Windows环境下C#与C++之间的Diffie-Hellman密钥交换

Diffie Hellman key exchange between C# and C++ on Windows

本文关键字：之间 Diffie-Hellman 密钥交换 C++ 环境 Windows      更新时间：2024-09-27

我想使用Diffie Hellman算法在运行在Windows上的C++服务器和C#客户端之间安全地交换密钥。我尝试在C#中使用ECDiffieHellmanCng生成公钥，如下所示：

ECDiffieHellmanCng diffieHellman = new ECDiffieHellmanCng
{
KeyDerivationFunction = ECDiffieHellmanKeyDerivationFunction.Hash,
HashAlgorithm = CngAlgorithm.Sha256
};
byte[] publicKey = diffieHellman.PublicKey.ToByteArray(); // 140 bytes

此外，我使用以下代码推导AES key：

var cngKey = CngKey.Import(publicKey, CngKeyBlobFormat.EccPublicBlob);
var aesKey = diffieHellman.DeriveKeyMaterial(cngKey); // 32 bytes

这在C#上下文中运行良好，但我需要它与C++交互。

是否有与ECDiffieHellmanCng兼容的C++库或代码？我研究了Crypto++，但它希望我生成p、q和g，以及128字节的公钥大小，这看起来与我的C#密钥交换方法不兼容。

不管怎样，我们都欢迎为执行密钥交换提供任何其他建议或代码示例。

因为我只是想要一个加密的连接，所以使用OpenSSL是最好的选择。

也许这会对你有所帮助？

#pragma warning(disable : 4996)
#include <stdio.h>
#include <iostream>
#include <string>
#include <sstream>
#include "openssl/dh.h"
#include "openssl/bn.h"
#include "openssl/pem.h";
using namespace std;
DH *dhp = NULL;
static const std::string base64_chars =
"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"abcdefghijklmnopqrstuvwxyz"
"0123456789+/";
static inline bool is_base64(unsigned char c) {
return (isalnum(c) || (c == '+') || (c == '/'));
}
std::string base64_encode(unsigned char const* bytes_to_encode, unsigned int in_len) {
std::string ret;
int i = 0;
int j = 0;
unsigned char char_array_3[3];
unsigned char char_array_4[4];
while (in_len--) {
char_array_3[i++] = *(bytes_to_encode++);
if (i == 3) {
char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;
char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);
char_array_4[3] = char_array_3[2] & 0x3f;
for (i = 0; (i < 4); i++)
ret += base64_chars[char_array_4[i]];
i = 0;
}
}
if (i)
{
for (j = i; j < 3; j++)
char_array_3[j] = '';
char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;
char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);
char_array_4[3] = char_array_3[2] & 0x3f;
for (j = 0; (j < i + 1); j++)
ret += base64_chars[char_array_4[j]];
while ((i++ < 3))
ret += '=';
}
return ret;
}
std::string base64_decode(std::string const& encoded_string) {
int in_len = encoded_string.size();
int i = 0;
int j = 0;
int in_ = 0;
unsigned char char_array_4[4], char_array_3[3];
std::string ret;
while (in_len-- && (encoded_string[in_] != '=') && is_base64(encoded_string[in_])) {
char_array_4[i++] = encoded_string[in_]; in_++;
if (i == 4) {
for (i = 0; i < 4; i++)
char_array_4[i] = base64_chars.find(char_array_4[i]);
char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);
char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);
char_array_3[2] = ((char_array_4[2] & 0x3) << 6) + char_array_4[3];
for (i = 0; (i < 3); i++)
ret += char_array_3[i];
i = 0;
}
}
if (i) {
for (j = i; j < 4; j++)
char_array_4[j] = 0;
for (j = 0; j < 4; j++)
char_array_4[j] = base64_chars.find(char_array_4[j]);
char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);
char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);
char_array_3[2] = ((char_array_4[2] & 0x3) << 6) + char_array_4[3];
for (j = 0; (j < i - 1); j++) ret += char_array_3[j];
}
return ret;
}
int main(int argc, char *argv[])
{
BIGNUM* priv_key = NULL;
BIGNUM* apub_key = NULL;
BIGNUM* p = NULL;
BIGNUM* g = NULL;
std::string userPubKey;
std::string prime;
std::string generator;
if (argc < 6) {
printf("%s", "Missing parameters: -p, -key -g");
return -1;
}
//Process parameters
int count;
for (count = 1; count < argc; count+=2)
{
std::string param = (string)argv[count];
if (strcmpi(param.c_str(), "-p") == 0) {
prime = (string)argv[count+1];
}
else if (strcmpi(param.c_str(), "-key") == 0) {
userPubKey = (string)argv[count + 1];
}
else if (strcmpi(param.c_str(), "-g") == 0) {
generator = (string)argv[count+1];
}
}
//Set public key of remote User
BN_hex2bn(&apub_key, userPubKey.c_str());
DH *dhp = DH_new();
if (dhp == NULL) {
return -1;
}

//Set Prime and Generator
BN_hex2bn(&p, prime.c_str());
BN_dec2bn(&g, generator.c_str());
DH_set0_pqg(dhp, p, NULL, g);
if (DH_generate_key(dhp) != 1) {
printf("%s", "Error generating keys.");
return -1;
}
//Print Public Key as Hex
const BIGNUM* exportPublic = DH_get0_pub_key(dhp);
printf("Public Key: %srn", BN_bn2hex(exportPublic));
//Calculate secret
char buf[256] = { 0 };
unsigned char* abuf = NULL;
int alen = DH_size(dhp);
abuf = (unsigned char*)OPENSSL_malloc(alen);
int aout = DH_compute_key(abuf, apub_key, dhp);
printf("rnThe shared secret is:rn");
std::string encoded = base64_encode(abuf, aout);
printf("%srn", encoded.c_str());
DH_free(dhp);
p = NULL;
g = NULL;
abuf = NULL;
}
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