c语言实现ECC加密算法

C语言实现ECC加密算法需要使用一些数学库来完成椭圆曲线运算，比较复杂。这里提供一个基于OpenSSL库的示例代码，用于生成密钥对和加密解密数据：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <openssl/evp.h>
#include <openssl/ec.h>
#include <openssl/ecdsa.h>
#include <openssl/bn.h>
#include <openssl/rand.h>

#define BUFSIZE 1024

int main() {
    int rc = 0;
    int curve_nid = NID_secp256k1;
    char *message = "Hello, world!";
    size_t message_len = strlen(message);

    // 初始化OpenSSL库
    OpenSSL_add_all_algorithms();
    RAND_poll();

    // 生成密钥对
    EC_KEY *eckey = NULL;
    eckey = EC_KEY_new_by_curve_name(curve_nid);
    if (!eckey) {
        printf("Error: EC_KEY_new_by_curve_name\n");
        return -1;
    }
    if (!EC_KEY_generate_key(eckey)) {
        printf("Error: EC_KEY_generate_key\n");
        return -1;
    }

    // 显示公钥和私钥
    EC_POINT *pub_key = NULL;
    pub_key = EC_KEY_get0_public_key(eckey);
    BIGNUM *priv_key = NULL;
    priv_key = EC_KEY_get0_private_key(eckey);

    char *priv_key_hex = NULL;
    priv_key_hex = BN_bn2hex(priv_key);
    printf("Private Key: %s\n", priv_key_hex);

    char *pub_key_hex = NULL;
    pub_key_hex = EC_POINT_point2hex(EC_KEY_get0_group(eckey), pub_key, POINT_CONVERSION_COMPRESSED, NULL);
    printf("Public Key: %s\n", pub_key_hex);

    // 加密解密数据
    EVP_PKEY *privkey = EVP_PKEY_new();
    if (!privkey) {
        printf("Error: EVP_PKEY_new\n");
        return -1;
    }
    if (!EVP_PKEY_set1_EC_KEY(privkey, eckey)) {
        printf("Error: EVP_PKEY_set1_EC_KEY\n");
        return -1;
    }

    EVP_PKEY *pubkey = EVP_PKEY_new();
    if (!pubkey) {
        printf("Error: EVP_PKEY_new\n");
        return -1;
    }
    if (!EVP_PKEY_set1_EC_KEY(pubkey, eckey)) {
        printf("Error: EVP_PKEY_set1_EC_KEY\n");
        return -1;
    }

    EVP_CIPHER_CTX *ctx = EVP_CIPHER_CTX_new();
    if (!ctx) {
        printf("Error: EVP_CIPHER_CTX_new\n");
        return -1;
    }

    unsigned char iv[BUFSIZE] = {0};
    unsigned char out[BUFSIZE] = {0};
    int outlen;
    if (!EVP_EncryptInit_ex(ctx, EVP_aes_128_cbc(), NULL, NULL, iv)) {
        printf("Error: EVP_EncryptInit_ex\n");
        return -1;
    }
    if (!EVP_EncryptUpdate(ctx, out, &outlen, (unsigned char *)message, message_len)) {
        printf("Error: EVP_EncryptUpdate\n");
        return -1;
    }
    if (!EVP_EncryptFinal_ex(ctx, out + outlen, &outlen)) {
        printf("Error: EVP_EncryptFinal_ex\n");
        return -1;
    }

    unsigned char *encrypted_data = NULL;
    size_t encrypted_data_len = outlen + message_len;
    encrypted_data = (unsigned char *)malloc(encrypted_data_len);
    if (!encrypted_data) {
        printf("Error: malloc\n");
        return -1;
    }
    memcpy(encrypted_data, out, outlen);
    memcpy(encrypted_data + outlen, message, message_len);

    unsigned char decrypted_data[BUFSIZE] = {0};
    int decrypted_data_len = 0;
    if (!EVP_DecryptInit_ex(ctx, EVP_aes_128_cbc(), NULL, NULL, iv)) {
        printf("Error: EVP_DecryptInit_ex\n");
        return -1;
    }
    if (!EVP_DecryptUpdate(ctx, decrypted_data, &decrypted_data_len, encrypted_data, encrypted_data_len)) {
        printf("Error: EVP_DecryptUpdate\n");
        return -1;
    }
    if (!EVP_DecryptFinal_ex(ctx, decrypted_data + decrypted_data_len, &decrypted_data_len)) {
        printf("Error: EVP_DecryptFinal_ex\n");
        return -1;
    }

    // 显示加密和解密结果
    printf("Plain Text: %s\n", message);
    printf("Cipher Text: ");
    for (int i = 0; i < encrypted_data_len; i++) {
        printf("%02x", encrypted_data[i]);
    }
    printf("\n");
    printf("Decrypted Text: %s\n", decrypted_data);

    // 释放资源
    free(encrypted_data);
    EC_KEY_free(eckey);
    EVP_PKEY_free(privkey);
    EVP_PKEY_free(pubkey);
    EVP_CIPHER_CTX_free(ctx);
    OPENSSL_cleanup();

    return 0;
}

需要使用OpenSSL库来实现ECC加密算法，可以通过以下命令安装：

sudo apt-get install libssl-dev

编译以上代码示例：

gcc -o ecc ecc.c -lssl -lcrypto

注意：以上代码示例仅供参考，实际使用时需要根据具体情况进行调整。