
 */
public class AESEngine {
	
	private int rounds;
    private int[][] workingKey = null;
    private int C0, C1, C2, C3;
	
    public AESEngine(byte[] key) throws ZipException {
		init(key);
	}
    
    public void init(byte[] key) throws ZipException {
        workingKey = generateWorkingKey(key);
    }
    
    private int[][] generateWorkingKey(byte[] key) throws ZipException {
        int         kc = key.length / 4;
        int         t;
        
        if (((kc != 4) && (kc != 6) && (kc != 8)) || ((kc * 4) != key.length))
        {
            throw new ZipException("invalid key length (not 128/192/256)");
        }

        rounds = kc + 6;
        int[][] W = new int[rounds+1][4];
        
        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++;
        }
        
        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;
        }
        return W;
    }
    
    public int processBlock(byte[] in, byte[] out) throws ZipException {
    	return processBlock(in, 0, out, 0);
    }
    
    public int processBlock(byte[] in, int inOff, byte[] out, int outOff) throws ZipException {
        if (workingKey == null)
        {
            throw new ZipException("AES engine not initialised");
        }

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

        if ((outOff + (32 / 2)) > out.length)
        {
            throw new ZipException("output buffer too short");
        }
        
        stateIn(in, inOff);
        encryptBlock(workingKey);
        stateOut(out, outOff);
        
        return InternalZipConstants.AES_BLOCK_SIZE;
    }

    private final void stateIn(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 stateOut(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];

        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 int shift(int r, int shift) {
        return (r >>> shift) | (r << -shift);
    }
    
    private int subWord(int x) {
        return (S[x&255]&255 | ((S[(x>>8)&255]&255)<<8) | ((S[(x>>16)&255]&255)<<16) | S[(x>>24)&255]<<24);
    }
    
    private static final byte[] S = {
        (byte)99, (byte)124, (byte)119, (byte)123, (byte)242, (byte)107, (byte)111, (byte)197,
        (byte)48,   (byte)1, (byte)103,  (byte)43, (byte)254, (byte)215, (byte)171, (byte)118,
        (byte)202, (byte)130, (byte)201, (byte)125, (byte)250,  (byte)89,  (byte)71, (byte)240,
        (byte)173, (byte)212, (byte)162, (byte)175, (byte)156, (byte)164, (byte)114, (byte)192,
        (byte)183, (byte)253, (byte)147,  (byte)38,  (byte)54,  (byte)63, (byte)247, (byte)204,
        (byte)52, (byte)165, (byte)229, (byte)241, (byte)113, (byte)216,  (byte)49,  (byte)21,
        (byte)4, (byte)199,  (byte)35, (byte)195,  (byte)24, (byte)150,   (byte)5, (byte)154,
        (byte)7,  (byte)18, (byte)128, (byte)226, (byte)235,  (byte)39, (byte)178, (byte)117,
        (byte)9, (byte)131,  (byte)44,  (byte)26,  (byte)27, (byte)110,  (byte)90, (byte)160,
        (byte)82,  (byte)59, (byte)214, (byte)179,  (byte)41, (byte)227,  (byte)47, (byte)132,
        (byte)83, (byte)209,   (byte)0, (byte)237,  (byte)32, (byte)252, (byte)177,  (byte)91,
        (byte)106, (byte)203, (byte)190,  (byte)57,  (byte)74,  (byte)76,  (byte)88, (byte)207,
        (byte)208, (byte)239, (byte)170, (byte)251,  (byte)67,  (byte)77,  (byte)51, (byte)133,
        (byte)69, (byte)249,   (byte)2, (byte)127,  (byte)80,  (byte)60, (byte)159, (byte)168,
        (byte)81, (byte)163,  (byte)64, (byte)143, (byte)146, (byte)157,  (byte)56, (byte)245,
        (byte)188, (byte)182, (byte)218,  (byte)33,  (byte)16, (byte)255, (byte)243, (byte)210,
        (byte)205,  (byte)12,  (byte)19, (byte)236,  (byte)95, (byte)151,  (byte)68,  (byte)23,
        (byte)196, (byte)167, (byte)126,  (byte)61, (byte)100,  (byte)93,  (byte)25, (byte)115,
        (byte)96, (byte)129,  (byte)79, (byte)220,  (byte)34,  (byte)42, (byte)144, (byte)136,
        (byte)70, (byte)238, (byte)184,  (byte)20, (byte)222,  (byte)94,  (byte)11, (byte)219,
        (byte)224,  (byte)50,  (byte)58,  (byte)10,  (byte)73,   (byte)6,  (byte)36,  (byte)92,
        (byte)194, (byte)211, (byte)172,  (byte)98, (byte)145, (byte)149, (byte)228, (byte)121,
        (byte)231, (byte)200,  (byte)55, (byte)109, (byte)141, (byte)213,  (byte)78, (byte)169,
        (byte)108,  (byte)86, (byte)244, (byte)234, (byte)101, (byte)122, (byte)174,   (byte)8,
        (byte)186, (byte)120,  (byte)37,  (byte)46,  (byte)28, (byte)166, (byte)180, (byte)198,
        (byte)232, (byte)221, (byte)116,  (byte)31,  (byte)75, (byte)189, (byte)139, (byte)138,
        (byte)112,  (byte)62, (byte)181, (byte)102,  (byte)72,   (byte)3, (byte)246,  (byte)14,
        (byte)97,  (byte)53,  (byte)87, (byte)185, (byte)134, (byte)193,  (byte)29, (byte)158,
        (byte)225, (byte)248, (byte)152,  (byte)17, (byte)105, (byte)217, (byte)142, (byte)148,
        (byte)155,  (byte)30, (byte)135, (byte)233, (byte)206,  (byte)85,  (byte)40, (byte)223,
        (byte)140, (byte)161, (byte)137,  (byte)13, (byte)191, (byte)230,  (byte)66, (byte)104,
        (byte)65, (byte)153,  (byte)45,  (byte)15, (byte)176,  (byte)84, (byte)187,  (byte)22,
    };
    
