C语言 AES 加密

加密密码硬编在程序中,有很大的安全隐患

使用C 或C++ 进行接口加密,可以大大降低被破解的可能性.

aes.h

#ifndef _AES_H_
#define _AES_H_

#include <stdint.h>
#include <string.h>
#include <stdlib.h>
#include "base64.h"


// #define the macros below to 1/0 to enable/disable the mode of operation.
//
// CBC enables AES128 encryption in CBC-mode of operation and handles 0-padding.
// ECB enables the basic ECB 16-byte block algorithm. Both can be enabled simultaneously.

// The #ifndef-guard allows it to be configured before #include'ing or at compile time.
#ifndef CBC
  #define CBC 1
#endif

#ifndef ECB
  #define ECB 1
#endif


static const unsigned  char HEX[16]={0x10,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0a,0x0b,0x0c,0x0d,0x0e,0x0f};

#ifdef __cplusplus
extern "C" {
#endif

#if defined(ECB) && ECB

char* AES_ECB_PKCS7_Encrypt(const char *in, const uint8_t *key);
char* AES_ECB_PKCS7_Decrypt(const char *in, const uint8_t *key);

#endif // #if defined(ECB) && ECB


#if defined(CBC) && CBC

char *AES_CBC_PKCS7_Encrypt(const char *in, const uint8_t *key, const uint8_t *iv);
char *AES_CBC_PKCS7_Decrypt(const char *in, const uint8_t *key, const uint8_t *iv);

#endif // #if defined(CBC) && CBC


#ifdef __cplusplus
}
#endif

#endif //_AES_H_

aes.c

/*****************************************************************************/
/* Includes:                                                                 */
/*****************************************************************************/
#include "aes.h"


/*****************************************************************************/
/* Defines:                                                                  */
/*****************************************************************************/
// The number of columns comprising a state in AES. This is a constant in AES. Value=4
#define Nb 4
// aes BLOCK SIZE. Value=16
#define BLOCK_SIZE 16

// jcallan@github points out that declaring Multiply as a function 
// reduces code size considerably with the Keil ARM compiler.
// See this link for more information: https://github.com/kokke/tiny-AES128-C/pull/3
#ifndef MULTIPLY_AS_A_FUNCTION
#define MULTIPLY_AS_A_FUNCTION 0
#endif


/*****************************************************************************/
/* Private variables:                                                        */
/*****************************************************************************/
// state - array holding the intermediate results during decryption.
typedef uint8_t state_t[4][4];
static state_t *state;

// The array that stores the round keys.
static uint8_t RoundKey[240];

// The Key input to the AES Program
static const uint8_t *Key;

// The number of 32 bit words in a key.
static char Nk;//4 for aes 128
// The number of rounds in AES Cipher.
static char Nr;//10 for aes 128
// Key length in bytes [128 bit].
static char KEYLEN;//16 for aes 128

#if defined(CBC) && CBC
// Initial Vector used only for CBC mode
static uint8_t *Iv;
#endif

// The lookup-tables are marked const so they can be placed in read-only storage instead of RAM
// The numbers below can be computed dynamically trading ROM for RAM - 
// This can be useful in (embedded) bootloader applications, where ROM is often limited.
static const uint8_t sbox[256] = {
        //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,
        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 const uint8_t rsbox[256] =
        {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};


// The round constant word array, Rcon[i], contains the values given by 
// x to th e power (i-1) being powers of x (x is denoted as {02}) in the field GF(2^8)
// Note that i starts at 1, not 0).
static const uint8_t Rcon[15] = {
        0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36, 0x6c, 0xd8, 0xab, 0x4d};


/*****************************************************************************/
/* Private functions:                                                        */
/*****************************************************************************/
static uint8_t getSBoxValue(uint8_t num) {
    return sbox[num];
}

static uint8_t getSBoxInvert(uint8_t num) {
    return rsbox[num];
}

// This function produces Nb(Nr+1) round keys. The round keys are used in each round to decrypt the states. 
static void KeyExpansion(void) {
    uint32_t i, j, k;
    uint8_t tempa[4]; // Used for the column/row operations

    Nk = KEYLEN / 4;
    Nr = 6 + Nk;

