Generation RSA-2048 keys (public and private) - c++

Question

I'm making simple implementation RSA-2048. I found some code on another forum.
#include <string>
#include <iostream>
#include <windows.h>
#include <Wincrypt.h>
using namespace std;
#pragma comment (lib, "Crypt32.lib")
BYTE* Crypt(const string& _str, DWORD* _outLength);
BYTE* Decrypt(BYTE* _encryptedData, DWORD* _length);
const char* szPemPrivKey =
"-----BEGIN RSA PRIVATE KEY-----"
"MIICWwIBAAKBgQCn7fL/1qsWkJkUtXKZIJNqYfnVByVhK/LzQecPhVR7r+4ng1nZ"
"Bxg44SexS63iYlnodqDWkH/Hi82Uc0UmugY/Ow39uEGeoiYqWl5BLM8pfRAGqzxb"
"h600Qd/Oc5kYdg8hP0D/gAHXwutL74fygpB6xb8EZl2BHKvpDR80GYFlrQIDAQAB"
"AoGAZ4ZHsfTTEFwgIyYg+cmdV44DCJMZNihz5AcSvPzDMmUo+m79as/23MnhQGmZ"
"TuC28JqBWQVH4OqM2CGf1doEkuLZ/rcgxDipRqbLkEW3T/q+kJ2m9A652ePbHUKX"
"ayozDQrWtL4wkvAQQ9Il6vx+AJUzT41hv1PKZ5KWxONiJDkCQQDRsObUVVc6exb+"
"YUWVgN0pivHudKIwGUN3js09MjHoen9LbUcvupO3seAUhnNQ17t+1XxsrnPKabQQ"
"OimcPK3XAkEAzQQEI++NdoLYJv1oKYADzOUbDAmfoZ/szN6z//53h8zt5ni+6Q0n"
"k7nyrVXWuLeP0rEvD0hMOzI0mfUMwbtwGwJAMUYId8y1+qAB/zSMTV1CmwhzYT02"
"/2ZwXB/KSp8I60AduXOsTqLhI0FBDpGpd026WUuBOWik/ONp1IZWUMhRcQJAHI+U"
"rBTxVjNAPZ5L5owo+2BndjPZA0EuUhQsa1td95M7CUKFBh6JBvF+t1sgALfB145L"
"igt+YzjJTzFuR4b/RQJATgZuFyBiuLHrMES2vAtmLRlF6uTzsrNZLLUko2Rfzkzh"
"qR4inQOWWZLFzjqp3ha9rzCSVY+nBw+xD+B9hBlsNw=="
"-----END RSA PRIVATE KEY-----";
const char* szPemPublicKey =
"-----BEGIN PUBLIC KEY-----"
"MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCn7fL/1qsWkJkUtXKZIJNqYfnV"
"ByVhK/LzQecPhVR7r+4ng1nZBxg44SexS63iYlnodqDWkH/Hi82Uc0UmugY/Ow39"
"uEGeoiYqWl5BLM8pfRAGqzxbh600Qd/Oc5kYdg8hP0D/gAHXwutL74fygpB6xb8E"
"Zl2BHKvpDR80GYFlrQIDAQAB"
"-----END PUBLIC KEY-----";
int main()
{
string str_data = "test RSA implementation";
DWORD encryptedDataLen;
BYTE* encrytedData = Crypt(str_data, &encryptedDataLen);
cout << encrytedData << endl;
cout << endl;
BYTE* decryptedData = Decrypt(encrytedData, &encryptedDataLen);
cout << decryptedData << endl;
delete(encrytedData);
delete(decryptedData);
return 0;
}
BYTE* Crypt(const string& _str, DWORD* _outLength)
{
char pemPubKey[2048];
memcpy((void*)pemPubKey, szPemPublicKey, strlen(szPemPublicKey));
char derPubKey[2048];
DWORD derPubKeyLen = 2048;
CERT_PUBLIC_KEY_INFO* publicKeyInfo;
DWORD publicKeyInfoLen;
HANDLE hFile;
HCRYPTPROV hProv = 0;
HCRYPTKEY hKey = 0;
// Convert from PEM format to DER format - removes header and footer and decodes from base64
if (!CryptStringToBinaryA(pemPubKey, 0, CRYPT_STRING_BASE64HEADER, (BYTE*)derPubKey, &derPubKeyLen, NULL, NULL))
{
fprintf(stderr, "CryptStringToBinary failed. Err: %d\n", GetLastError());
return NULL;
}
// Decode from DER format to CERT_PUBLIC_KEY_INFO
if (!CryptDecodeObjectEx(X509_ASN_ENCODING, X509_PUBLIC_KEY_INFO, (BYTE*)derPubKey, derPubKeyLen,
CRYPT_ENCODE_ALLOC_FLAG, NULL, &publicKeyInfo, &publicKeyInfoLen))
{
fprintf(stderr, "CryptDecodeObjectEx 1 failed. Err: %p\n", GetLastError());
return NULL;
}
if (!CryptAcquireContext(&hProv, NULL, NULL, PROV_RSA_FULL, CRYPT_VERIFYCONTEXT))
{
{
printf("CryptAcquireContext failed - err=0x%x.\n", GetLastError());
return NULL;
}
}
if (!CryptImportPublicKeyInfo(hProv, X509_ASN_ENCODING, publicKeyInfo, &hKey))
{
fprintf(stderr, "CryptImportPublicKeyInfo failed. error: %d\n", GetLastError());
return NULL;
}
// LocalFree( publicKeyInfo );
// get size of buffer
DWORD strLen = _str.length() * sizeof(char);
DWORD bufLen = strLen;
