C++ openssl 进行base64加密和解密

C++ OpenSSL 库提供了 base64 编码和解码的函数，可以使用以下代码进行加密和解密：

#include <openssl/bio.h>
#include <openssl/evp.h>
#include <openssl/buffer.h>

std::string base64_encode(const std::string& input) {
    BIO *bio, *b64;
    BUF_MEM *bufferPtr;

    bio = BIO_new(BIO_s_mem());
    b64 = BIO_new(BIO_f_base64());
    bio = BIO_push(b64, bio);

    BIO_write(bio, input.c_str(), input.length());
    BIO_flush(bio);

    BIO_get_mem_ptr(bio, &bufferPtr);
    std::string output(bufferPtr->data, bufferPtr->length);

    BIO_free_all(bio);

    return output;
}

std::string base64_decode(const std::string& input) {
    BIO *bio, *b64;
    char buffer[input.size()];
    memset(buffer, 0, sizeof(buffer));

    bio = BIO_new_mem_buf(input.c_str(), input.size());
    b64 = BIO_new(BIO_f_base64());
    bio = BIO_push(b64, bio);

    BIO_read(bio, buffer, input.size());

    BIO_free_all(bio);

    return std::string(buffer);
}

使用示例：

int main() {
    std::string input = "hello world";
    std::string encoded = base64_encode(input);
    std::string decoded = base64_decode(encoded);

    std::cout << "Input: " << input << std::endl;
    std::cout << "Encoded: " << encoded << std::endl;
    std::cout << "Decoded: " << decoded << std::endl;

    return 0;
}