    // The first round key is the key itself.
    for (i = 0; i < Nk; ++i) {
        RoundKey[(i * 4) + 0] = Key[(i * 4) + 0];
        RoundKey[(i * 4) + 1] = Key[(i * 4) + 1];
        RoundKey[(i * 4) + 2] = Key[(i * 4) + 2];
        RoundKey[(i * 4) + 3] = Key[(i * 4) + 3];
    }

    // All other round keys are found from the previous round keys.
    for (; (i < (Nb * (Nr + 1))); ++i) {
        for (j = 0; j < 4; ++j) {
            tempa[j] = RoundKey[(i - 1) * 4 + j];
        }
        if (i % Nk == 0) {
            // This function rotates the 4 bytes in a word to the left once.
            // [a0,a1,a2,a3] becomes [a1,a2,a3,a0]

            // Function RotWord()
            {
                k = tempa[0];
                tempa[0] = tempa[1];
                tempa[1] = tempa[2];
                tempa[2] = tempa[3];
                tempa[3] = k;
            }

            // SubWord() is a function that takes a four-byte input word and
            // applies the S-box to each of the four bytes to produce an output word.

            // Function Subword()
            {
                tempa[0] = getSBoxValue(tempa[0]);
                tempa[1] = getSBoxValue(tempa[1]);
                tempa[2] = getSBoxValue(tempa[2]);
                tempa[3] = getSBoxValue(tempa[3]);
            }

            tempa[0] = tempa[0] ^ Rcon[i / Nk];
        } else if (Nk > 6 && i % Nk == 4) {
            // Function Subword()
            {
                tempa[0] = getSBoxValue(tempa[0]);
                tempa[1] = getSBoxValue(tempa[1]);
                tempa[2] = getSBoxValue(tempa[2]);
                tempa[3] = getSBoxValue(tempa[3]);
            }
        }
        RoundKey[i * 4 + 0] = RoundKey[(i - Nk) * 4 + 0] ^ tempa[0];
        RoundKey[i * 4 + 1] = RoundKey[(i - Nk) * 4 + 1] ^ tempa[1];
        RoundKey[i * 4 + 2] = RoundKey[(i - Nk) * 4 + 2] ^ tempa[2];
        RoundKey[i * 4 + 3] = RoundKey[(i - Nk) * 4 + 3] ^ tempa[3];
    }
}

// This function adds the round key to state.
// The round key is added to the state by an XOR function.
static void AddRoundKey(uint8_t round) {
    uint8_t i, j;
    for (i = 0; i < 4; ++i) {
        for (j = 0; j < 4; ++j) {
            (*state)[i][j] ^= RoundKey[round * Nb * 4 + i * Nb + j];
        }
    }
}

// The SubBytes Function Substitutes the values in the
// state matrix with values in an S-box.
static void SubBytes(void) {
    uint8_t i, j;
    for (i = 0; i < 4; ++i) {
        for (j = 0; j < 4; ++j) {
            (*state)[j][i] = getSBoxValue((*state)[j][i]);
        }
    }
}

// The ShiftRows() function shifts the rows in the state to the left.
// Each row is shifted with different offset.
// Offset = Row number. So the first row is not shifted.
static void ShiftRows(void) {
    uint8_t temp;

    // Rotate first row 1 columns to left
    temp = (*state)[0][1];
    (*state)[0][1] = (*state)[1][1];
    (*state)[1][1] = (*state)[2][1];
    (*state)[2][1] = (*state)[3][1];
    (*state)[3][1] = temp;

    // Rotate second row 2 columns to left
    temp = (*state)[0][2];
    (*state)[0][2] = (*state)[2][2];
    (*state)[2][2] = temp;

    temp = (*state)[1][2];
    (*state)[1][2] = (*state)[3][2];
    (*state)[3][2] = temp;

    // Rotate third row 3 columns to left
    temp = (*state)[0][3];
    (*state)[0][3] = (*state)[3][3];
    (*state)[3][3] = (*state)[2][3];
    (*state)[2][3] = (*state)[1][3];
    (*state)[1][3] = temp;
}

static uint8_t xtime(uint8_t x) {
    return ((x << 1) ^ (((x >> 7) & 1) * 0x1b));
}

