ECDH非对称加密C++
ECDH算法封装，基于openssl。
#pragma once
#include <string>
#include <openssl/ec.h>
#include <openssl/ecdh.h>
#include <openssl/evp.h>
class ECDHEncoder
{
private:
EC_KEY* m_ecKey{ nullptr };
EC_KEY* m_ecPeerPubKey{ nullptr };
public:
ECDHEncoder() {};
~ECDHEncoder() {
if (m_ecKey)
EC_KEY_free(m_ecKey);
if (m_ecPeerPubKey)
EC_KEY_free(m_ecPeerPubKey);
};
bool GenerateKey(int nid)
{
m_ecKey = EC_KEY_new_by_curve_name(nid);
if (m_ecKey == nullptr)
return false;
if (1 != EC_KEY_generate_key(m_ecKey))
{
EC_KEY_free(m_ecKey);
m_ecKey = nullptr;
return false;
}
return true;
}
std::string GetMyEncodedPoint(point_conversion_form_t type = POINT_CONVERSION_UNCOMPRESSED)
{
const EC_GROUP* group = EC_KEY_get0_group(m_ecKey);
const EC_POINT* pubKey = EC_KEY_get0_public_key(m_ecKey);
size_t field_len = EC_GROUP_get_degree(group);
size_t byte_len = (field_len + 7) / 8;
unsigned char* point_data = (unsigned char*)malloc(byte_len * 2 + 1);
if (!point_data)
return {};
size_t point_data_len = EC_POINT_point2oct(group, pubKey, type, point_data, byte_len * 2 + 1, nullptr);
if (0 == point_data_len)
{
free(point_data);
return {};
}
std::string strPointData((char*)point_data, point_data_len);
free(point_data);
return strPointData;
}
std::string GetMyPublicKey()
{
BIO* out = BIO_new(BIO_s_mem());
i2d_EC_PUBKEY_bio(out, m_ecKey);
char* p;
long length = BIO_get_mem_data(out, &p);
std::string strECPubKey(p, length);
BIO_free_all(out);
return strECPubKey;
}
bool SetPeerPublicKey(const std::string& strPeerPublicKey)
{
if (m_ecPeerPubKey)
{
EC_KEY_free(m_ecPeerPubKey);
m_ecPeerPubKey = nullptr;
}
const unsigned char* szBuf = (unsigned char*)strPeerPublicKey.c_str();
m_ecPeerPubKey = d2i_EC_PUBKEY(nullptr, &szBuf, (long)strPeerPublicKey.size());
if (m_ecPeerPubKey == nullptr)
return false;
return true;
}
bool SetPeerEncodedPoint(const std::string& strPointData)
{
if (m_ecPeerPubKey)
{
EC_KEY_free(m_ecPeerPubKey);
m_ecPeerPubKey = nullptr;
}
const EC_GROUP* group = EC_KEY_get0_group(m_ecKey);
EC_POINT* peerPubKey = EC_POINT_new(group);
if (peerPubKey == nullptr)
return false;
const unsigned char* p = (const unsigned char*)strPointData.c_str();
if (0 == EC_POINT_oct2point(group, peerPubKey, p, strPointData.size(), nullptr))
{
EC_POINT_free(peerPubKey);
return false;
}
m_ecPeerPubKey = EC_KEY_new_by_curve_name(EC_GROUP_get_curve_name(group));
if (m_ecPeerPubKey == nullptr)
{
EC_POINT_free(peerPubKey);
return false;
}
if (1 != EC_KEY_set_public_key(m_ecPeerPubKey, peerPubKey))
{
EC_POINT_free(peerPubKey);
EC_KEY_free(m_ecPeerPubKey);
m_ecPeerPubKey = nullptr;
return false;
}
EC_POINT_free(peerPubKey);
return true;
}
std::string ComputeSecretKey()
{
if (m_ecPeerPubKey == nullptr)
return {};
int field_size = EC_GROUP_get_degree(EC_KEY_get0_group(m_ecKey));
size_t secret_len = (field_size + 7) / 8;
unsigned char* secret = new unsigned char[secret_len];
if (secret == nullptr)
return {};
secret_len = ECDH_compute_key(secret, secret_len, EC_KEY_get0_public_key(m_ecPeerPubKey), m_ecKey, nullptr);
if (secret_len == 0)
{
delete[] secret;
return {};
}
std::string strSecretKey((const char*)secret, secret_len);
delete[] secret;
return strSecretKey;
}
};blackfeather 2024/12/16 ℃ 0评论