if (!CryptEncrypt(hKey, 0, true, 0, 0, &bufLen, strLen))
{
cout << "CryptEncrypt() failed with error " << GetLastError() << endl;
return NULL;
}
// Crypt string data
BYTE* cipherBlock = new BYTE[bufLen];
memset((void*)cipherBlock, 0, bufLen);
memcpy((void*)cipherBlock, _str.c_str(), strLen);
if (!CryptEncrypt(hKey, 0, TRUE, 0, cipherBlock, &strLen, bufLen))
{
cout << "CryptEncrypt() failed with error " << GetLastError() << endl;
return NULL;
}
*_outLength = bufLen;
return cipherBlock;
}
BYTE* Decrypt(BYTE* _encryptedData, DWORD* _length)
{
DWORD dwBufferLen = 0, cbKeyBlob = 0, cbSignature = 0/*,i*/;
LPBYTE pbBuffer = NULL, pbKeyBlob = NULL, pbSignature = NULL;
HCRYPTPROV hProv = NULL;
HCRYPTKEY hKey = NULL;
HCRYPTHASH hHash = NULL;
if (!CryptStringToBinaryA(szPemPrivKey, 0, CRYPT_STRING_BASE64HEADER, NULL, &dwBufferLen, NULL, NULL))
{
cout << "Failed to convert BASE64 private key. Error " << GetLastError() << endl;
return NULL;
}
pbBuffer = (LPBYTE)LocalAlloc(0, dwBufferLen);
if (!CryptStringToBinaryA(szPemPrivKey, 0, CRYPT_STRING_BASE64HEADER, pbBuffer, &dwBufferLen, NULL, NULL))
{
cout << "Failed to convert BASE64 private key. Error " << GetLastError() << endl;
return NULL;
}
if (!CryptDecodeObjectEx(X509_ASN_ENCODING | PKCS_7_ASN_ENCODING, PKCS_RSA_PRIVATE_KEY, pbBuffer, dwBufferLen, 0, NULL, NULL, &cbKeyBlob))
{
cout << "Failed to parse private key. Error " << GetLastError() << endl;
return NULL;
}
pbKeyBlob = (LPBYTE)LocalAlloc(0, cbKeyBlob);
if (!CryptDecodeObjectEx(X509_ASN_ENCODING | PKCS_7_ASN_ENCODING, PKCS_RSA_PRIVATE_KEY, pbBuffer, dwBufferLen, 0, NULL, pbKeyBlob, &cbKeyBlob))
{
cout << "Failed to parse private key. Error " << GetLastError() << endl;
return NULL;
}
if (!CryptAcquireContext(&hProv, NULL, MS_DEF_PROV, PROV_RSA_FULL, 0))
{
if (GetLastError() == NTE_BAD_KEYSET)
{
if (!CryptAcquireContext(&hProv, NULL, MS_DEF_PROV, PROV_RSA_FULL, CRYPT_NEWKEYSET))
{
cout << "CryptAcquireContext() failed with error " << GetLastError() << endl;
return NULL;
}
}
else
{
cout << "CryptAcquireContext() failed with error " << GetLastError() << endl;
return NULL;
}
}
if (!CryptImportKey(hProv, pbKeyBlob, cbKeyBlob, NULL, 0, &hKey))
{
cout << "CryptImportKey() failed with error " << GetLastError() << endl;
return NULL;
}
// Decrypt
DWORD bufLen = *_length + 1;
BYTE* cipherBlock = new BYTE[bufLen];
memset((void*)cipherBlock, 0, bufLen);
memcpy((void*)cipherBlock, _encryptedData, *_length);
if (!CryptDecrypt(hKey, 0, TRUE, 0, cipherBlock, _length))
{
cout << "CryptDecrypt() failed with error " << GetLastError() << endl;
return NULL;
}
// Decrypted data
BYTE* decryptedData = new BYTE[*_length + 1];
decryptedData[*_length] = 0;
memcpy((void*)decryptedData, cipherBlock, *_length);
delete(cipherBlock);
if (pbBuffer) LocalFree(pbBuffer);
if (pbKeyBlob) LocalFree(pbKeyBlob);
if (pbSignature) LocalFree(pbSignature);
if (hHash) CryptDestroyHash(hHash);
if (hKey) CryptDestroyKey(hKey);
if (hProv) CryptReleaseContext(hProv, 0);
return decryptedData;
}
So, encryption\decryption works perfectly well.
I need to change keys.
How can I generate keys for this code?
I tried this online generator but it doen't work.
https://travistidwell.com/jsencrypt/demo/
and other online generators

Answer 1

NCryptCreatePersistedKey . Please abandon old Crypt* functions in favor of NCrypt and BCrypt* variants. If you insist on the old API, use this.