// MixColumns function mixes the columns of the state matrix
static void MixColumns(void) {
    uint8_t i;
    uint8_t Tmp, Tm, t;
    for (i = 0; i < 4; ++i) {
        t = (*state)[i][0];
        Tmp = (*state)[i][0] ^ (*state)[i][1] ^ (*state)[i][2] ^ (*state)[i][3];
        Tm = (*state)[i][0] ^ (*state)[i][1];
        Tm = xtime(Tm);
        (*state)[i][0] ^= Tm ^ Tmp;
        Tm = (*state)[i][1] ^ (*state)[i][2];
        Tm = xtime(Tm);
        (*state)[i][1] ^= Tm ^ Tmp;
        Tm = (*state)[i][2] ^ (*state)[i][3];
        Tm = xtime(Tm);
        (*state)[i][2] ^= Tm ^ Tmp;
        Tm = (*state)[i][3] ^ t;
        Tm = xtime(Tm);
        (*state)[i][3] ^= Tm ^ Tmp;
    }
}

// Multiply is used to multiply numbers in the field GF(2^8)
#if MULTIPLY_AS_A_FUNCTION
static uint8_t Multiply(uint8_t x, uint8_t y)
{
  return (((y & 1) * x) ^
       ((y>>1 & 1) * xtime(x)) ^
       ((y>>2 & 1) * xtime(xtime(x))) ^
       ((y>>3 & 1) * xtime(xtime(xtime(x)))) ^
       ((y>>4 & 1) * xtime(xtime(xtime(xtime(x))))));
  }
#else
#define Multiply(x, y)                                \
      (  ((y & 1) * x) ^                              \
      ((y>>1 & 1) * xtime(x)) ^                       \
      ((y>>2 & 1) * xtime(xtime(x))) ^                \
      ((y>>3 & 1) * xtime(xtime(xtime(x)))) ^         \
      ((y>>4 & 1) * xtime(xtime(xtime(xtime(x))))))   \

#endif

// MixColumns function mixes the columns of the state matrix.
// The method used to multiply may be difficult to understand for the inexperienced.
// Please use the references to gain more information.
static void InvMixColumns(void) {
    int i;
    uint8_t a, b, c, d;
    for (i = 0; i < 4; ++i) {
        a = (*state)[i][0];
        b = (*state)[i][1];
        c = (*state)[i][2];
        d = (*state)[i][3];

        (*state)[i][0] = Multiply(a, 0x0e) ^ Multiply(b, 0x0b) ^ Multiply(c, 0x0d) ^ Multiply(d, 0x09);
        (*state)[i][1] = Multiply(a, 0x09) ^ Multiply(b, 0x0e) ^ Multiply(c, 0x0b) ^ Multiply(d, 0x0d);
        (*state)[i][2] = Multiply(a, 0x0d) ^ Multiply(b, 0x09) ^ Multiply(c, 0x0e) ^ Multiply(d, 0x0b);
        (*state)[i][3] = Multiply(a, 0x0b) ^ Multiply(b, 0x0d) ^ Multiply(c, 0x09) ^ Multiply(d, 0x0e);
    }
}


// The SubBytes Function Substitutes the values in the
// state matrix with values in an S-box.
static void InvSubBytes(void) {
    uint8_t i, j;
    for (i = 0; i < 4; ++i) {
        for (j = 0; j < 4; ++j) {
            (*state)[j][i] = getSBoxInvert((*state)[j][i]);
        }
    }
}

static void InvShiftRows(void) {
    uint8_t temp;

    // Rotate first row 1 columns to right
    temp = (*state)[3][1];
    (*state)[3][1] = (*state)[2][1];
    (*state)[2][1] = (*state)[1][1];
    (*state)[1][1] = (*state)[0][1];
    (*state)[0][1] = temp;

    // Rotate second row 2 columns to right
    temp = (*state)[0][2];
    (*state)[0][2] = (*state)[2][2];
    (*state)[2][2] = temp;

    temp = (*state)[1][2];
    (*state)[1][2] = (*state)[3][2];
    (*state)[3][2] = temp;

    // Rotate third row 3 columns to right
    temp = (*state)[0][3];
    (*state)[0][3] = (*state)[1][3];
    (*state)[1][3] = (*state)[2][3];
    (*state)[2][3] = (*state)[3][3];
    (*state)[3][3] = temp;
}


