aes.cpp

/*
*/


#include "AES.h"
#include <cstdio>
#include <cstring>
#include <cassert>

AES::AES(unsigned char* key)
{
    unsigned char sBox[] =
    { /*  0    1    2    3    4    5    6    7    8    9    a    b    c    d    e    f */
        0x63,0x7c,0x77,0x7b,0xf2,0x6b,0x6f,0xc5,0x30,0x01,0x67,0x2b,0xfe,0xd7,0xab,0x76, /*0*/
        0xca,0x82,0xc9,0x7d,0xfa,0x59,0x47,0xf0,0xad,0xd4,0xa2,0xaf,0x9c,0xa4,0x72,0xc0, /*1*/
        0xb7,0xfd,0x93,0x26,0x36,0x3f,0xf7,0xcc,0x34,0xa5,0xe5,0xf1,0x71,0xd8,0x31,0x15, /*2*/
        0x04,0xc7,0x23,0xc3,0x18,0x96,0x05,0x9a,0x07,0x12,0x80,0xe2,0xeb,0x27,0xb2,0x75, /*3*/
        0x09,0x83,0x2c,0x1a,0x1b,0x6e,0x5a,0xa0,0x52,0x3b,0xd6,0xb3,0x29,0xe3,0x2f,0x84, /*4*/
        0x53,0xd1,0x00,0xed,0x20,0xfc,0xb1,0x5b,0x6a,0xcb,0xbe,0x39,0x4a,0x4c,0x58,0xcf, /*5*/
        0xd0,0xef,0xaa,0xfb,0x43,0x4d,0x33,0x85,0x45,0xf9,0x02,0x7f,0x50,0x3c,0x9f,0xa8, /*6*/
        0x51,0xa3,0x40,0x8f,0x92,0x9d,0x38,0xf5,0xbc,0xb6,0xda,0x21,0x10,0xff,0xf3,0xd2, /*7*/
        0xcd,0x0c,0x13,0xec,0x5f,0x97,0x44,0x17,0xc4,0xa7,0x7e,0x3d,0x64,0x5d,0x19,0x73, /*8*/
        0x60,0x81,0x4f,0xdc,0x22,0x2a,0x90,0x88,0x46,0xee,0xb8,0x14,0xde,0x5e,0x0b,0xdb, /*9*/
        0xe0,0x32,0x3a,0x0a,0x49,0x06,0x24,0x5c,0xc2,0xd3,0xac,0x62,0x91,0x95,0xe4,0x79, /*a*/
        0xe7,0xc8,0x37,0x6d,0x8d,0xd5,0x4e,0xa9,0x6c,0x56,0xf4,0xea,0x65,0x7a,0xae,0x08, /*b*/
        0xba,0x78,0x25,0x2e,0x1c,0xa6,0xb4,0xc6,0xe8,0xdd,0x74,0x1f,0x4b,0xbd,0x8b,0x8a, /*c*/
        0x70,0x3e,0xb5,0x66,0x48,0x03,0xf6,0x0e,0x61,0x35,0x57,0xb9,0x86,0xc1,0x1d,0x9e, /*d*/
        0xe1,0xf8,0x98,0x11,0x69,0xd9,0x8e,0x94,0x9b,0x1e,0x87,0xe9,0xce,0x55,0x28,0xdf, /*e*/
        0x8c,0xa1,0x89,0x0d,0xbf,0xe6,0x42,0x68,0x41,0x99,0x2d,0x0f,0xb0,0x54,0xbb,0x16  /*f*/
    };
