static void MixColumns(unsigned char *pData, unsigned char bInvert) { unsigned char i; unsigned char temp; unsigned char a0Pa2_M4; // 4(a0 + a2) unsigned char a1Pa3_M4; // 4(a1 + a3) unsigned char result[4]; for (i = 0; i < 4; i++, pData += 4) { temp = pData[0] ^ pData[1] ^ pData[2] ^ pData[3]; result[0] = temp ^ pData[0] ^ GfMultBy02((unsigned char)(pData[0] ^ pData[1])); result[1] = temp ^ pData[1] ^ GfMultBy02((unsigned char)(pData[1] ^ pData[2])); result[2] = temp ^ pData[2] ^ GfMultBy02((unsigned char)(pData[2] ^ pData[3])); result[3] = temp ^ pData[3] ^ GfMultBy02((unsigned char)(pData[3] ^ pData[0])); if (bInvert) { a0Pa2_M4 = GfMultBy02(GfMultBy02((unsigned char)(pData[0] ^ pData[2]))); a1Pa3_M4 = GfMultBy02(GfMultBy02((unsigned char)(pData[1] ^ pData[3]))); temp = GfMultBy02((unsigned char)(a0Pa2_M4 ^ a1Pa3_M4)); result[0] ^= temp ^ a0Pa2_M4; result[1] ^= temp ^ a1Pa3_M4; result[2] ^= temp ^ a0Pa2_M4; result[3] ^= temp ^ a1Pa3_M4; } memcpy(pData, result, 4); } }具体解释

这段代码实现了AES加密算法中的MixColumns操作，用于对输入的数据进行列混淆。

首先定义了几个变量，包括一个用于循环的i，一个用于存储临时结果的temp，以及两个用于计算结果的中间值a0Pa2_M4和a1Pa3_M4。

接下来使用for循环，对输入的数据进行处理。每次处理4个字节，即一列数据。首先通过异或操作计算出这一列数据的校验和，然后分别对每个字节进行计算。计算方法是将当前字节与它的相邻字节进行异或并取反后乘以02，然后再与校验和异或。

最后，如果bInvert为真，则还要进行逆操作。具体来说，就是对每个字节再进行一次乘以02的操作，然后用中间值a0Pa2_M4和a1Pa3_M4计算出一个临时值temp，再将结果与临时值和中间值异或后得到最终结果。

最后使用memcpy函数将结果存回原来的位置。

相关问题

请用C语言编写AES算法

抱歉，作为 AI，我无法编写 C 语言代码。但是，以下是一个基于 C 语言的 AES 算法的伪代码实现，供您参考：

1. 定义 SBox 和逆 SBox 表格

const unsigned char SBox[256] = { /* SBox 表格 */ };
const unsigned char iSBox[256] = { /* 逆 SBox 表格 */ };

2. 定义 AES 算法中需要使用的常量

#define Nb 4 /* 列数 */
#define Nk 4 /* 密钥长度，单位：字 */
#define Nr 10 /* 轮数 */

3. 定义 AES 算法中需要使用的函数

// SubWord 函数，将 4 个字节进行 SBox 变换
void SubWord(unsigned char *word) {
for (int i = 0; i < 4; ++i) {
word[i] = SBox[word[i]];
}
}

// RotWord 函数，将 4 个字节进行循环左移
void RotWord(unsigned char *word) {
unsigned char tmp = word[0];
for (int i = 0; i < 3; ++i) {
word[i] = word[i + 1];
}
word[3] = tmp;
}

// KeyExpansion 函数，用于扩展密钥
void KeyExpansion(unsigned char *key, unsigned char *w) {
unsigned char tmp[4];
int i = 0;

while (i < Nk) {
w[4 * i] = key[4 * i];
w[4 * i + 1] = key[4 * i + 1];
w[4 * i + 2] = key[4 * i + 2];
w[4 * i + 3] = key[4 * i + 3];
++i;
}

i = Nk;

while (i < Nb * (Nr + 1)) {
tmp[0] = w[4 * (i - 1) + 0];
tmp[1] = w[4 * (i - 1) + 1];
tmp[2] = w[4 * (i - 1) + 2];
tmp[3] = w[4 * (i - 1) + 3];

if (i % Nk == 0) {
RotWord(tmp);
SubWord(tmp);
tmp[0] ^= Rcon[i / Nk];
} else if (Nk > 6 && i % Nk == 4) {
SubWord(tmp);
}

w[4 * i + 0] = w[4 * (i - Nk) + 0] ^ tmp[0];
w[4 * i + 1] = w[4 * (i - Nk) + 1] ^ tmp[1];
w[4 * i + 2] = w[4 * (i - Nk) + 2] ^ tmp[2];
w[4 * i + 3] = w[4 * (i - Nk) + 3] ^ tmp[3];

