AES encryption/decryption (mode CBC-data block 128 bits-filling method pkcs5padding)

unsigned char FA(unsigned char b);
unsigned char FB(unsigned char b);
unsigned char FC(unsigned char b);
unsigned char FD(unsigned char b);
unsigned char FE(unsigned char b);
unsigned char Ff(unsigned char b);
void Cipher(unsigned char* input, unsigned char* output, unsigned char* w);//encryption
void InvCipher(unsigned char* input, unsigned char* output, unsigned char* w);//decryption

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

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


unsigned char FA(unsigned char b){<!-- -->if (b < 0x80) return (b <<1); else return ( (b << 1) ^ (0x1b) );}
unsigned char FB(unsigned char b){<!-- -->return FA(b) ^ b ;}
unsigned char FC(unsigned char b){<!-- -->return FA(FA(FA(b))) ^ b ;}
unsigned char FD(unsigned char b){<!-- -->return FA(FA(FA(b))) ^ FA(b) ^ b ;}
unsigned char FE(unsigned char b){<!-- -->return FA(FA(FA(b))) ^ FA(FA(b)) ^ b;}
unsigned char Ff(unsigned char b){<!-- -->return FA(FA(FA(b))) ^ FA(FA(b)) ^ FA(b);}

void Cipher(unsigned char* input, unsigned char* output, unsigned char* exp_key)
{<!-- -->
    int i,j;
    int round;
    unsigned char ttt[4*4];
    unsigned char State[4][4];
    for(i=0;i<16;i ++ ) State[i%4][i/4]=input[i];
    for(j=0;j<4;j + + )for(i=0;i<4;i + + )State[i][j]=State[i][j]^exp_key[4*j + i];
    for (round = 1; round <= 9; round ++ )
    {<!-- -->
        for(j=0;j<4;j + + )for(i=0;i<4;i + + )State[i][j]=AesSbox[State[i][j]];
        for(j=0;j<4;j + + )for(i=0;i<4;i + + )ttt[4*i + j]=State[i][j];
        for(i=1;i<4;i ++ )for(j=0;j<4;j ++ )
        {<!-- -->if(i==1)State[i][j]=ttt[4*i + (j + 1)%4];else if(i==2)State[i] [j]=ttt[4*i + (j + 2)%4]; else if(i==3)State[i][j]=ttt[4*i + (j + 3)%4]; }
        for(j=0;j<4;j + + ) for(i=0;i<4;i + + ) ttt[4*i + j]=State[i][j];
        for(j=0;j<4;j++)
        {<!-- -->
            State[0][j] = FA(ttt[0 + j]) ^ FB(ttt[4*1 + j]) ^ ttt[4*2 + j] ^ ttt[4*3 + j];
            State[1][j] = ttt[0 + j] ^ FA(ttt[4*1 + j]) ^ FB(ttt[4*2 + j]) ^ ttt[4*3 + j];
            State[2][j] = ttt[0 + j] ^ ttt[4*1 + j] ^ FA(ttt[4*2 + j]) ^ FB(ttt[4*3 + j]);
            State[3][j] = FB(ttt[0 + j]) ^ ttt[4*1 + j] ^ ttt[4*2 + j] ^ FA(ttt[4*3 + j]);
        }
        for(j=0;j<4;j ++ )for(i=0;i<4;i ++ )State[i][j]=State[i][j]^exp_key[4*(( round*4) + j) + i];
    }
    for(j=0;j<4;j + + )for(i=0;i<4;i + + )State[i][j]=AesSbox[State[i][j]];
    for(j=0;j<4;j + + )for(i=0;i<4;i + + )ttt[4*i + j]=State[i][j];
    for(i=1;i<4;i ++ )for(j=0;j<4;j ++ )
    {<!-- -->if(i==1)State[i][j]=ttt[4*i + (j + 1)%4];else if(i==2)State[i] [j]=ttt[4*i + (j + 2)%4]; else if(i==3)State[i][j]=ttt[4*i + (j + 3)%4]; }
    for(j=0;j<4;j++)for(i=0;i<4;i++)State[i][j]=State[i][j]^exp_key[4*(40 + j) + i];
    for ( i = 0; i < 16; i ++ ) output[i] = State[i%4][i/4];
}