    unsigned char invsBox[256] =
    { /*  0    1    2    3    4    5    6    7    8    9    a    b    c    d    e    f  */
        0x52,0x09,0x6a,0xd5,0x30,0x36,0xa5,0x38,0xbf,0x40,0xa3,0x9e,0x81,0xf3,0xd7,0xfb, /*0*/
        0x7c,0xe3,0x39,0x82,0x9b,0x2f,0xff,0x87,0x34,0x8e,0x43,0x44,0xc4,0xde,0xe9,0xcb, /*1*/
        0x54,0x7b,0x94,0x32,0xa6,0xc2,0x23,0x3d,0xee,0x4c,0x95,0x0b,0x42,0xfa,0xc3,0x4e, /*2*/
        0x08,0x2e,0xa1,0x66,0x28,0xd9,0x24,0xb2,0x76,0x5b,0xa2,0x49,0x6d,0x8b,0xd1,0x25, /*3*/
        0x72,0xf8,0xf6,0x64,0x86,0x68,0x98,0x16,0xd4,0xa4,0x5c,0xcc,0x5d,0x65,0xb6,0x92, /*4*/
        0x6c,0x70,0x48,0x50,0xfd,0xed,0xb9,0xda,0x5e,0x15,0x46,0x57,0xa7,0x8d,0x9d,0x84, /*5*/
        0x90,0xd8,0xab,0x00,0x8c,0xbc,0xd3,0x0a,0xf7,0xe4,0x58,0x05,0xb8,0xb3,0x45,0x06, /*6*/
        0xd0,0x2c,0x1e,0x8f,0xca,0x3f,0x0f,0x02,0xc1,0xaf,0xbd,0x03,0x01,0x13,0x8a,0x6b, /*7*/
        0x3a,0x91,0x11,0x41,0x4f,0x67,0xdc,0xea,0x97,0xf2,0xcf,0xce,0xf0,0xb4,0xe6,0x73, /*8*/
        0x96,0xac,0x74,0x22,0xe7,0xad,0x35,0x85,0xe2,0xf9,0x37,0xe8,0x1c,0x75,0xdf,0x6e, /*9*/
        0x47,0xf1,0x1a,0x71,0x1d,0x29,0xc5,0x89,0x6f,0xb7,0x62,0x0e,0xaa,0x18,0xbe,0x1b, /*a*/
        0xfc,0x56,0x3e,0x4b,0xc6,0xd2,0x79,0x20,0x9a,0xdb,0xc0,0xfe,0x78,0xcd,0x5a,0xf4, /*b*/
        0x1f,0xdd,0xa8,0x33,0x88,0x07,0xc7,0x31,0xb1,0x12,0x10,0x59,0x27,0x80,0xec,0x5f, /*c*/
        0x60,0x51,0x7f,0xa9,0x19,0xb5,0x4a,0x0d,0x2d,0xe5,0x7a,0x9f,0x93,0xc9,0x9c,0xef, /*d*/
        0xa0,0xe0,0x3b,0x4d,0xae,0x2a,0xf5,0xb0,0xc8,0xeb,0xbb,0x3c,0x83,0x53,0x99,0x61, /*e*/
        0x17,0x2b,0x04,0x7e,0xba,0x77,0xd6,0x26,0xe1,0x69,0x14,0x63,0x55,0x21,0x0c,0x7d  /*f*/
    };
    memcpy(Sbox, sBox, 256);
    memcpy(InvSbox, invsBox, 256);
    if (key != NULL) {
        KeyExpansion(key, w);
    }
}