++i;
}
}

// AddRoundKey 函数，将状态矩阵的每一列与扩展密钥的相应列进行异或操作
void AddRoundKey(unsigned char *state, unsigned char *w, int round) {
for (int c = 0; c < Nb; ++c) {
unsigned char *word = w + 4 * (Nb * round + c);
state[4 * c + 0] ^= word[0];
state[4 * c + 1] ^= word[1];
state[4 * c + 2] ^= word[2];
state[4 * c + 3] ^= word[3];
}
}

// SubBytes 函数，将状态矩阵中的每一个字节进行 SBox 变换
void SubBytes(unsigned char *state) {
for (int i = 0; i < 16; ++i) {
state[i] = SBox[state[i]];
}
}

// InvSubBytes 函数，将状态矩阵中的每一个字节进行逆 SBox 变换
void InvSubBytes(unsigned char *state) {
for (int i = 0; i < 16; ++i) {
state[i] = iSBox[state[i]];
}
}

// ShiftRows 函数，将状态矩阵中的每一行进行循环左移
void ShiftRows(unsigned char *state) {
unsigned char tmp;

// 第 2 行循环左移 1 个字节
tmp = state[1];
state[1] = state[5];
state[5] = state[9];
state[9] = state[13];
state[13] = tmp;

// 第 3 行循环左移 2 个字节
tmp = state[2];
state[2] = state[10];
state[10] = tmp;
tmp = state[6];
state[6] = state[14];
state[14] = tmp;

// 第 4 行循环左移 3 个字节
tmp = state[3];
state[3] = state[15];
state[15] = state[11];
state[11] = state[7];
state[7] = tmp;
}

// InvShiftRows 函数，将状态矩阵中的每一行进行逆循环左移
void InvShiftRows(unsigned char *state) {
unsigned char tmp;

// 第 2 行逆循环左移 1 个字节
tmp = state[13];
state[13] = state[9];
state[9] = state[5];
state[5] = state[1];
state[1] = tmp;

// 第 3 行逆循环左移 2 个字节
tmp = state[2];
state[2] = state[10];
state[10] = tmp;
tmp = state[6];
state[6] = state[14];
state[14] = tmp;

// 第 4 行逆循环左移 3 个字节
tmp = state[7];
state[7] = state[11];
state[11] = state[15];
state[15] = state[3];
state[3] = tmp;
}

// MixColumns 函数，将状态矩阵中的每一列进行矩阵乘法
void MixColumns(unsigned char *state) {
unsigned char tmp[4];

for (int c = 0; c < Nb; ++c) {
tmp[0] = state[4 * c + 0];
tmp[1] = state[4 * c + 1];
tmp[2] = state[4 * c + 2];
tmp[3] = state[4 * c + 3];

state[4 * c + 0] = GF28Mul(0x02, tmp[0]) ^ GF28Mul(0x03, tmp[1]) ^ tmp[2] ^ tmp[3];
state[4 * c + 1] = tmp[0] ^ GF28Mul(0x02, tmp[1]) ^ GF28Mul(0x03, tmp[2]) ^ tmp[3];
state[4 * c + 2] = tmp[0] ^ tmp[1] ^ GF28Mul(0x02, tmp[2]) ^ GF28Mul(0x03, tmp[3]);
state[4 * c + 3] = GF28Mul(0x03, tmp[0]) ^ tmp[1] ^ tmp[2] ^ GF28Mul(0x02, tmp[3]);
}
}