// Cipher is the main function that encrypts the PlainText.
static void Cipher(void) {
    uint8_t round = 0;

    // Add the First round key to the state before starting the rounds.
    AddRoundKey(0);

    // There will be Nr rounds.
    // The first Nr-1 rounds are identical.
    // These Nr-1 rounds are executed in the loop below.
    for (round = 1; round < Nr; ++round) {
        SubBytes();
        ShiftRows();
        MixColumns();
        AddRoundKey(round);
    }

    // The last round is given below.
    // The MixColumns function is not here in the last round.
    SubBytes();
    ShiftRows();
    AddRoundKey(Nr);
}

static void InvCipher(void) {
    uint8_t round = 0;

    // Add the First round key to the state before starting the rounds.
    AddRoundKey(Nr);

    // There will be Nr rounds.
    // The first Nr-1 rounds are identical.
    // These Nr-1 rounds are executed in the loop below.
    for (round = Nr - 1; round > 0; round--) {
        InvShiftRows();
        InvSubBytes();
        AddRoundKey(round);
        InvMixColumns();
    }

    // The last round is given below.
    // The MixColumns function is not here in the last round.
    InvShiftRows();
    InvSubBytes();
    AddRoundKey(0);
}

static void BlockCopy(uint8_t *output, const uint8_t *input) {
    uint8_t i;
    for (i = 0; i < BLOCK_SIZE; ++i) {
        output[i] = input[i];
    }
}



/*****************************************************************************/
/* Public functions:                                                         */
/*****************************************************************************/

static inline int *findPaddingIndex(uint8_t *str, size_t length) {
    static int result[] = {-1, -1}, i, k;
    for (i = 0; i < length; ++i) {
        char c = str[length - i];
        if ('\0' != c) {
            result[0] = i;
            for (k = 0; k < BLOCK_SIZE; ++k) {
                if (HEX[k] == c) {
                    if (0 == k) {
                        k = BLOCK_SIZE;
                    }
                    result[1] = k;
                    return result;
                }
            }
            return result;
        }
    }
    return 0;
}

static inline uint8_t *getPKCS7PaddingInput(const char *in) {
    int inLength = (int) strlen(in);//输入的长度
    int remainder = inLength % BLOCK_SIZE;
    uint8_t *paddingInput;
    int group = inLength / BLOCK_SIZE;
    int size = BLOCK_SIZE * (group + 1);
    paddingInput = (uint8_t *) malloc(size + 1);

    int dif = size - inLength;
    for (int i = 0; i < size; i++) {
        if (i < inLength) {
            paddingInput[i] = in[i];
        } else {
            if (remainder == 0) {
                //刚好是16倍数,就填充16个16
                paddingInput[i] = HEX[0];
            } else {    //如果不足16位 少多少位就补几个几  如：少4为就补4个4 以此类推
                paddingInput[i] = HEX[dif];
            }
        }
    }
    paddingInput[size] = '\0';
    return paddingInput;
}

static inline void removePKCS7Padding(uint8_t *out, const size_t inputLength) {
    int *result = findPaddingIndex(out, inputLength - 1);
    int offSetIndex = result[0];
    int lastChar = result[1];
    //检查是不是padding的字符,然后去掉
    const size_t noZeroIndex = inputLength - offSetIndex;
    if (lastChar >= 0 && offSetIndex >= 0) {
        int success = 1;
        for (int i = 0; i < lastChar; ++i) {
            size_t index = noZeroIndex - lastChar + i;
            if (!HEX[lastChar] == out[index]) {
                success = 0;
            }
        }
        if (1 == success) {
            out[noZeroIndex - lastChar] = '\0';
            memset(out + noZeroIndex - lastChar + 1, 0, lastChar - 1);
        }
    } else {
        out[noZeroIndex] = '\0';
    }
}