//Aes decryption function
void InvCipher(unsigned char* input, unsigned char* output, unsigned char* exp_key)
{<!-- -->
    int round;
    int i,j;
    unsigned char ttt[4*4];
    unsigned char State[4][4];
    for ( i = 0; i < 16; i ++ )State[i % 4][ i / 4] = input[i];
    for(j=0;j<4;j++)for(i=0;i<4;i++)State[i][j]=State[i][j]^exp_key[4*(40 + j) + i];
    for (round = 9; round >= 1; round--)
    {<!-- -->
        for(j=0;j<4;j + + )for(i=0;i<4;i + + )ttt[4*i + j]=State[i][j];
        for(i=1;i<4;i ++ )for(j=0;j<4;j ++ )
        {<!-- -->if(i==1)State[i][j]=ttt[4*i + (j + 3)%4];else if(i==2)State[i] [j]=ttt[4*i + (j + 2)%4]; else if(i==3)State[i][j]=ttt[4*i + (j + 1)%4]; }
        for(j=0;j<4;j + + )for(i=0;i<4;i + + )State[i][j]=AesiSbox[State[i][j]];
        for(j=0;j<4;j ++ )for(i=0;i<4;i ++ )State[i][j]=State[i][j]^exp_key[4*(( round*4) + j) + i];
        for (i = 0; i < 4; i + + )for (j = 0; j < 4; j + + ) ttt[4*i + j] = State[i][j];
        for (j = 0; j < 4; j ++ )
        {<!-- -->
            State[0][j] = Ff(ttt[j]) ^ FD(ttt[4 + j]) ^ FE(ttt[4*2 + j]) ^ FC(ttt[4*3 + j]);
            State[1][j] = FC(ttt[j]) ^ Ff(ttt[4 + j]) ^ FD(ttt[4*2 + j]) ^ FE(ttt[4*3 + j]);
            State[2][j] = FE(ttt[j]) ^ FC(ttt[4 + j]) ^ Ff(ttt[4*2 + j]) ^ FD(ttt[4*3 + j]);
            State[3][j] = FD(ttt[j]) ^ FE(ttt[4 + j]) ^ FC(ttt[4*2 + j]) ^ Ff(ttt[4*3 + j]);
        }
    }
    for(j=0;j<4;j + + )for(i=0;i<4;i + + )ttt[4*i + j]=State[i][j];
    for(i=1;i<4;i ++ )for(j=0;j<4;j ++ )
    {<!-- -->if(i==1)State[i][j]=ttt[4*i + (j + 3)%4];else if(i==2)State[i] [j]=ttt[4*i + (j + 2)%4]; else if(i==3)State[i][j]=ttt[4*i + (j + 1)%4]; }
    for(j=0;j<4;j + + )for(i=0;i<4;i + + )State[i][j]=AesiSbox[State[i][j]];
    for(j=0;j<4;j + + )for(i=0;i<4;i + + )State[i][j]= State[i][j] ^ exp_key[4*j + i];
    for ( i = 0; i < 16; i ++ ) output[i] = State[i%4][i/4];
}

/**************************************************** ****
*Function function: AES encryption, mode CBC, data block 128 bits, padding method: pkcs5padding
* Parameters:
* input_buff: Array pointer that needs to be encrypted
* InputLen: byte length of encrypted data
* p_key: pointer to key data, 1~16 bytes in length
* output_buff: encryption result output pointer
*
* Return value: OutLength the encrypted output length
***************************************************** *****/
unsigned long AES128_CBC_Encrypt(unsigned char * input_buff, unsigned long InputLen, unsigned char * p_key, unsigned char * output_buff, unsigned char *iv)
{<!-- -->
    unsigned long OutLength=0;
    long i,j;
    unsigned char *lpCurInBuff=input_buff;
    unsigned char *lpCurOutBuff=output_buff;
    long blocknum=InputLen/16;
    long leftnum=InputLen;