AES::~AES()
{

}

void AES::SetKey (unsigned char *key) {
    KeyExpansion(key, w);
}

unsigned char* AES::Cipher(unsigned char* input, unsigned char *output)
{
    unsigned char state[4][4];
    int i,r,c;

    for(r=0; r<4; r++)
    {
        for(c=0; c<4 ;c++)
        {
            state[r][c] = input[c*4+r];
        }
    }

    AddRoundKey(state,w[0]);

    for(i=1; i<=10; i++)
    {
        SubBytes(state);
        ShiftRows(state);
        if(i!=10)MixColumns(state);
        AddRoundKey(state,w[i]);
    }

    for(r=0; r<4; r++)
    {
        for(c=0; c<4 ;c++)
        {
            output[c*4+r] = state[r][c];
        }
    }

    return output;
}

unsigned char* AES::InvCipher(unsigned char* input, unsigned char *output)
{
    unsigned char state[4][4];
    int i,r,c;

    for(r=0; r<4; r++)
    {
        for(c=0; c<4 ;c++)
        {
            state[r][c] = input[c*4+r];
        }
    }

    AddRoundKey(state, w[10]);
    for(i=9; i>=0; i--)
    {
        InvShiftRows(state);
        InvSubBytes(state);
        AddRoundKey(state, w[i]);
        if(i)
        {
            InvMixColumns(state);
        }
    }

    for(r=0; r<4; r++)
    {
        for(c=0; c<4 ;c++)
        {
            output[c*4+r] = state[r][c];
        }
    }
    return output;
}

void* AES::Cipher(void* input,  void *output, int length)
{
    unsigned char* in = (unsigned char*) input;
    unsigned char* out = (unsigned char*) output;
    int i;
    if(!length)
    {
        while(*(in+length++));
        in = (unsigned char*) input;
    }
    for(i=0; i<length; i+=16)
    {
        Cipher(in+i, out+i);
    }
    return output;
}

void* AES::InvCipher(void* input, void* output, int length)
{
    unsigned char* in = (unsigned char*) input;
    unsigned char* out = (unsigned char*) output;
    int i;
    for(i=0; i<length; i+=16)
    {
        InvCipher(in+i, out+i);
    }
    return output;
}

void AES::KeyExpansion(unsigned char* key, unsigned char w[][4][4])
{
    int i,j,r,c;
    unsigned char rc[] = {0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36};
    for(r=0; r<4; r++)
    {
        for(c=0; c<4; c++)
        {
            w[0][r][c] = key[r+c*4];
        }
    }
    for(i=1; i<=10; i++)
    {
        for(j=0; j<4; j++)
        {
            unsigned char t[4];
            for(r=0; r<4; r++)
            {
                t[r] = j ? w[i][r][j-1] : w[i-1][r][3];
            }
            if(j == 0)
            {
                unsigned char temp = t[0];
                for(r=0; r<3; r++)
                {
                    t[r] = Sbox[t[(r+1)%4]];
                }
                t[3] = Sbox[temp];
                t[0] ^= rc[i-1];
            }
            for(r=0; r<4; r++)
            {
                w[i][r][j] = w[i-1][r][j] ^ t[r];
            }
        }
    }
}

unsigned char AES::FFmul(unsigned char a, unsigned char b)
{
    unsigned char bw[4];
    unsigned char res=0;
    int i;
    bw[0] = b;
    for(i=1; i<4; i++)
    {
        bw[i] = bw[i-1]<<1;
        if(bw[i-1]&0x80)
        {
            bw[i]^=0x1b;
        }
    }
    for(i=0; i<4; i++)
    {
        if((a>>i)&0x01)
        {
            res ^= bw[i];
        }
    }
    return res;
}

void AES::SubBytes(unsigned char state[][4])
{
    int r,c;
    for(r=0; r<4; r++)
    {
        for(c=0; c<4; c++)
        {
            state[r][c] = Sbox[state[r][c]];
        }
    }
}

void AES::ShiftRows(unsigned char state[][4])
{
    unsigned char t[4];
    int r,c;
    for(r=1; r<4; r++)
    {
        for(c=0; c<4; c++)
        {
            t[c] = state[r][(c+r)%4];
        }
        for(c=0; c<4; c++)
        {
            state[r][c] = t[c];
        }
    }
}

void AES::MixColumns(unsigned char state[][4])
{
    unsigned char t[4];
    int r,c;
    for(c=0; c< 4; c++)
    {
        for(r=0; r<4; r++)
        {
            t[r] = state[r][c];
        }
        for(r=0; r<4; r++)
        {
            state[r][c] = FFmul(0x02, t[r])
                        ^ FFmul(0x03, t[(r+1)%4])
                        ^ FFmul(0x01, t[(r+2)%4])
                        ^ FFmul(0x01, t[(r+3)%4]);
        }
    }
}

