Windows CAPI CryptDecrypt error key not working - c++

Question

I am trying to decrypt data from openssl generated private key. I have converted the public key from PEM to DER format, but when i use CryptDecrypt it throws error key does not exist. I have previously used the same method to encrypt data and decrypt using openssl, i am also aware regarding the Endianess difference in openssl and wincrypto. Here is the code if someone can point out where i am going wrong.
#include <Windows.h>
#include <wincrypt.h>
#include <stdio.h>
#pragma comment(lib, "Crypt32.lib")
char default_pub_key[] =
"-----BEGIN PUBLIC KEY-----"
"MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDVTOXB/Ti8SFvP42Z1XFB6GQ+R"
"jnqs42XiTFRXWpsSTlSPMRHi8aXpf1KYzzKHMC+4hU3rrgdbOu8bl7FekDoy38No"
"PX8ACoEmRhdn8mXs+ftmIRCuEE44mtgWUme65A1nTyT8nRmAVF6roo/rry+Xkbe9"
"iC6vRBRbVzprmCv7jwIDAQAB"
"-----END PUBLIC KEY-----";
HCRYPTPROV hProv = NULL;
HCRYPTKEY hKey = NULL;
DWORD dwKeySize = 0;
void SwapBytes(char* pv, size_t n) {
char* p = pv;
size_t lo, hi;
for (lo = 0, hi = n - 1; hi > lo; lo++, hi--)
{
char tmp = p[lo];
p[lo] = p[hi];
p[hi] = tmp;
}
}
int init_crypto()
{
LPBYTE pbBuffer;
DWORD dwKeyBlob, dw_pub_key_len = 0;
unsigned int offset = 22; // 22 = 1024, 24 = 2048 and so on
DWORD dwParamSize = sizeof(DWORD);
CERT_PUBLIC_KEY_INFO* publicKeyInfo;
CryptStringToBinaryA(default_pub_key, 0, CRYPT_STRING_ANY, NULL, &dw_pub_key_len, NULL, NULL);
pbBuffer = (LPBYTE)GlobalAlloc(GPTR, dw_pub_key_len);
CryptStringToBinaryA(default_pub_key, 0, CRYPT_STRING_ANY, pbBuffer, &dw_pub_key_len, NULL, NULL);
dwKeyBlob = 0;
CryptDecodeObjectEx(X509_ASN_ENCODING, X509_PUBLIC_KEY_INFO, pbBuffer, dw_pub_key_len, 0, NULL, NULL, &dwKeyBlob);
publicKeyInfo = (CERT_PUBLIC_KEY_INFO*)GlobalAlloc(GPTR, dwKeyBlob);
CryptDecodeObjectEx(X509_ASN_ENCODING, X509_PUBLIC_KEY_INFO, pbBuffer, dw_pub_key_len, 0, NULL, publicKeyInfo, &dwKeyBlob);
CryptAcquireContext(&hProv, NULL, MS_ENHANCED_PROV, PROV_RSA_FULL, CRYPT_VERIFYCONTEXT);
CryptImportPublicKeyInfo(hProv, X509_ASN_ENCODING, publicKeyInfo, &hKey);
CryptGetKeyParam(hKey, KP_KEYLEN, (BYTE*)&dwKeySize, &dwParamSize, 0);
char da[16];
memset(da, 0, sizeof(da));
wsprintfA(da, "%d", dwKeySize);
MessageBoxA(NULL, da, NULL, MB_OK);
dwKeySize /= 8;
return 0;
}
int main(int argc, char** argv)
{
// start rsa crypto key
init_crypto();
// Read encrypted data
DWORD junk;
HANDLE hEncFile = CreateFile(L"test_enc.txt", GENERIC_READ, 0, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
DWORD EncFileSize = GetFileSize(hEncFile, 0);
char* EncFileBuf = (char*)GlobalAlloc(GPTR, EncFileSize + 1);
ReadFile(hEncFile, EncFileBuf, EncFileSize, &junk, NULL);
CloseHandle(hEncFile);
// convert for win32
SwapBytes((char*)EncFileBuf, EncFileSize);
CryptDecrypt(hKey, 0, TRUE, 0,(PBYTE)EncFileBuf, &EncFileSize);
hEncFile = CreateFile(L"test_dec.txt", GENERIC_WRITE, 0, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);
WriteFile(hEncFile, EncFileBuf, EncFileSize, &junk, NULL);
CloseHandle(hEncFile);
GlobalFree(EncFileBuf);
// Do proper cleanup
return 0;
}

Answer 1

CryptDecrypt
[in] hKey
A handle to the key to use for the decryption. An application obtains this handle by using either the CryptGenKey or CryptImportKey function.
You pass a wrong hKey to CryptDecrypt. Use CryptImportKey after CryptImportPublicKeyInfo for getting an expected hKey and pass it to CryptDecrypt.