linuxC++使用server端使用openssl加密一个文件，并通过https发送到client，client使用openssl解密，写一个例子

以下是一个简单的示例，演示如何在Linux C++中使用OpenSSL加密文件并通过HTTPS发送到客户端，然后使用OpenSSL解密。

Server端加密文件并发送：

#include <openssl/ssl.h>
#include <openssl/err.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#define PORT 443
#define CERTIFICATE "server.crt"
#define PRIVATE_KEY "server.key"
#define BUFFER_SIZE 1024

int main() {
    // 初始化SSL库
    SSL_library_init();

    // 创建SSL上下文
    SSL_CTX* ssl_ctx = SSL_CTX_new(TLSv1_2_server_method());

    // 加载证书和私钥
    SSL_CTX_use_certificate_file(ssl_ctx, CERTIFICATE, SSL_FILETYPE_PEM);
    SSL_CTX_use_PrivateKey_file(ssl_ctx, PRIVATE_KEY, SSL_FILETYPE_PEM);

    // 创建socket
    int server_socket = socket(AF_INET, SOCK_STREAM, 0);
    if (server_socket < 0) {
        perror("socket");
        exit(EXIT_FAILURE);
    }

    // 绑定端口
    struct sockaddr_in server_address;
    server_address.sin_family = AF_INET;
    server_address.sin_addr.s_addr = INADDR_ANY;
    server_address.sin_port = htons(PORT);

    if (bind(server_socket, (struct sockaddr*)&server_address, sizeof(server_address)) < 0) {
        perror("bind");
        exit(EXIT_FAILURE);
    }

    // 监听端口
    if (listen(server_socket, 1) < 0) {
        perror("listen");
        exit(EXIT_FAILURE);
    }

    // 接受连接请求
    struct sockaddr_in client_address;
    socklen_t client_address_size = sizeof(client_address);
    int client_socket = accept(server_socket, (struct sockaddr*)&client_address, &client_address_size);
    if (client_socket < 0) {
        perror("accept");
        exit(EXIT_FAILURE);
    }

    // 创建SSL连接
    SSL* ssl = SSL_new(ssl_ctx);
    SSL_set_fd(ssl, client_socket);
    SSL_accept(ssl);

    // 打开要加密的文件
    FILE* input_file = fopen("input_file.txt", "rb");
    if (input_file == NULL) {
        perror("fopen");
        exit(EXIT_FAILURE);
    }

    // 创建缓存区
    unsigned char buffer[BUFFER_SIZE];

    // 加密并发送文件
    int bytes_read = 0;
    int bytes_sent = 0;
    do {
        bytes_read = fread(buffer, 1, BUFFER_SIZE, input_file);
        if (bytes_read > 0) {
            int bytes_encrypted = SSL_write(ssl, buffer, bytes_read);
            if (bytes_encrypted < 0) {
                perror("SSL_write");
                exit(EXIT_FAILURE);
            }
            bytes_sent += bytes_encrypted;
        }
    } while (bytes_read > 0);

    // 关闭文件和连接
    fclose(input_file);
    SSL_shutdown(ssl);
    SSL_free(ssl);
    SSL_CTX_free(ssl_ctx);
    close(client_socket);
    close(server_socket);

    printf("Sent %d bytes\n", bytes_sent);

    return 0;
}

Client端接收并解密文件：

#include <openssl/ssl.h>
#include <openssl/err.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#define IP_ADDRESS "127.0.0.1"
#define PORT 443
#define CA_CERTIFICATE "ca.crt"
#define BUFFER_SIZE 1024

int main() {
    // 初始化SSL库
    SSL_library_init();

    // 创建SSL上下文
    SSL_CTX* ssl_ctx = SSL_CTX_new(TLSv1_2_client_method());

    // 加载CA证书
    if (!SSL_CTX_load_verify_locations(ssl_ctx, CA_CERTIFICATE, NULL)) {
        perror("SSL_CTX_load_verify_locations");
        exit(EXIT_FAILURE);
    }

    // 创建socket
    int client_socket = socket(AF_INET, SOCK_STREAM, 0);
    if (client_socket < 0) {
        perror("socket");
        exit(EXIT_FAILURE);
    }

    // 连接到服务器
    struct sockaddr_in server_address;
    server_address.sin_family = AF_INET;
    server_address.sin_addr.s_addr = inet_addr(IP_ADDRESS);
    server_address.sin_port = htons(PORT);

    if (connect(client_socket, (struct sockaddr*)&server_address, sizeof(server_address)) < 0) {
        perror("connect");
        exit(EXIT_FAILURE);
    }

    // 创建SSL连接
    SSL* ssl = SSL_new(ssl_ctx);
    SSL_set_fd(ssl, client_socket);
    SSL_connect(ssl);

    // 打开要写入的文件
    FILE* output_file = fopen("output_file.txt", "wb");
    if (output_file == NULL) {
        perror("fopen");
        exit(EXIT_FAILURE);
    }

    // 创建缓存区
    unsigned char buffer[BUFFER_SIZE];

    // 接收并解密文件
    int bytes_received = 0;
    int bytes_decrypted = 0;
    do {
        bytes_received = SSL_read(ssl, buffer, BUFFER_SIZE);
        if (bytes_received > 0) {
            int bytes_written = fwrite(buffer, 1, bytes_received, output_file);
            if (bytes_written < bytes_received) {
                perror("fwrite");
                exit(EXIT_FAILURE);
            }
            bytes_decrypted += bytes_received;
        }
    } while (bytes_received > 0);

    // 关闭文件和连接
    fclose(output_file);
    SSL_shutdown(ssl);
    SSL_free(ssl);
    SSL_CTX_free(ssl_ctx);
    close(client_socket);

    printf("Received and decrypted %d bytes\n", bytes_decrypted);

    return 0;
}

在这个例子中，我们使用了TLSv1.2协议和HTTPS端口443。服务器使用私钥和证书来创建SSL上下文，监听端口并接受客户端连接。客户端使用SSL上下文来加载CA证书，连接到服务器并创建SSL连接。在服务器端，我们打开要加密的文件，然后将其分块加密并发送到客户端。在客户端，我们接收加密的数据，并将其解密到一个新文件中。