#if defined(ECB) && ECB


static inline void AES_ECB_encrypt(const uint8_t *input, const uint8_t *key, uint8_t *output) {
    // Copy input to output, and work in-memory on output
    BlockCopy(output, input);
    state = (state_t *) output;

    if (Key != key) {
        Key = key;
        KeyExpansion();
    }

    // The next function call encrypts the PlainText with the Key using AES algorithm.
    Cipher();
}

static inline void AES_ECB_decrypt(const uint8_t *input, const uint8_t *key, uint8_t *output) {
    // Copy input to output, and work in-memory on output
    BlockCopy(output, input);
    state = (state_t *) output;

    if (Key != key) {
        Key = key;
        KeyExpansion();
    }

    InvCipher();
}

/**
 * 不定长加密,pkcs7padding，根据密钥长度自动选择128、192、256算法
 */
char *AES_ECB_PKCS7_Encrypt(const char *in, const uint8_t *key) {
    KEYLEN = strlen(key);
    uint8_t *paddingInput = getPKCS7PaddingInput(in);
    int paddingInputLengt = strlen(paddingInput);
    int count = paddingInputLengt / BLOCK_SIZE;
    //开始分段加密
    char *out = (char *) malloc(paddingInputLengt);
    for (int i = 0; i < count; ++i) {
        AES_ECB_encrypt(paddingInput + i * BLOCK_SIZE, key, out + i * BLOCK_SIZE);
    }
    char *base64En = b64_encode(out, paddingInputLengt);
    free(paddingInput);
    free(out);
    return base64En;
}

/**
 * 不定长解密,pkcs7padding，根据密钥长度自动选择128、192、256算法
 */
char *AES_ECB_PKCS7_Decrypt(const char *in, const uint8_t *key) {
    KEYLEN = strlen(key);
    size_t len = strlen(in);
    uint8_t *inputDesBase64 = b64_decode(in, len);
    const size_t inputLength = (len / 4) * 3;
    uint8_t *out = malloc(inputLength);
    memset(out, 0, inputLength);
    size_t count = inputLength / BLOCK_SIZE;
    if (count <= 0) {
        count = 1;
    }
    for (size_t i = 0; i < count; ++i) {
        AES_ECB_decrypt(inputDesBase64 + i * BLOCK_SIZE, key, out + i * BLOCK_SIZE);
    }

    removePKCS7Padding(out, inputLength);
    free(inputDesBase64);
    return (char *) out;
}

#endif // #if defined(ECB) && ECB


#if defined(CBC) && CBC


static void XorWithIv(uint8_t *buf) {
    uint8_t i;
    for (i = 0; i < BLOCK_SIZE; ++i) {
        buf[i] ^= Iv[i];
    }
}

void AES_CBC_encrypt(uint8_t *output, uint8_t *input, uint32_t length, const uint8_t *key, const uint8_t *iv) {
    uintptr_t i;
    uint8_t remainders = length % BLOCK_SIZE; /* Remaining bytes in the last non-full block */

    BlockCopy(output, input);
    state = (state_t *) output;

    // Skip the key expansion if key is passed as 0
    if (0 != key) {
        Key = key;
        KeyExpansion();
    }

    if (iv != 0) {
        Iv = (uint8_t *) iv;
    }

    for (i = 0; i < length; i += BLOCK_SIZE) {
        XorWithIv(input);
        BlockCopy(output, input);
        state = (state_t *) output;
        Cipher();
        Iv = output;
        input += BLOCK_SIZE;
        output += BLOCK_SIZE;
    }

    if (remainders) {
        BlockCopy(output, input);
        memset(output + remainders, 0, BLOCK_SIZE - remainders); /* add 0-padding */
        state = (state_t *) output;
        Cipher();
    }
}

void AES_CBC_decrypt(uint8_t *output, uint8_t *input, uint32_t length, const uint8_t *key, const uint8_t *iv) {
    uintptr_t i;
    uint8_t remainders = length % BLOCK_SIZE; /* Remaining bytes in the last non-full block */

    BlockCopy(output, input);
    state = (state_t *) output;

    // Skip the key expansion if key is passed as 0
    if (0 != key) {
        Key = key;
        KeyExpansion();
    }