    private static final int[] rcon = {
         0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36, 0x6c, 0xd8, 0xab, 0x4d, 0x9a,
         0x2f, 0x5e, 0xbc, 0x63, 0xc6, 0x97, 0x35, 0x6a, 0xd4, 0xb3, 0x7d, 0xfa, 0xef, 0xc5, 0x91 };
	
    private static final int[] T0 =
    {
     0xa56363c6, 0x847c7cf8, 0x997777ee, 0x8d7b7bf6, 0x0df2f2ff, 
     0xbd6b6bd6, 0xb16f6fde, 0x54c5c591, 0x50303060, 0x03010102, 
     0xa96767ce, 0x7d2b2b56, 0x19fefee7, 0x62d7d7b5, 0xe6abab4d, 
     0x9a7676ec, 0x45caca8f, 0x9d82821f, 0x40c9c989, 0x877d7dfa, 
     0x15fafaef, 0xeb5959b2, 0xc947478e, 0x0bf0f0fb, 0xecadad41, 
     0x67d4d4b3, 0xfda2a25f, 0xeaafaf45, 0xbf9c9c23, 0xf7a4a453, 
     0x967272e4, 0x5bc0c09b, 0xc2b7b775, 0x1cfdfde1, 0xae93933d, 
     0x6a26264c, 0x5a36366c, 0x413f3f7e, 0x02f7f7f5, 0x4fcccc83, 
     0x5c343468, 0xf4a5a551, 0x34e5e5d1, 0x08f1f1f9, 0x937171e2, 
     0x73d8d8ab, 0x53313162, 0x3f15152a, 0x0c040408, 0x52c7c795, 
     0x65232346, 0x5ec3c39d, 0x28181830, 0xa1969637, 0x0f05050a, 
     0xb59a9a2f, 0x0907070e, 0x36121224, 0x9b80801b, 0x3de2e2df, 
     0x26ebebcd, 0x6927274e, 0xcdb2b27f, 0x9f7575ea, 0x1b090912, 
     0x9e83831d, 0x742c2c58, 0x2e1a1a34, 0x2d1b1b36, 0xb26e6edc, 
     0xee5a5ab4, 0xfba0a05b, 0xf65252a4, 0x4d3b3b76, 0x61d6d6b7, 
     0xceb3b37d, 0x7b292952, 0x3ee3e3dd, 0x712f2f5e, 0x97848413, 
     0xf55353a6, 0x68d1d1b9, 0x00000000, 0x2cededc1, 0x60202040, 
     0x1ffcfce3, 0xc8b1b179, 0xed5b5bb6, 0xbe6a6ad4, 0x46cbcb8d, 
     0xd9bebe67, 0x4b393972, 0xde4a4a94, 0xd44c4c98, 0xe85858b0, 
     0x4acfcf85, 0x6bd0d0bb, 0x2aefefc5, 0xe5aaaa4f, 0x16fbfbed, 
     0xc5434386, 0xd74d4d9a, 0x55333366, 0x94858511, 0xcf45458a, 
     0x10f9f9e9, 0x06020204, 0x817f7ffe, 0xf05050a0, 0x443c3c78, 
     0xba9f9f25, 0xe3a8a84b, 0xf35151a2, 0xfea3a35d, 0xc0404080, 
     0x8a8f8f05, 0xad92923f, 0xbc9d9d21, 0x48383870, 0x04f5f5f1, 
