/*************************************************************************************
  * 作   者： 季健国
  * 说   明：AES CBC模式 128位秘钥 16字节
  * QQ     ： 181589805
 *************************************************************************************/
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Security.Cryptography;
using System.IO;

namespace Ant.Service.Utility
{

    /// <summary>
    /// ASE加解密
    /// </summary>
    public class AESHelper
    {
        public enum KeySize { Bits128, Bits192, Bits256 };  // key size, in bits, for construtor

        private int Nb;         // block size in 32-bit words.  Always 4 for AES.  (128 bits).
        private int Nk;         // key size in 32-bit words.  4, 6, 8.  (128, 192, 256 bits).
        private int Nr;         // number of rounds. 10, 12, 14.

        private byte[] key;     // the seed key. size will be 4 * keySize from ctor.
        private byte[,] Sbox;   // Substitution box
        private byte[,] iSbox;  // inverse Substitution box 
        private byte[,] w;      // key schedule array. 
        private byte[,] Rcon;   // Round constants.
        private byte[,] State;  // State matrix

        public AESHelper(KeySize keySize, byte[] keyBytes)
        {
            SetNbNkNr(keySize);

            this.key = new byte[this.Nk * 4];  // 16, 24, 32 bytes
            //keyBytes.CopyTo(this.key, 0); //改写为讲keyBytes的前Nk*4位存入key，不足的话用0补齐
            for (int i = 0; i < Nk * 4; ++i)
                if (i < keyBytes.Length)
                    this.key[i] = keyBytes[i];
                else
                    this.key[i] = 0;

            BuildSbox();
            BuildInvSbox();
            BuildRcon();
            KeyExpansion();  // expand the seed key into a key schedule and store in w

        }  // Aes constructor

        public void Cipher(byte[] input, byte[] output)  // encipher 16-bit input
        {
            // state = input
            this.State = new byte[4, Nb];  // always [4,4]
            for (int i = 0; i < (4 * Nb); ++i)
            {
                this.State[i % 4, i / 4] = input[i];
            }

            AddRoundKey(0);

            for (int round = 1; round <= (Nr - 1); ++round)  // main round loop
            {
                SubBytes();
                ShiftRows();
                MixColumns();
                AddRoundKey(round);
            }  // main round loop

            SubBytes();
            ShiftRows();
            AddRoundKey(Nr);

            // output = state
            for (int i = 0; i < (4 * Nb); ++i)
            {
                output[i] = this.State[i % 4, i / 4];
            }

        }  // Cipher()  加密  每一轮都经历了 SubBytes, ShiftRows, MixColumns 和 AddRoundKey 四个环节，但是最后一轮没有 MixColumns 环节

        public void InvCipher(byte[] input, byte[] output)  // decipher 16-bit input
        {
            // state = input
            this.State = new byte[4, Nb];  // always [4,4]
            for (int i = 0; i < (4 * Nb); ++i)
            {
                this.State[i % 4, i / 4] = input[i];
            }

            AddRoundKey(Nr);

            for (int round = Nr - 1; round >= 1; --round)  // main round loop
            {
                InvShiftRows();
                InvSubBytes();
                AddRoundKey(round);
                InvMixColumns();
            }  // end main round loop for InvCipher

            InvShiftRows();
            InvSubBytes();
            AddRoundKey(0);

            // output = state
            for (int i = 0; i < (4 * Nb); ++i)
            {
                output[i] = this.State[i % 4, i / 4];
            }