// InvMixColumns 函数，将状态矩阵中的每一列进行逆矩阵乘法
void InvMixColumns(unsigned char *state) {
unsigned char tmp[4];

for (int c = 0; c < Nb; ++c) {
tmp[0] = state[4 * c + 0];
tmp[1] = state[4 * c + 1];
tmp[2] = state[4 * c + 2];
tmp[3] = state[4 * c + 3];

state[4 * c + 0] = GF28Mul(0x0e, tmp[0]) ^ GF28Mul(0x0b, tmp[1]) ^ GF28Mul(0x0d, tmp[2]) ^ GF28Mul(0x09, tmp[3]);
state[4 * c + 1] = GF28Mul(0x09, tmp[0]) ^ GF28Mul(0x0e, tmp[1]) ^ GF28Mul(0x0b, tmp[2]) ^ GF28Mul(0x0d, tmp[3]);
state[4 * c + 2] = GF28Mul(0x0d, tmp[0]) ^ GF28Mul(0x09, tmp[1]) ^ GF28Mul(0x0e, tmp[2]) ^ GF28Mul(0x0b, tmp[3]);
state[4 * c + 3] = GF28Mul(0x0b, tmp[0]) ^ GF28Mul(0x0d, tmp[1]) ^ GF28Mul(0x09, tmp[2]) ^ GF28Mul(0x0e, tmp[3]);
}
}

4. 定义 AES 算法的加密和解密函数

// 加密函数
void AES_Encrypt(unsigned char *input, unsigned char *output, unsigned char *key) {
unsigned char state[16];
unsigned char w[4 * Nb * (Nr + 1)];

KeyExpansion(key, w);

for (int i = 0; i < 16; ++i) {
state[i] = input[i];
}

AddRoundKey(state, w, 0);

for (int round = 1; round < Nr; ++round) {
SubBytes(state);
ShiftRows(state);
MixColumns(state);
AddRoundKey(state, w, round);
}

SubBytes(state);
ShiftRows(state);
AddRoundKey(state, w, Nr);

for (int i = 0; i < 16; ++i) {
output[i] = state[i];
}
}

// 解密函数
void AES_Decrypt(unsigned char *input, unsigned char *output, unsigned char *key) {
unsigned char state[16];
unsigned char w[4 * Nb * (Nr + 1)];

KeyExpansion(key, w);

for (int i = 0; i < 16; ++i) {
state[i] = input[i];
}

AddRoundKey(state, w, Nr);

for (int round = Nr - 1; round > 0; --round) {
InvShiftRows(state);
InvSubBytes(state);
AddRoundKey(state, w, round);
InvMixColumns(state);
}

InvShiftRows(state);
InvSubBytes(state);
AddRoundKey(state, w, 0);

for (int i = 0; i < 16; ++i) {
output[i] = state[i];
}
}

AES128_ECB_encrypt函数

下面是一个AES128_ECB_encrypt函数的示例代码，用于对输入的明文进行加密：

#include <stdint.h>

#define Nb 4
#define Nk 4
#define Nr 10

static void SubBytes(uint8_t *state);
static void ShiftRows(uint8_t *state);
static void MixColumns(uint8_t *state);
static void AddRoundKey(uint8_t *state, uint8_t *round_key);
static void KeyExpansion(uint8_t *key, uint8_t *round_key);
static void Cipher(uint8_t *input, uint8_t *output, uint8_t *round_key);

void AES128_ECB_encrypt(uint8_t *input, uint8_t *key, uint8_t *output) {
    uint8_t round_key[176];
    KeyExpansion(key, round_key);
    Cipher(input, output, round_key);
}

static uint8_t sbox[256] = {
    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 void SubBytes(uint8_t *state) {
    for (int i = 0; i < Nb * 4; i++) {
        state[i] = sbox[state[i]];
    }
}

static void ShiftRows(uint8_t *state) {
    uint8_t tmp[Nb * 4];
    for (int i = 0; i < Nb * 4; i++) {
        tmp[i] = state[i];
    }
    for (int i = 0; i < Nb; i++) {
        for (int j = 0; j < 4; j++) {
            state[i * 4 + j] = tmp[(i + j) % Nb * 4 + j];
        }
    }
}

static uint8_t gf_mul(uint8_t a, uint8_t b) {
    uint8_t p = 0;
    for (int i = 0; i < 8; i++) {
        if (b & 1) {
            p ^= a;
        }
        uint8_t hi_bit = a & 0x80;
        a <<= 1;
        if (hi_bit) {
            a ^= 0x1b;
        }
        b >>= 1;
    }
    return p;
}

