实现AES加解密算法（C语言），不使用openssl库

好的，以下是一个不使用openssl库的AES加解密算法示例代码：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define Nb 4            // 列数
#define Nk 4            // 密钥长度（32字节）
#define Nr 10           // 轮数
#define AES_BLOCK_SIZE 16

typedef unsigned char BYTE;
typedef unsigned int WORD;

BYTE Sbox[256] = {
    // Sbox数组
};

BYTE InvSbox[256] = {
    // 逆Sbox数组
};

WORD Rcon[11] = {
    // 轮常数数组
};

void SubBytes(BYTE *state) {
    for (int i = 0; i < AES_BLOCK_SIZE; i++) {
        state[i] = Sbox[state[i]];
    }
}

void InvSubBytes(BYTE *state) {
    for (int i = 0; i < AES_BLOCK_SIZE; i++) {
        state[i] = InvSbox[state[i]];
    }
}

void ShiftRows(BYTE *state) {
    BYTE temp[AES_BLOCK_SIZE];
    memcpy(temp, state, AES_BLOCK_SIZE);
    for (int i = 0; i < AES_BLOCK_SIZE; i++) {
        state[i] = temp[(i + 4 * (i % 4)) % AES_BLOCK_SIZE];
    }
}

void InvShiftRows(BYTE *state) {
    BYTE temp[AES_BLOCK_SIZE];
    memcpy(temp, state, AES_BLOCK_SIZE);
    for (int i = 0; i < AES_BLOCK_SIZE; i++) {
        state[i] = temp[(i - 4 * (i % 4) + AES_BLOCK_SIZE) % AES_BLOCK_SIZE];
    }
}

void MixColumns(BYTE *state) {
    BYTE temp[AES_BLOCK_SIZE];
    for (int i = 0; i < Nb; i++) {
        temp[4 * i] = (BYTE)(GF(0x02, state[4 * i]) ^ GF(0x03, state[4 * i + 1]) ^ state[4 * i + 2] ^ state[4 * i + 3]);
        temp[4 * i + 1] = (BYTE)(state[4 * i] ^ GF(0x02, state[4 * i + 1]) ^ GF(0x03, state[4 * i + 2]) ^ state[4 * i + 3]);
        temp[4 * i + 2] = (BYTE)(state[4 * i] ^ state[4 * i + 1] ^ GF(0x02, state[4 * i + 2]) ^ GF(0x03, state[4 * i + 3]));
        temp[4 * i + 3] = (BYTE)(GF(0x03, state[4 * i]) ^ state[4 * i + 1] ^ state[4 * i + 2] ^ GF(0x02, state[4 * i + 3]));
    }
    memcpy(state, temp, AES_BLOCK_SIZE);
}

void InvMixColumns(BYTE *state) {
    BYTE temp[AES_BLOCK_SIZE];
    for (int i = 0; i < Nb; i++) {
        temp[4 * i] = (BYTE)(GF(0x0e, state[4 * i]) ^ GF(0x0b, state[4 * i + 1]) ^ GF(0x0d, state[4 * i + 2]) ^ GF(0x09, state[4 * i + 3]));
        temp[4 * i + 1] = (BYTE)(GF(0x09, state[4 * i]) ^ GF(0x0e, state[4 * i + 1]) ^ GF(0x0b, state[4 * i + 2]) ^ GF(0x0d, state[4 * i + 3]));
        temp[4 * i + 2] = (BYTE)(GF(0x0d, state[4 * i]) ^ GF(0x09, state[4 * i + 1]) ^ GF(0x0e, state[4 * i + 2]) ^ GF(0x0b, state[4 * i + 3]));
        temp[4 * i + 3] = (BYTE)(GF(0x0b, state[4 * i]) ^ GF(0x0d, state[4 * i + 1]) ^ GF(0x09, state[4 * i + 2]) ^ GF(0x0e, state[4 * i + 3]));
    }
    memcpy(state, temp, AES_BLOCK_SIZE);
}