     0xdfbcbc63, 0xc1b6b677, 0x75dadaaf, 0x63212142, 0x30101020, 
     0x1affffe5, 0x0ef3f3fd, 0x6dd2d2bf, 0x4ccdcd81, 0x140c0c18, 
     0x35131326, 0x2fececc3, 0xe15f5fbe, 0xa2979735, 0xcc444488, 
     0x3917172e, 0x57c4c493, 0xf2a7a755, 0x827e7efc, 0x473d3d7a, 
     0xac6464c8, 0xe75d5dba, 0x2b191932, 0x957373e6, 0xa06060c0, 
     0x98818119, 0xd14f4f9e, 0x7fdcdca3, 0x66222244, 0x7e2a2a54, 
     0xab90903b, 0x8388880b, 0xca46468c, 0x29eeeec7, 0xd3b8b86b, 
     0x3c141428, 0x79dedea7, 0xe25e5ebc, 0x1d0b0b16, 0x76dbdbad, 
     0x3be0e0db, 0x56323264, 0x4e3a3a74, 0x1e0a0a14, 0xdb494992, 
     0x0a06060c, 0x6c242448, 0xe45c5cb8, 0x5dc2c29f, 0x6ed3d3bd, 
     0xefacac43, 0xa66262c4, 0xa8919139, 0xa4959531, 0x37e4e4d3, 
     0x8b7979f2, 0x32e7e7d5, 0x43c8c88b, 0x5937376e, 0xb76d6dda, 
     0x8c8d8d01, 0x64d5d5b1, 0xd24e4e9c, 0xe0a9a949, 0xb46c6cd8, 
     0xfa5656ac, 0x07f4f4f3, 0x25eaeacf, 0xaf6565ca, 0x8e7a7af4, 
     0xe9aeae47, 0x18080810, 0xd5baba6f, 0x887878f0, 0x6f25254a, 
     0x722e2e5c, 0x241c1c38, 0xf1a6a657, 0xc7b4b473, 0x51c6c697, 
     0x23e8e8cb, 0x7cdddda1, 0x9c7474e8, 0x211f1f3e, 0xdd4b4b96, 
     0xdcbdbd61, 0x868b8b0d, 0x858a8a0f, 0x907070e0, 0x423e3e7c, 
     0xc4b5b571, 0xaa6666cc, 0xd8484890, 0x05030306, 0x01f6f6f7, 
     0x120e0e1c, 0xa36161c2, 0x5f35356a, 0xf95757ae, 0xd0b9b969, 
     0x91868617, 0x58c1c199, 0x271d1d3a, 0xb99e9e27, 0x38e1e1d9, 
     0x13f8f8eb, 0xb398982b, 0x33111122, 0xbb6969d2, 0x70d9d9a9, 
     0x898e8e07, 0xa7949433, 0xb69b9b2d, 0x221e1e3c, 0x92878715, 
     0x20e9e9c9, 0x49cece87, 0xff5555aa, 0x78282850, 0x7adfdfa5, 
     0x8f8c8c03, 0xf8a1a159, 0x80898909, 0x170d0d1a, 0xdabfbf65, 
     0x31e6e6d7, 0xc6424284, 0xb86868d0, 0xc3414182, 0xb0999929, 
     0x772d2d5a, 0x110f0f1e, 0xcbb0b07b, 0xfc5454a8, 0xd6bbbb6d, 
     0x3a16162c};
    
}
