符合vs10环境用C++语言和openssl编写RSA算法的加密解密并附上每行代码注释

好的，以下是一个简单的使用OpenSSL库实现RSA加密解密的示例程序，附有详细的注释。但是需要说明的是，由于RSA算法本身的复杂性，这个示例程序只是提供了一个基本的框架，实际应用中可能需要根据具体需求进行修改。

#include <iostream>
#include <openssl/rsa.h>
#include <openssl/pem.h>
#include <openssl/err.h>

using namespace std;

int main() {
    // 初始化OpenSSL库
    OpenSSL_add_all_algorithms();
    ERR_load_crypto_strings();

    // 生成RSA密钥对
    RSA* rsa_keypair = RSA_generate_key(2048, RSA_F4, NULL, NULL);
    if (rsa_keypair == NULL) {
        cout << "Failed to generate RSA key pair." << endl;
        return 1;
    }

    // 获得公钥和私钥
    BIO* bio_pubkey = BIO_new(BIO_s_mem());
    BIO* bio_privkey = BIO_new(BIO_s_mem());
    if (!PEM_write_bio_RSAPublicKey(bio_pubkey, rsa_keypair)) {
        cout << "Failed to write public key." << endl;
        return 1;
    }
    if (!PEM_write_bio_RSAPrivateKey(bio_privkey, rsa_keypair, NULL, NULL, 0, NULL, NULL)) {
        cout << "Failed to write private key." << endl;
        return 1;
    }

    // 读取公钥和私钥
    RSA* rsa_pubkey = PEM_read_bio_RSAPublicKey(bio_pubkey, NULL, NULL, NULL);
    RSA* rsa_privkey = PEM_read_bio_RSAPrivateKey(bio_privkey, NULL, NULL, NULL);
    if (rsa_pubkey == NULL || rsa_privkey == NULL) {
        cout << "Failed to read public key or private key." << endl;
        return 1;
    }

    // 待加密的明文
    unsigned char plaintext[] = "Hello, RSA!";
    int plaintext_len = strlen((char*)plaintext);

    // 分配足够的空间来容纳加密后的密文和解密后的明文
    unsigned char* ciphertext = (unsigned char*)malloc(RSA_size(rsa_pubkey));
    unsigned char* decryptedtext = (unsigned char*)malloc(RSA_size(rsa_privkey));

    // 使用公钥加密明文
    int ciphertext_len = RSA_public_encrypt(plaintext_len, plaintext, ciphertext, rsa_pubkey, RSA_PKCS1_PADDING);
    if (ciphertext_len == -1) {
        cout << "Failed to encrypt plaintext." << endl;
        return 1;
    }

    // 输出加密后的密文
    cout << "Ciphertext: ";
    for (int i = 0; i < ciphertext_len; i++) {
        printf("%02x", ciphertext[i]);
    }
    cout << endl;

    // 使用私钥解密密文
    int decryptedtext_len = RSA_private_decrypt(ciphertext_len, ciphertext, decryptedtext, rsa_privkey, RSA_PKCS1_PADDING);
    if (decryptedtext_len == -1) {
        cout << "Failed to decrypt ciphertext." << endl;
        return 1;
    }

    // 输出解密后的明文
    cout << "Decryptedtext: " << decryptedtext << endl;

    // 释放内存
    RSA_free(rsa_keypair);
    RSA_free(rsa_pubkey);
    RSA_free(rsa_privkey);
    BIO_free_all(bio_pubkey);
    BIO_free_all(bio_privkey);
    free(ciphertext);
    free(decryptedtext);

    // 清理OpenSSL库
    EVP_cleanup();
    ERR_free_strings();

    return 0;
}

希望这个示例程序能够帮助你理解RSA算法的基本原理和使用方法。