    int row;
    unsigned char temp[4];
    unsigned char ex_key[16*15];
    for( row=0;row<4;row + + ) //Copy the seed key
    {<!-- -->
        ex_key[4*row + 0] = *(p_key + 4*row);
        ex_key[4*row + 1] = *(p_key + 4*row + 1);
        ex_key[4*row + 2] = *(p_key + 4*row + 2);
        ex_key[4*row + 3] = *(p_key + 4*row + 3);
    }
    for(row=4;row<44;row++)
    {<!-- -->
        temp[0]=ex_key[4*row-4]; //The previous column of the current column
        temp[1]=ex_key[4*row-3];
        temp[2]=ex_key[4*row-2];
        temp[3]=ex_key[4*row-1];
        if(row%4==0)
        {<!-- -->
            unsigned char exchange_buff=0;
            exchange_buff = temp[0];
            temp[0] = AesSbox[16*(temp[1] >> 4) + (temp[1] & 0x0f)];
            temp[1] = AesSbox[16*(temp[2] >> 4) + (temp[2] & 0x0f)];
            temp[2] = AesSbox[16*(temp[3] >> 4) + (temp[3] & 0x0f)];
            temp[3] = AesSbox[16*(exchange_buff >> 4) + (exchange_buff & 0x0f)];

            temp[0] = temp[0] ^ AesRcon[4*(row/4) + 0];
            temp[1] = temp[1] ^ AesRcon[4*(row/4) + 1];
            temp[2] = temp[2] ^ AesRcon[4*(row/4) + 2];
            temp[3] = temp[3] ^ AesRcon[4*(row/4) + 3];
        }
        ex_key[4*row + 0] = ex_key[4*(row-4) + 0] ^ temp[0] ;
        ex_key[4*row + 1] = ex_key[4*(row-4) + 1] ^ temp[1];
        ex_key[4*row + 2] = ex_key[4*(row-4) + 2] ^ temp[2] ;
        ex_key[4*row + 3] = ex_key[4*(row-4) + 3] ^ temp[3];
    }
    for( i=0;i<blocknum;i ++ )
    {<!-- -->
        for(j = 0; j < 16; j ++ )lpCurOutBuff[j] = lpCurInBuff[j] ^ iv[j];
        Cipher(lpCurOutBuff, lpCurOutBuff, ex_key);
        memcpy(iv, lpCurOutBuff, 16 );
        lpCurInBuff + =16;
        lpCurOutBuff + =16;
        OutLength + =16;
    }
    if(leftnum)
    {<!-- -->
        unsigned char inbuff[16];
        memset(inbuff,16-leftnum,16);
        memcpy(inbuff, lpCurInBuff, leftnum);
        for(j = 0; j < 16; j ++ )lpCurOutBuff[j] = inbuff[j] ^ iv[j];
        Cipher(lpCurOutBuff, lpCurOutBuff, ex_key);
        memcpy(iv, lpCurOutBuff, 16 );
        lpCurOutBuff + =16;
        OutLength + =16;
    }
    else
    {<!-- -->
        unsigned char extrabuff[16];
        memset(extrabuff,16,16);
        for(j = 0; j < 16; j ++ )lpCurOutBuff[j] = extrabuff[j] ^ iv[j];
        Cipher(lpCurOutBuff, lpCurOutBuff, ex_key);
        memcpy(iv, lpCurOutBuff, 16 );
        OutLength + =16;
    }
    return OutLength;
}


/**************************************************** *****
*Function function: AES decryption, mode CBC, data block 128 bits, padding method: pkcs5padding
* Parameters:
* input_buff: array pointer to be decrypted
* InputLen: The byte length of the data to be decrypted
* p_key: pointer to key data, 1~16 bytes in length
* output_buff: encryption result output pointer
*
* Return value: OutLength the encrypted output length
***************************************************** *****/
unsigned long AES128_CBC_Decrypt(unsigned char * input_buff, unsigned long InputLen, unsigned char * p_key, unsigned char * output_buff, unsigned char *iv)
{<!-- -->
    unsigned long OutLength=0;
    long blocknum=InputLen/16;
    long leftnum=InputLen;
    long i,j;
    unsigned char temp[16];