    // If iv is passed as 0, we continue to encrypt without re-setting the Iv
    if (iv != 0) {
        Iv = (uint8_t *) iv;
    }

    for (i = 0; i < length; i += BLOCK_SIZE) {
        BlockCopy(output, input);
        state = (state_t *) output;
        InvCipher();
        XorWithIv(output);
        Iv = input;
        input += BLOCK_SIZE;
        output += BLOCK_SIZE;
    }

    if (remainders) {
        BlockCopy(output, input);
        memset(output + remainders, 0, BLOCK_SIZE - remainders); /* add 0-padding */
        state = (state_t *) output;
        InvCipher();
    }
}

/**
 * 不定长加密,pkcs7padding，根据密钥长度自动选择128、192、256算法
 */
char *AES_CBC_PKCS7_Encrypt(const char *in, const uint8_t *key, const uint8_t *iv) {
    KEYLEN = strlen(key);
    uint8_t *paddingInput = getPKCS7PaddingInput(in);
    int paddingInputLengt = strlen(paddingInput);
    char *out = (char *) malloc(paddingInputLengt);
    AES_CBC_encrypt(out, paddingInput, paddingInputLengt, key, iv);
    char *base64En = b64_encode(out, paddingInputLengt);
    free(paddingInput);
    free(out);
    return base64En;
}

/**
 * 不定长解密,pkcs7padding，根据密钥长度自动选择128、192、256算法
 */
char *AES_CBC_PKCS7_Decrypt(const char *in, const uint8_t *key, const uint8_t *iv) {
    KEYLEN = strlen(key);
    size_t len = strlen(in);
    uint8_t *inputDesBase64 = b64_decode(in, len);
    const size_t inputLength = (len / 4) * 3 / BLOCK_SIZE * BLOCK_SIZE;
    uint8_t *out = malloc(inputLength);
    memset(out, 0, inputLength);
    AES_CBC_decrypt(out, inputDesBase64, inputLength, key, iv);

    removePKCS7Padding(out, inputLength);
    free(inputDesBase64);
    return (char *) out;
}

#endif // #if defined(CBC) && CBC

base64.h

/**
 * `b64.h' - b64
 *
 * copyright (c) 2014 joseph werle
 */

#ifndef B64_H
#define B64_H 1

/**
 * Base64 index table.
 */

static const char b64_table[] = {
  'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
  'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
  'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
  'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
  'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
  'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
  'w', 'x', 'y', 'z', '0', '1', '2', '3',
  '4', '5', '6', '7', '8', '9', '+', '/'
};

#ifdef __cplusplus
extern "C" {
#endif

/**
 * Encode `unsigned char *' source with `size_t' size.
 * Returns a `char *' base64 encoded string.
 */

char *
b64_encode (const unsigned char *, size_t);

/**
 * Dencode `char *' source with `size_t' size.
 * Returns a `unsigned char *' base64 decoded string.
 */
unsigned char *
b64_decode (const char *, size_t);

/**
 * Dencode `char *' source with `size_t' size.
 * Returns a `unsigned char *' base64 decoded string + size of decoded string.
 */
unsigned char *
b64_decode_ex (const char *, size_t, size_t *);

#ifdef __cplusplus
}
#endif

#endif

base64.c

/**
 * `encode.c' - b64
 *
 * copyright (c) 2014 joseph werle
 */

#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include "base64.h"



char *
b64_encode (const unsigned char *src, size_t len) {
  int i = 0;
  int j = 0;
  char *enc = NULL;
  size_t size = 0;
  unsigned char buf[4];
  unsigned char tmp[3];

  // alloc
  enc = (char *) malloc(0);
  if (NULL == enc) { return NULL; }

  // parse until end of source
  while (len--) {
    // read up to 3 bytes at a time into `tmp'
    tmp[i++] = *(src++);

    // if 3 bytes read then encode into `buf'
    if (3 == i) {
      buf[0] = (tmp[0] & 0xfc) >> 2;
      buf[1] = ((tmp[0] & 0x03) << 4) + ((tmp[1] & 0xf0) >> 4);
      buf[2] = ((tmp[1] & 0x0f) << 2) + ((tmp[2] & 0xc0) >> 6);
      buf[3] = tmp[2] & 0x3f;

      // allocate 4 new byts for `enc` and
      // then translate each encoded buffer
      // part by index from the base 64 index table
      // into `enc' unsigned char array
      enc = (char *) realloc(enc, size + 4);
      for (i = 0; i < 4; ++i) {
        enc[size++] = b64_table[buf[i]];
      }