void AES::AddRoundKey(unsigned char state[][4], unsigned char k[][4])
{
    int r,c;
    for(c=0; c<4; c++)
    {
        for(r=0; r<4; r++)
        {
            state[r][c] ^= k[r][c];
        }
    }
}

void AES::InvSubBytes(unsigned char state[][4])
{
    int r,c;
    for(r=0; r<4; r++)
    {
        for(c=0; c<4; c++)
        {
            state[r][c] = InvSbox[state[r][c]];
        }
    }
}

void AES::InvShiftRows(unsigned char state[][4])
{
    unsigned char t[4];
    int r,c;
    for(r=1; r<4; r++)
    {
        for(c=0; c<4; c++)
        {
            t[c] = state[r][(c-r+4)%4];
        }
        for(c=0; c<4; c++)
        {
            state[r][c] = t[c];
        }
    }
}

void AES::InvMixColumns(unsigned char state[][4])
{
    unsigned char t[4];
    int r,c;
    for(c=0; c< 4; c++)
    {
        for(r=0; r<4; r++)
        {
            t[r] = state[r][c];
        }
        for(r=0; r<4; r++)
        {
            state[r][c] = FFmul(0x0e, t[r])
                        ^ FFmul(0x0b, t[(r+1)%4])
                        ^ FFmul(0x0d, t[(r+2)%4])
                        ^ FFmul(0x09, t[(r+3)%4]);
        }
    }
}

/**************************************************************/
//AESModeOfOperation

AESModeOfOperation::AESModeOfOperation() {
    m_mode = MODE_ECB;
    m_aes = NULL;
    memset(m_key, 0, 16);
    memset(m_iv, 0, 16);
    m_aes = new AES(m_key);
    assert(m_aes != NULL);
}

AESModeOfOperation::~AESModeOfOperation() {
    delete m_aes;
}

void AESModeOfOperation::set_mode(AESMode_t _mode) {
    m_mode = _mode;
}

void AESModeOfOperation::set_key(unsigned char *_key) {
    assert(_key != NULL);
    memcpy(m_key, _key, 16);
    m_aes->SetKey(m_key);
}
void AESModeOfOperation::set_iv(unsigned char *_iv) {
    assert(_iv != NULL);
    memcpy(m_iv, _iv, 16);
}

int AESModeOfOperation::Encrypt(unsigned char *_in, int _length, unsigned char *_out) {
    bool first_round = true;
    int rounds = 0;
    int start = 0;
    int end = 0;
    unsigned char input[16] = {0};
    unsigned char output[16] = {0};
    unsigned char ciphertext[16] = {0};
    unsigned char* cipherout = new unsigned char[_length+16];
    unsigned char plaintext[16] = {0};
    int co_index = 0;
    // 1. get rounds
    if ( _length % 16 == 0) {
        rounds = _length / 16;
    } else {
        rounds = _length / 16 + 1;
    }
    // 2. for all rounds
    for (int j = 0; j < rounds; ++j) {
        start = j*16;
        end = j*16 + 16;
        if (end > _length) end = _length;	// end of input
        // 3. copyt input to m_plaintext
        memset(plaintext, 0, 16);
        memcpy(plaintext, _in + start, end - start);
        // 4. handle all modes
        if (m_mode == MODE_CFB) {
            if (first_round == true) {
                m_aes->Cipher(m_iv, output);
                first_round = false;
            } else {
                m_aes->Cipher(input,output);
            }
            for (int i = 0; i < 16; ++i) {
                if ( (end - start) - 1 < i) {
                    ciphertext[i] = 0 ^ output[i];
                } else {
                    ciphertext[i] = plaintext[i] ^ output[i];
                }
            }
            for (int k = 0 ; k < end - start; ++k) {
                cipherout[co_index++] = ciphertext[k];
            }
            //memset(input,0, 16);
            memcpy(input,ciphertext, 16);
        } else if (m_mode == MODE_OFB) {			// MODE_OFB
            if (first_round == true) {
                m_aes->Cipher(m_iv,output); //
                first_round = false;
            } else {
                m_aes->Cipher(input, output);
            }
            // ciphertext = plaintext ^ output
            for (int i = 0; i < 16; ++i) {
                if ( (end - start) - 1 < i) {
                    ciphertext[i] = 0 ^ output[i];
                } else {
                    ciphertext[i] = plaintext[i] ^ output[i];
                }
            }
            //
            for (int k = 0; k < end - start; ++k) {
                cipherout[co_index++] = ciphertext[k];
            }
            //memset(input,0,16);
            memcpy(input, output, 16);
        } else if (m_mode == MODE_CBC) {			// MODE_CBC
            for (int i = 0; i < 16; ++i) {
                if (first_round == true) {
                    input[i] = plaintext[i] ^ m_iv[i];
                } else {
                    input[i] = plaintext[i] ^ ciphertext[i];
                }
            }
            first_round = false;
            m_aes->Cipher(input, ciphertext);
            for (int k = 0; k < end - start; ++k){
                cipherout[co_index++] = ciphertext[k];
            }