        }  // InvCipher()  解密  每一轮都经历了 invShiftRows, inSubBytes, AddRoundKey 和 invMixColumns 四个环节，但是最后一轮没有 invMixColumns 环节

        private void SetNbNkNr(KeySize keySize)
        {
            this.Nb = 4;     // block size always = 4 words = 16 bytes = 128 bits for AES

            if (keySize == KeySize.Bits128)
            {
                this.Nk = 4;   // key size = 4 words = 16 bytes = 128 bits
                this.Nr = 10;  // rounds for algorithm = 10
            }
            else if (keySize == KeySize.Bits192)
            {
                this.Nk = 6;   // 6 words = 24 bytes = 192 bits
                this.Nr = 12;
            }
            else if (keySize == KeySize.Bits256)
            {
                this.Nk = 8;   // 8 words = 32 bytes = 256 bits
                this.Nr = 14;
            }
        }  // SetNbNkNr()

        private void BuildSbox()
        {
            this.Sbox = new byte[16, 16] {  // populate the Sbox matrix
              /* 0     1     2     3     4     5     6     7     8     9     a     b     c     d     e     f */
        /*0*/  {0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76},
        /*1*/  {0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0},
        /*2*/  {0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15},
        /*3*/  {0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75},
        /*4*/  {0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84},
        /*5*/  {0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf},
        /*6*/  {0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8},
        /*7*/  {0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2},
        /*8*/  {0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73},
        /*9*/  {0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb},
        /*a*/  {0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79},
        /*b*/  {0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08},
        /*c*/  {0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a},
        /*d*/  {0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e},
        /*e*/  {0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf},
        /*f*/  {0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16} };

        }  // BuildSbox() 用于加密过程中的字节代换运算

        private void BuildInvSbox()
        {
            this.iSbox = new byte[16, 16] {  // populate the iSbox matrix
              /* 0     1     2     3     4     5     6     7     8     9     a     b     c     d     e     f */
        /*0*/  {0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38, 0xbf, 0x40, 0xa3, 0x9e, 0x81, 0xf3, 0xd7, 0xfb},
        /*1*/  {0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f, 0xff, 0x87, 0x34, 0x8e, 0x43, 0x44, 0xc4, 0xde, 0xe9, 0xcb},
        /*2*/  {0x54, 0x7b, 0x94, 0x32, 0xa6, 0xc2, 0x23, 0x3d, 0xee, 0x4c, 0x95, 0x0b, 0x42, 0xfa, 0xc3, 0x4e},
        /*3*/  {0x08, 0x2e, 0xa1, 0x66, 0x28, 0xd9, 0x24, 0xb2, 0x76, 0x5b, 0xa2, 0x49, 0x6d, 0x8b, 0xd1, 0x25},
        /*4*/  {0x72, 0xf8, 0xf6, 0x64, 0x86, 0x68, 0x98, 0x16, 0xd4, 0xa4, 0x5c, 0xcc, 0x5d, 0x65, 0xb6, 0x92},
        /*5*/  {0x6c, 0x70, 0x48, 0x50, 0xfd, 0xed, 0xb9, 0xda, 0x5e, 0x15, 0x46, 0x57, 0xa7, 0x8d, 0x9d, 0x84},
        /*6*/  {0x90, 0xd8, 0xab, 0x00, 0x8c, 0xbc, 0xd3, 0x0a, 0xf7, 0xe4, 0x58, 0x05, 0xb8, 0xb3, 0x45, 0x06},
        /*7*/  {0xd0, 0x2c, 0x1e, 0x8f, 0xca, 0x3f, 0x0f, 0x02, 0xc1, 0xaf, 0xbd, 0x03, 0x01, 0x13, 0x8a, 0x6b},
        /*8*/  {0x3a, 0x91, 0x11, 0x41, 0x4f, 0x67, 0xdc, 0xea, 0x97, 0xf2, 0xcf, 0xce, 0xf0, 0xb4, 0xe6, 0x73},
        /*9*/  {0x96, 0xac, 0x74, 0x22, 0xe7, 0xad, 0x35, 0x85, 0xe2, 0xf9, 0x37, 0xe8, 0x1c, 0x75, 0xdf, 0x6e},
        /*a*/  {0x47, 0xf1, 0x1a, 0x71, 0x1d, 0x29, 0xc5, 0x89, 0x6f, 0xb7, 0x62, 0x0e, 0xaa, 0x18, 0xbe, 0x1b},
        /*b*/  {0xfc, 0x56, 0x3e, 0x4b, 0xc6, 0xd2, 0x79, 0x20, 0x9a, 0xdb, 0xc0, 0xfe, 0x78, 0xcd, 0x5a, 0xf4},
        /*c*/  {0x1f, 0xdd, 0xa8, 0x33, 0x88, 0x07, 0xc7, 0x31, 0xb1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xec, 0x5f},
        /*d*/  {0x60, 0x51, 0x7f, 0xa9, 0x19, 0xb5, 0x4a, 0x0d, 0x2d, 0xe5, 0x7a, 0x9f, 0x93, 0xc9, 0x9c, 0xef},
        /*e*/  {0xa0, 0xe0, 0x3b, 0x4d, 0xae, 0x2a, 0xf5, 0xb0, 0xc8, 0xeb, 0xbb, 0x3c, 0x83, 0x53, 0x99, 0x61},
        /*f*/  {0x17, 0x2b, 0x04, 0x7e, 0xba, 0x77, 0xd6, 0x26, 0xe1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0c, 0x7d} };

