用c语言写出公钥和私钥生成的函数

在C语言中生成公钥和私钥通常使用OpenSSL库。以下是一个示例代码，展示了如何使用OpenSSL库生成RSA公钥和私钥：

#include <openssl/rsa.h>
#include <openssl/pem.h>
#include <openssl/err.h>
#include <stdio.h>
#include <string.h>

void handleErrors(void)
{
    ERR_print_errors_fp(stderr);
    abort();
}

int generateRSAKeyPair(unsigned int keyLength, FILE **publicKeyFile, FILE **privateKeyFile)
{
    RSA *rsa = NULL;
    BIGNUM *bn = NULL;
    BIO *bp_public = NULL, *bp_private = NULL;

    int ret = 0;

    // Initialize the OpenSSL library
    OpenSSL_add_all_algorithms();
    ERR_load_BIO_strings();
    ERR_load_crypto_strings();

    // Create a new RSA key
    rsa = RSA_new();
    if (rsa == NULL)
        handleErrors();

    bn = BN_new();
    if (bn == NULL)
        handleErrors();

    // Generate a random number
    ret = BN_set_word(bn, RSA_F4);
    if (ret != 1)
        handleErrors();

    // Generate the RSA key
    ret = RSA_generate_key_ex(rsa, keyLength, bn, NULL);
    if (ret != 1)
        handleErrors();

    // Write the public key to a file
    bp_public = BIO_new_file(publicKeyFile[0], "w+");
    if (bp_public == NULL)
        handleErrors();

    ret = PEM_write_bio_RSAPublicKey(bp_public, rsa);
    if (ret != 1)
        handleErrors();

    // Write the private key to a file
    bp_private = BIO_new_file(privateKeyFile[0], "w+");
    if (bp_private == NULL)
        handleErrors();

    ret = PEM_write_bio_RSAPrivateKey(bp_private, rsa, NULL, NULL, 0, NULL, NULL);
    if (ret != 1)
        handleErrors();

    // Clean up
    BIO_free(bp_public);
    BIO_free(bp_private);
    RSA_free(rsa);
    BN_free(bn);

    return 1;
}

int main()
{
    FILE *publicKeyFile = fopen("public_key.pem", "w");
    FILE *privateKeyFile = fopen("private_key.pem", "w");

    if (publicKeyFile == NULL || privateKeyFile == NULL) {
        printf("Error opening files for writing.\n");
        return 1;
    }

    if (generateRSAKeyPair(2048, &publicKeyFile, &privateKeyFile)) {
        printf("RSA key pair generated successfully.\n");
    } else {
        printf("Error generating RSA key pair.\n");
    }

    fclose(publicKeyFile);
    fclose(privateKeyFile);

    return 0;
}

这个示例代码使用了OpenSSL库来生成RSA公钥和私钥。你需要确保你的系统中已经安装了OpenSSL库，并在编译时链接OpenSSL库。例如：

gcc -o generate_keys generate_keys.c -lssl -lcrypto