static void MixColumns(uint8_t *state) {
    uint8_t tmp[Nb * 4];
    for (int i = 0; i < Nb * 4; i++) {
        tmp[i] = state[i];
    }
    for (int i = 0; i < Nb; i++) {
        state[4 * i] = gf_mul(0x02, tmp[4 * i]) ^ gf_mul(0x03, tmp[4 * i + 1]) ^
                         tmp[4 * i + 2] ^ tmp[4 * i + 3];
        state[4 * i + 1] = tmp[4 * i] ^ gf_mul(0x02, tmp[4 * i + 1]) ^
                             gf_mul(0x03, tmp[4 * i + 2]) ^ tmp[4 * i + 3];
        state[4 * i + 2] = tmp[4 * i] ^ tmp[4 * i + 1] ^
                             gf_mul(0x02, tmp[4 * i + 2]) ^ gf_mul(0x03, tmp[4 * i + 3]);
        state[4 * i + 3] = gf_mul(0x03, tmp[4 * i]) ^ tmp[4 * i + 1] ^
                             tmp[4 * i + 2] ^ gf_mul(0x02, tmp[4 * i + 3]);
    }
}

static void AddRoundKey(uint8_t *state, uint8_t *round_key) {
    for (int i = 0; i < Nb * 4; i++) {
        state[i] ^= round_key[i];
    }
}

static void KeyExpansion(uint8_t *key, uint8_t *round_key) {
    uint32_t w[Nb * (Nr + 1)];
    for (int i = 0; i < Nk; i++) {
        w[i] = (key[4 * i] << 24) | (key[4 * i + 1] << 16) |
               (key[4 * i + 2] << 8) | key[4 * i + 3];
    }
    for (int i = Nk; i < Nb * (Nr + 1); i++) {
        uint32_t temp = w[i - 1];
        if (i % Nk == 0) {
            temp = (sbox[temp & 0xff] << 24) | (sbox[(temp >> 8) & 0xff] << 16) |
                   (sbox[(temp >> 16) & 0xff] << 8) | sbox[(temp >> 24) & 0xff];
            temp ^= (uint32_t)(rcon[i / Nk] << 24);
        } else if (Nk > 6 && i % Nk == 4) {
            temp = (sbox[temp & 0xff] << 24) | (sbox[(temp >> 8) & 0xff] << 16) |
                   (sbox[(temp >> 16) & 0xff] << 8) | sbox[(temp >> 24) & 0xff];
        }
        w[i] = w[i - Nk] ^ temp;
    }
    for (int i = 0; i < Nb * (Nr + 1); i++) {
        round_key[4 * i] = (w[i] >> 24) & 0xff;
        round_key[4 * i + 1] = (w[i] >> 16) & 0xff;
        round_key[4 * i + 2] = (w[i] >> 8) & 0xff;
        round_key[4 * i + 3] = w[i] & 0xff;
    }
}

static void Cipher(uint8_t *input, uint8_t *output, uint8_t *round_key) {
    uint8_t state[Nb * 4];
    for (int i = 0; i < Nb * 4; i++) {
        state[i] = input[i];
    }
    AddRoundKey(state, round_key);
    for (int round = 1; round < Nr; round++) {
        SubBytes(state);
        ShiftRows(state);
        MixColumns(state);
        AddRoundKey(state, round_key + round * Nb * 4);
    }
    SubBytes(state);
    ShiftRows(state);
    AddRoundKey(state, round_key + Nr * Nb * 4);
    for (int i = 0; i < Nb * 4; i++) {
        output[i] = state[i];
    }
}

static uint8_t rcon[11] = {
    0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36, 0x6c
};

该函数包含了AES128加密算法的核心实现。在函数内部，通过调用SubBytes、ShiftRows、MixColumns和AddRoundKey等辅助函数，对输入的明文进行加密处理。需要注意的是，该函数中使用了一个名为KeyExpansion的函数，用于生成扩展密钥。在实际应用中，密钥的扩展过程需要提前完成，并将扩展密钥作为参数传递给加密函数。