        }  // BuildInvSbox()  用于解密过程中的逆字节代换运算

        private void BuildRcon()
        {
            this.Rcon = new byte[11, 4] { {0x00, 0x00, 0x00, 0x00},
                                       {0x01, 0x00, 0x00, 0x00},
                                       {0x02, 0x00, 0x00, 0x00},
                                       {0x04, 0x00, 0x00, 0x00},
                                       {0x08, 0x00, 0x00, 0x00},
                                       {0x10, 0x00, 0x00, 0x00},
                                       {0x20, 0x00, 0x00, 0x00},
                                       {0x40, 0x00, 0x00, 0x00},
                                       {0x80, 0x00, 0x00, 0x00},
                                       {0x1b, 0x00, 0x00, 0x00},
                                       {0x36, 0x00, 0x00, 0x00} };
        }  // BuildRcon()

        private void AddRoundKey(int round)
        {

            for (int r = 0; r < 4; ++r)
            {
                for (int c = 0; c < 4; ++c)
                {
                    this.State[r, c] = (byte)((int)this.State[r, c] ^ (int)w[(round * 4) + c, r]);
                }
            }
        }  // AddRoundKey()  轮密钥加法变换

        private void SubBytes()
        {
            for (int r = 0; r < 4; ++r)
            {
                for (int c = 0; c < 4; ++c)
                {
                    this.State[r, c] = this.Sbox[(this.State[r, c] >> 4), (this.State[r, c] & 0x0f)];
                }
            }
        }  // SubBytes  字节代替变换

        private void InvSubBytes()
        {
            for (int r = 0; r < 4; ++r)
            {
                for (int c = 0; c < 4; ++c)
                {
                    this.State[r, c] = this.iSbox[(this.State[r, c] >> 4), (this.State[r, c] & 0x0f)];
                }
            }
        }  // InvSubBytes  逆字节代替变换

        private void ShiftRows()
        {
            byte[,] temp = new byte[4, 4];
            for (int r = 0; r < 4; ++r)  // copy State into temp[]
            {
                for (int c = 0; c < 4; ++c)
                {
                    temp[r, c] = this.State[r, c];
                }
            }

            for (int r = 1; r < 4; ++r)  // shift temp into State
            {
                for (int c = 0; c < 4; ++c)
                {
                    this.State[r, c] = temp[r, (c + r) % Nb];
                }
            }
        }  // ShiftRows()  行位移变换

        private void InvShiftRows()
        {
            byte[,] temp = new byte[4, 4];
            for (int r = 0; r < 4; ++r)  // copy State into temp[]
            {
                for (int c = 0; c < 4; ++c)
                {
                    temp[r, c] = this.State[r, c];
                }
            }
            for (int r = 1; r < 4; ++r)  // shift temp into State
            {
                for (int c = 0; c < 4; ++c)
                {
                    this.State[r, (c + r) % Nb] = temp[r, c];
                }
            }
        }  // InvShiftRows()  逆行移位变换