    unsigned char *pCurInBuf=input_buff;
    unsigned char *pCurOutBuf=output_buff;
    int row;
    if(leftnum)
    {<!-- -->return 0;}
    unsigned char ex_key[16*15];
    for(row=0;row<4;row++)
    {<!-- -->
        ex_key[4*row + 0] = *(p_key + 4*row);
        ex_key[4*row + 1] = *(p_key + 4*row + 1);
        ex_key[4*row + 2] = *(p_key + 4*row + 2);
        ex_key[4*row + 3] = *(p_key + 4*row + 3);
    }
    for(row=4;row<44;row++)
    {<!-- -->
        temp[0]=ex_key[4*row-4]; //The previous column of the current column
        temp[1]=ex_key[4*row-3];
        temp[2]=ex_key[4*row-2];
        temp[3]=ex_key[4*row-1];
        if(row%4==0)
        {<!-- -->
            unsigned char exchange_buff=0;
            exchange_buff = temp[0];
            temp[0] = AesSbox[16*(temp[1] >> 4) + (temp[1] & 0x0f)];
            temp[1] = AesSbox[16*(temp[2] >> 4) + (temp[2] & 0x0f)];
            temp[2] = AesSbox[16*(temp[3] >> 4) + (temp[3] & 0x0f)];
            temp[3] = AesSbox[16*(exchange_buff >> 4) + (exchange_buff & 0x0f)];
            temp[0] = temp[0] ^ AesRcon[4*(row/4) + 0];
            temp[1] = temp[1] ^ AesRcon[4*(row/4) + 1];
            temp[2] = temp[2] ^ AesRcon[4*(row/4) + 2];
            temp[3] = temp[3] ^ AesRcon[4*(row/4) + 3];
        }
        ex_key[4*row + 0] = ex_key[4*(row-4) + 0] ^ temp[0] ;
        ex_key[4*row + 1] = ex_key[4*(row-4) + 1] ^ temp[1];
        ex_key[4*row + 2] = ex_key[4*(row-4) + 2] ^ temp[2] ;
        ex_key[4*row + 3] = ex_key[4*(row-4) + 3] ^ temp[3];
    }
    for(i=0;i<blocknum;i++)
    {<!-- -->
        InvCipher(pCurInBuf, pCurOutBuf, ex_key);
        for(j = 0; j < 16; j ++ )
        {<!-- -->
            pCurOutBuf[j] = pCurOutBuf[j] ^ iv[j];
        }
        memcpy( iv, pCurInBuf, 16 );
        if(i == (blocknum-1))
        {<!-- -->
            memset(temp,0,16);
            if(pCurOutBuf[15] != 0x10)
            {<!-- -->
                if(pCurOutBuf[15] < 0x10)
                {<!-- -->
                    OutLength = InputLen - pCurOutBuf[15];
                    memcpy( temp, pCurOutBuf, 16-pCurOutBuf[15] );
                    memcpy( pCurOutBuf, temp, 16 );
                }
                else
                    break;
            }
            else
            {<!-- -->
                OutLength = InputLen - 16;
                memcpy( pCurOutBuf, temp, 16 );
            }
        }
        pCurInBuf + =16;
        pCurOutBuf + =16;
    }
    return OutLength;
}
  • run test code
 int i=0;
    unsigned long outlen;
    unsigned char in[] = {<!-- -->0x32, 0x01, 0x06, 0x29, 0x69, 0x65, 0x06, 0x00, 0x00};
    unsigned char out_data[128] = {<!-- -->0};
    unsigned char in_data[128] = {<!-- -->0};
    unsigned char key[] = {<!-- -->"1234567890abcdef"};
    unsigned char iv[20] = {<!-- -->0};//offset - the default is all '0'
    outlen = AES128_CBC_Encrypt(in, 9, key, out_data, iv); // 9 original text length
    printf("Encrypt_data: ");
    for(i = 0; i < outlen; i ++ )
    {<!-- -->
        if(i ==0)printf("\
");
        printf("x", out_data[i]);
    }
    memset(iv, 0, 20);
    outlen = AES128_CBC_Decrypt(out_data, 16, key, in_data, iv); // 16 encrypted ciphertext length
    printf("\
\
Decrypt_data: ");
    for(i = 0; i < outlen; i ++ )
    {<!-- -->
        if(i % 16==0) printf("\
");
        printf("x", in_data[i]);
    }
    printf("\
\
\
");