      // reset index
      i = 0;
    }
  }

  // remainder
  if (i > 0) {
    // fill `tmp' with `\0' at most 3 times
    for (j = i; j < 3; ++j) {
      tmp[j] = '\0';
    }

    // perform same codec as above
    buf[0] = (tmp[0] & 0xfc) >> 2;
    buf[1] = ((tmp[0] & 0x03) << 4) + ((tmp[1] & 0xf0) >> 4);
    buf[2] = ((tmp[1] & 0x0f) << 2) + ((tmp[2] & 0xc0) >> 6);
    buf[3] = tmp[2] & 0x3f;

    // perform same write to `enc` with new allocation
    for (j = 0; (j < i + 1); ++j) {
      enc = (char *) realloc(enc, size + 1);
      enc[size++] = b64_table[buf[j]];
    }

    // while there is still a remainder
    // append `=' to `enc'
    while ((i++ < 3)) {
      enc = (char *) realloc(enc, size + 1);
      enc[size++] = '=';
    }
  }

  // Make sure we have enough space to add '\0' character at end.
  enc = (char *) realloc(enc, size + 1);
  enc[size] = '\0';

  return enc;
}


unsigned char *
b64_decode(const char *src, size_t len) {
  return b64_decode_ex(src, len, NULL);
}

unsigned char *
b64_decode_ex(const char *src, size_t len, size_t *decsize) {
  int i = 0;
  int j = 0;
  int l = 0;
  size_t size = 0;
  unsigned char *dec = NULL;
  unsigned char buf[3];
  unsigned char tmp[4];

  // alloc
  dec = (unsigned char *) malloc(0);
  if (NULL == dec) { return NULL; }

  // parse until end of source
  while (len--) {
    // break if char is `=' or not base64 char
    if ('=' == src[j]) { break; }
    if (!(isalnum(src[j]) || '+' == src[j] || '/' == src[j])) { break; }

    // read up to 4 bytes at a time into `tmp'
    tmp[i++] = src[j++];

    // if 4 bytes read then decode into `buf'
    if (4 == i) {
      // translate values in `tmp' from table
      for (i = 0; i < 4; ++i) {
        // find translation char in `b64_table'
        for (l = 0; l < 64; ++l) {
          if (tmp[i] == b64_table[l]) {
            tmp[i] = l;
            break;
          }
        }
      }

      // decode
      buf[0] = (tmp[0] << 2) + ((tmp[1] & 0x30) >> 4);
      buf[1] = ((tmp[1] & 0xf) << 4) + ((tmp[2] & 0x3c) >> 2);
      buf[2] = ((tmp[2] & 0x3) << 6) + tmp[3];

      // write decoded buffer to `dec'
      dec = (unsigned char *) realloc(dec, size + 3);
      for (i = 0; i < 3; ++i) {
        dec[size++] = buf[i];
      }

      // reset
      i = 0;
    }
  }

  // remainder
  if (i > 0) {
    // fill `tmp' with `\0' at most 4 times
    for (j = i; j < 4; ++j) {
      tmp[j] = '\0';
    }

    // translate remainder
    for (j = 0; j < 4; ++j) {
      // find translation char in `b64_table'
      for (l = 0; l < 64; ++l) {
        if (tmp[j] == b64_table[l]) {
          tmp[j] = l;
          break;
        }
      }
    }

    // decode remainder
    buf[0] = (tmp[0] << 2) + ((tmp[1] & 0x30) >> 4);
    buf[1] = ((tmp[1] & 0xf) << 4) + ((tmp[2] & 0x3c) >> 2);
    buf[2] = ((tmp[2] & 0x3) << 6) + tmp[3];

    // write remainer decoded buffer to `dec'
    dec = (unsigned char *) realloc(dec, size + (i - 1));
    for (j = 0; (j < i - 1); ++j) {
      dec[size++] = buf[j];
    }
  }

  // Make sure we have enough space to add '\0' character at end.
  dec = (unsigned char *) realloc(dec, size + 1);
  dec[size] = '\0';

  // Return back the size of decoded string if demanded.
  if (decsize != NULL) *decsize = size;

  return dec;
}