rsa加解密全过程代码

RSA加密和解密的过程涉及到很多细节，包括密钥生成、加载以及实际的加密/解密操作。这里提供了一个简单的示例，使用OpenSSL库来演示RSA加密和解密过程：

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

// 加载公钥和私钥
void load_keys(const char *public_pem_path, const char *private_pem_path) {
    BIO *bio_pub, *bio_priv;
    RSA *rsa_pub, *rsa_priv;

    bio_pub = BIO_new_file(public_pem_path, "r");
    bio_priv = BIO_new_file(private_pem_path, "r");

    rsa_pub = PEM_read_bio_RSAPublicKey(bio_pub, NULL, NULL, NULL);
    rsa_priv = PEM_read_bio_RSAPrivateKey(bio_priv, NULL, NULL, NULL);

    if (!rsa_pub || !rsa_priv) {
        perror("Error loading keys");
        exit(1);
    }

    // 程序里可以在这里保存密钥，如果需要长期使用
    // 这里只是为了演示，不再保存
    BIO_free_all(bio_pub);
    BIO_free_all(bio_priv);
}

// 加密函数
char *encrypt_rsa(RSA *rsa_pub, const char *plaintext) {
    BIO *bio_out;
    unsigned char encrypted_data[EVP_MAX_MD_SIZE + 128];
    int encrypted_len;

    bio_out = BIO_new(BIO_s_mem());
    if (!BIO_write(bio_out, plaintext, strlen(plaintext))) {
        BIO_free_all(bio_out);
        return NULL;
    }
    
    if (RSA_public_encrypt(strlen(plaintext), bio_out->data, encrypted_data, rsa_pub, RSA_PKCS1_OAEP_PADDING) <= 0) {
        BIO_free_all(bio_out);
        return NULL;
    }
    
    encrypted_len = bio_out->length;
    encrypted_data[encrypted_len] = '\0';  // 添加终止符
    BIO_free_all(bio_out);

    return (char *) encrypted_data;
}

// 解密函数
char *decrypt_rsa(RSA *rsa_priv, const char *ciphertext) {
    BIO *bio_in = BIO_new_mem_buf((uint8_t *) ciphertext, strlen(ciphertext));
    unsigned char decrypted_data[EVP_MAX_MD_SIZE + 128];
    int decrypted_len;

    if (RSA_private_decrypt(strlen(ciphertext), bio_in->data, decrypted_data, rsa_priv, RSA_PKCS1_OAEP_PADDING) <= 0) {
        BIO_free_all(bio_in);
        return NULL;
    }

    decrypted_len = RSA_size(rsa_priv);
    decrypted_data[decrypted_len] = '\0';  // 添加终止符
    BIO_free_all(bio_in);

    return (char *) decrypted_data;
}

int main() {
    load_keys("path_to_public.pem", "path_to_private.pem");  // 替换为实际路径
    char *plaintext = "Hello, RSA!";
    char *encrypted = encrypt_rsa(<RSA_PUB_KEY>, plaintext);
    char *decrypted = decrypt_rsa(<RSA_PRIV_KEY>, encrypted);  // 用实际的私钥替换

    if (decrypted) {
        printf("Encrypted: %s\n", encrypted);
        printf("Decrypted: %s\n", decrypted);
    } else {
        printf("Failed to encrypt or decrypt.\n");
    }

    free(encrypted);
    free(decrypted);

    return 0;
}

注意：这个例子假设了公钥和私钥文件已存在，并且`<RSA_PUB_KEY>`和`<RSA_PRIV_KEY>`需要替换为你实际的RSA密钥变量。在实际项目中，你需要处理可能出现的各种错误情况。