        } else if (m_mode == MODE_ECB) {
            // TODO:
        }
    }
    memcpy(_out, cipherout, co_index);
    delete[] cipherout;
    return co_index;
}

int AESModeOfOperation::Decrypt(unsigned char *_in, int _length, unsigned char *_out) {
    // TODO :
    bool first_round = true;
    int rounds = 0;
    unsigned char ciphertext[16] = {0};
    unsigned char input[16] = {0};
    unsigned char output[16] = {0};
    unsigned char plaintext[16] = {0};
    unsigned char* plainout = new unsigned char[_length + 16];
    int po_index = 0 ;
    if (_length % 16 == 0) {
        rounds = _length / 16;
    } else {
        rounds = _length / 16 + 1;
    }

    int start = 0;
    int end = 0;

    for (int j = 0; j < rounds; j++) {
        start = j * 16;
        end   = start + 16;
        if ( end > _length) {
            end = _length;
        }
        memset(ciphertext, 0, 16);
        memcpy(ciphertext, _in + start, end - start);
        if ( m_mode == MODE_CFB ) {
            if (first_round = true) {
                m_aes->Cipher(m_iv, output);
                first_round = false;
            } else {
                m_aes->Cipher(input, output);
            }
            for (int i = 0; i < 16; i++) {
                if ( end - start - 1 < i) {
                    plaintext[i] = output[i] ^ 0;
                } else {
                    plaintext[i] = output[i] ^ ciphertext[i];
                }
            }
            for (int k = 0; k < end - start; ++k) {
                plainout[po_index++] = plaintext[k];
            }
            //memset(input, 0, 16);
            memcpy(input, ciphertext, 16);
        } else if (m_mode == MODE_OFB) {
            if (first_round == true) {
                m_aes->Cipher(m_iv, output);
                first_round = false;
            } else {
                m_aes->Cipher(input, output);
            }
            for (int i = 0; i < 16; i++) {
                if ( end - start -1 < i) {
                    plaintext[i] = 0 ^ ciphertext[i];
                    first_round = false;
                } else {
                    plaintext[i] = output[i] ^ ciphertext[i];
                }
            }
            for (int k = 0; k < end - start; ++k) {
                plainout[po_index++] = plaintext[k];
            }
            memcpy(input, output, 16);
        } else if (m_mode == MODE_CBC) {
            m_aes->InvCipher(ciphertext, output);
            for (int i = 0; i < 16; ++i) {
                if ( first_round == true) {
                    plaintext[i] =  m_iv[i] ^  output[i];
                } else {
                    plaintext[i] = input[i] ^ output[i];
                }
            }
            first_round = false;
            for ( int k = 0; k < end - start; ++k) {
                plainout[po_index++] = plaintext[k];
            }
            memcpy(input, ciphertext, 16);
        } else {
            // TODO
        }
    }
    memcpy(_out, plainout, po_index);
    delete[] plainout;
    return po_index;
}