        private void MixColumns()
        {
            byte[,] temp = new byte[4, 4];
            for (int r = 0; r < 4; ++r)  // copy State into temp[]
            {
                for (int c = 0; c < 4; ++c)
                {
                    temp[r, c] = this.State[r, c];
                }
            }

            for (int c = 0; c < 4; ++c)
            {
                this.State[0, c] = (byte)((int)gfmultby02(temp[0, c]) ^ (int)gfmultby03(temp[1, c]) ^
                                           (int)gfmultby01(temp[2, c]) ^ (int)gfmultby01(temp[3, c]));
                this.State[1, c] = (byte)((int)gfmultby01(temp[0, c]) ^ (int)gfmultby02(temp[1, c]) ^
                                           (int)gfmultby03(temp[2, c]) ^ (int)gfmultby01(temp[3, c]));
                this.State[2, c] = (byte)((int)gfmultby01(temp[0, c]) ^ (int)gfmultby01(temp[1, c]) ^
                                           (int)gfmultby02(temp[2, c]) ^ (int)gfmultby03(temp[3, c]));
                this.State[3, c] = (byte)((int)gfmultby03(temp[0, c]) ^ (int)gfmultby01(temp[1, c]) ^
                                           (int)gfmultby01(temp[2, c]) ^ (int)gfmultby02(temp[3, c]));
            }
        }  // MixColumns()  列混合变换

        private void InvMixColumns()
        {
            byte[,] temp = new byte[4, 4];
            for (int r = 0; r < 4; ++r)  // copy State into temp[]
            {
                for (int c = 0; c < 4; ++c)
                {
                    temp[r, c] = this.State[r, c];
                }
            }

            for (int c = 0; c < 4; ++c)
            {
                this.State[0, c] = (byte)((int)gfmultby0e(temp[0, c]) ^ (int)gfmultby0b(temp[1, c]) ^
                                           (int)gfmultby0d(temp[2, c]) ^ (int)gfmultby09(temp[3, c]));
                this.State[1, c] = (byte)((int)gfmultby09(temp[0, c]) ^ (int)gfmultby0e(temp[1, c]) ^
                                           (int)gfmultby0b(temp[2, c]) ^ (int)gfmultby0d(temp[3, c]));
                this.State[2, c] = (byte)((int)gfmultby0d(temp[0, c]) ^ (int)gfmultby09(temp[1, c]) ^
                                           (int)gfmultby0e(temp[2, c]) ^ (int)gfmultby0b(temp[3, c]));
                this.State[3, c] = (byte)((int)gfmultby0b(temp[0, c]) ^ (int)gfmultby0d(temp[1, c]) ^
                                           (int)gfmultby09(temp[2, c]) ^ (int)gfmultby0e(temp[3, c]));
            }
        }  // InvMixColumns()  逆列混合变换

        private static byte gfmultby01(byte b)
        {
            return b;
        }

        private static byte gfmultby02(byte b)
        {
            if (b < 0x80)
                return (byte)(int)(b << 1);
            else
                return (byte)((int)(b << 1) ^ (int)(0x1b));
        }

        private static byte gfmultby03(byte b)
        {
            return (byte)((int)gfmultby02(b) ^ (int)b);
        }

        private static byte gfmultby09(byte b)
        {
            return (byte)((int)gfmultby02(gfmultby02(gfmultby02(b))) ^
                           (int)b);
        }

        private static byte gfmultby0b(byte b)
        {
            return (byte)((int)gfmultby02(gfmultby02(gfmultby02(b))) ^
                           (int)gfmultby02(b) ^
                           (int)b);
        }

        private static byte gfmultby0d(byte b)
        {
            return (byte)((int)gfmultby02(gfmultby02(gfmultby02(b))) ^
                           (int)gfmultby02(gfmultby02(b)) ^
                           (int)(b));
        }

