基于openssl库实现C语言AES128算法代码

在C语言中使用OpenSSL库实现AES128加密通常涉及以下几个步骤：

#include <stdio.h>
#include <string.h>
#include <openssl/aes.h>
#include <openssl/evp.h>

// AES128 key and IV (16 bytes each)
const unsigned char aes_key[] = "0123456789abcdef01234567";
const unsigned char aes_iv[]   = "fedcba9876543210";

void aes_encrypt(unsigned char *plaintext, int plaintext_len,
                 unsigned char *key, unsigned char *iv) {
    AES_KEY aes;
    AES_set_encrypt_key(key, 128, &aes); // 128 is for AES-128

    unsigned char ciphertext[plaintext_len + AES_BLOCK_SIZE]; // Room for padding
    int ciphertext_len;

    int res = AES_cbc_encrypt(plaintext, ciphertext, plaintext_len,
                              &aes, iv, AES_ENCRYPT);
    if (res == 0) {
        ciphertext_len = plaintext_len; // No padding in this example
    } else {
        // Handle encryption error or padding here
        ciphertext_len = -1;
    }

    // Output encrypted data (or store it securely)
    if (ciphertext_len >= 0) {
        printf("Encrypted:\n");
        for (int i = 0; i < ciphertext_len; i++) {
            printf("%02x ", ciphertext[i]);
        }
        printf("\n");
    }
}

int main() {
    const char* plaintext = "Hello, world!";
    int plaintext_len = strlen(plaintext);

    aes_encrypt((unsigned char*)plaintext, plaintext_len, aes_key, aes_iv);

    return 0;
}

这个例子展示了如何使用AES-128-CBC模式对明文进行加密，但请注意，实际应用中你需要处理加密错误、添加正确的PKCS#7填充等细节。