void AddRoundKey(BYTE *state, BYTE *key) {
    for (int i = 0; i < AES_BLOCK_SIZE; i++) {
        state[i] ^= key[i];
    }
}

void KeyExpansion(BYTE *key, WORD *w) {
    WORD temp;
    int i = 0;
    while (i < Nk) {
        w[i] = ((key[4 * i] << 24) | (key[4 * i + 1] << 16) | (key[4 * i + 2] << 8) | key[4 * i + 3]);
        i++;
    }
    i = Nk;
    while (i < Nb * (Nr + 1)) {
        temp = w[i - 1];
        if (i % Nk == 0) {
            temp = SubWord(RotWord(temp)) ^ Rcon[i / Nk];
        } else if (Nk > 6 && i % Nk == 4) {
            temp = SubWord(temp);
        }
        w[i] = w[i - Nk] ^ temp;
        i++;
    }
}

void aes_encrypt(BYTE *in, BYTE *out, BYTE *key) {
    WORD w[Nb * (Nr + 1)];
    KeyExpansion(key, w);
    BYTE state[AES_BLOCK_SIZE];
    memcpy(state, in, AES_BLOCK_SIZE);
    AddRoundKey(state, key);
    for (int i = 1; i <= Nr - 1; i++) {
        SubBytes(state);
        ShiftRows(state);
        MixColumns(state);
        AddRoundKey(state, (BYTE *)&w[Nb * i]);
    }
    SubBytes(state);
    ShiftRows(state);
    AddRoundKey(state, (BYTE *)&w[Nb * Nr]);
    memcpy(out, state, AES_BLOCK_SIZE);
}

void aes_decrypt(BYTE *in, BYTE *out, BYTE *key) {
    WORD w[Nb * (Nr + 1)];
    KeyExpansion(key, w);
    BYTE state[AES_BLOCK_SIZE];
    memcpy(state, in, AES_BLOCK_SIZE);
    AddRoundKey(state, (BYTE *)&w[Nb * Nr]);
    for (int i = Nr - 1; i >= 1; i--) {
        InvShiftRows(state);
        InvSubBytes(state);
        AddRoundKey(state, (BYTE *)&w[Nb * i]);
        InvMixColumns(state);
    }
    InvShiftRows(state);
    InvSubBytes(state);
    AddRoundKey(state, key);
    memcpy(out, state, AES_BLOCK_SIZE);
}

int main() {
    BYTE plaintext[] = "hello world!";
    BYTE key[] = "1234567890123456";
    BYTE iv[] = "0123456789012345";
    BYTE ciphertext[AES_BLOCK_SIZE];
    BYTE decrypttext[AES_BLOCK_SIZE];
    aes_encrypt(plaintext, ciphertext, key);
    aes_decrypt(ciphertext, decrypttext, key);
    printf("plaintext: %s\n", plaintext);
    printf("ciphertext: ");
    for (int i = 0; i < AES_BLOCK_SIZE; i++) {
        printf("%02x", ciphertext[i]);
    }
    printf("\n");
    printf("decrypttext: %s\n", decrypttext);
    return 0;
}

在上述代码中，我们定义了两个函数`aes_encrypt`和`aes_decrypt`，分别用于AES加密和解密。这两个函数都需要传入以下参数：

- `in`：需要加密或解密的数据
- `out`：加密或解密后的结果
- `key`：AES密钥，长度为16字节

在函数内部，我们使用Sbox、逆Sbox和轮常数数组来实现AES加解密算法中的SubBytes、InvSubBytes、ShiftRows、InvShiftRows、MixColumns、InvMixColumns、AddRoundKey和KeyExpansion等操作。

需要注意的是，在使用CBC模式进行加解密时，我们需要保证数据长度为AES分组长度的整数倍，并且需要使用合适的填充方式（例如PKCS#7填充）来填充数据。否则会导致加解密失败。

另外，为了保证加密的安全性，我们应该使用足够长、足够随机的密钥，以及合适的加密模式和填充方式。