        private static byte gfmultby0e(byte b)
        {
            return (byte)((int)gfmultby02(gfmultby02(gfmultby02(b))) ^
                           (int)gfmultby02(gfmultby02(b)) ^
                           (int)gfmultby02(b));
        }

        private void KeyExpansion()
        {
            this.w = new byte[Nb * (Nr + 1), 4];  // 4 columns of bytes corresponds to a word

            for (int row = 0; row < Nk; ++row)
            {
                this.w[row, 0] = this.key[4 * row];
                this.w[row, 1] = this.key[4 * row + 1];
                this.w[row, 2] = this.key[4 * row + 2];
                this.w[row, 3] = this.key[4 * row + 3];
            }

            byte[] temp = new byte[4];

            for (int row = Nk; row < Nb * (Nr + 1); ++row)
            {
                temp[0] = this.w[row - 1, 0]; temp[1] = this.w[row - 1, 1];
                temp[2] = this.w[row - 1, 2]; temp[3] = this.w[row - 1, 3];

                if (row % Nk == 0)
                {
                    temp = SubWord(RotWord(temp));

                    temp[0] = (byte)((int)temp[0] ^ (int)this.Rcon[row / Nk, 0]);
                    temp[1] = (byte)((int)temp[1] ^ (int)this.Rcon[row / Nk, 1]);
                    temp[2] = (byte)((int)temp[2] ^ (int)this.Rcon[row / Nk, 2]);
                    temp[3] = (byte)((int)temp[3] ^ (int)this.Rcon[row / Nk, 3]);
                }
                else if (Nk > 6 && (row % Nk == 4))
                {
                    temp = SubWord(temp);
                }

                // w[row] = w[row-Nk] xor temp
                this.w[row, 0] = (byte)((int)this.w[row - Nk, 0] ^ (int)temp[0]);
                this.w[row, 1] = (byte)((int)this.w[row - Nk, 1] ^ (int)temp[1]);
                this.w[row, 2] = (byte)((int)this.w[row - Nk, 2] ^ (int)temp[2]);
                this.w[row, 3] = (byte)((int)this.w[row - Nk, 3] ^ (int)temp[3]);

            }  // for loop
        }  // KeyExpansion()  密钥扩展

        private byte[] SubWord(byte[] word)
        {
            byte[] result = new byte[4];
            result[0] = this.Sbox[word[0] >> 4, word[0] & 0x0f];
            result[1] = this.Sbox[word[1] >> 4, word[1] & 0x0f];
            result[2] = this.Sbox[word[2] >> 4, word[2] & 0x0f];
            result[3] = this.Sbox[word[3] >> 4, word[3] & 0x0f];
            return result;
        }

        private byte[] RotWord(byte[] word)
        {
            byte[] result = new byte[4];
            result[0] = word[1];
            result[1] = word[2];
            result[2] = word[3];
            result[3] = word[0];
            return result;
        }

        public void Dump()
        {
            //Console.WriteLine("Nb = " + Nb + " Nk = " + Nk + " Nr = " + Nr);
            //Console.WriteLine("\nThe key is \n" + DumpKey() );
            //Console.WriteLine("\nThe Sbox is \n" + DumpTwoByTwo(Sbox));
            //Console.WriteLine("\nThe w array is \n" + DumpTwoByTwo(w));
            //Console.WriteLine("\nThe State array is \n" + DumpTwoByTwo(State));
        }

        public string DumpKey()
        {
            string s = "";
            for (int i = 0; i < key.Length; ++i)
                s += key[i].ToString("x2") + " ";
            return s;
        }

        public string DumpTwoByTwo(byte[,] a)
        {
            string s = "";
            for (int r = 0; r < a.GetLength(0); ++r)
            {
                s += "[" + r + "]" + " ";
                for (int c = 0; c < a.GetLength(1); ++c)
                {
                    s += a[r, c].ToString("x2") + " ";
                }
                s += "\n";
            }
            return s;
        }

    }  // class Aes
}