Source code of Windows XP (NT5)
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//#include <StdAfx.h>
#include "AdmtCrypt.h"
#include <NtSecApi.h>
#pragma comment( lib, "AdvApi32.lib" )
namespace AdmtCrypt2
{
#define SESSION_KEY_SIZE 16 // in bytes
HCRYPTKEY __stdcall DeriveEncryptionKey(HCRYPTPROV hProvider);
bool __stdcall IsDataMatchHash(HCRYPTPROV hProvider, const _variant_t& vntData, const _variant_t& vntHash);
// Provider Methods
HCRYPTKEY __stdcall DeriveKey(HCRYPTPROV hProvider, const _variant_t& vntBytes);
HCRYPTHASH __stdcall CreateHash(HCRYPTPROV hProvider);
bool __stdcall GenRandom(HCRYPTPROV hProvider, BYTE* pbData, DWORD cbData);
// Key Methods
void __stdcall DestroyKey(HCRYPTKEY hKey);
bool __stdcall Decrypt(HCRYPTKEY hKey, const _variant_t& vntEncrypted, _variant_t& vntDecrypted);
// Hash Methods
void __stdcall DestroyHash(HCRYPTHASH hHash);
bool __stdcall HashData(HCRYPTHASH hHash, const _variant_t& vntData);
// Miscellaneous Helpers
bool __stdcall RetrieveEncryptionBytes(_variant_t& vntBytes);
// Variant Helpers
bool __stdcall CreateByteArray(DWORD cb, _variant_t& vntByteArray);
}
using namespace AdmtCrypt2;
//---------------------------------------------------------------------------
// Source Crypt API
//---------------------------------------------------------------------------
// AdmtAcquireContext Method
HCRYPTPROV __stdcall AdmtAcquireContext()
{
HCRYPTPROV hProvider = 0;
BOOL bAcquire = CryptAcquireContext(
&hProvider,
NULL,
MS_ENHANCED_PROV,
PROV_RSA_FULL,
CRYPT_MACHINE_KEYSET|CRYPT_VERIFYCONTEXT
);
if (!bAcquire)
{
hProvider = 0;
}
return hProvider;
}
// AdmtReleaseContext Method
void __stdcall AdmtReleaseContext(HCRYPTPROV hProvider)
{
if (hProvider)
{
CryptReleaseContext(hProvider, 0);
}
}
// AdmtImportSessionKey Method
HCRYPTKEY __stdcall AdmtImportSessionKey(HCRYPTPROV hProvider, const _variant_t& vntEncryptedSessionBytes)
{
HCRYPTKEY hSessionKey = 0;
if (hProvider && (vntEncryptedSessionBytes.vt == (VT_UI1|VT_ARRAY)) && ((vntEncryptedSessionBytes.parray != NULL)))
{
HCRYPTKEY hEncryptionKey = DeriveEncryptionKey(hProvider);
if (hEncryptionKey)
{
_variant_t vntDecryptedSessionBytes;
if (Decrypt(hEncryptionKey, vntEncryptedSessionBytes, vntDecryptedSessionBytes))
{
if (vntDecryptedSessionBytes.parray->rgsabound[0].cElements > SESSION_KEY_SIZE)
{
// extract session key bytes
_variant_t vntBytes;
if (CreateByteArray(SESSION_KEY_SIZE, vntBytes))
{
memcpy(vntBytes.parray->pvData, vntDecryptedSessionBytes.parray->pvData, SESSION_KEY_SIZE);
// extract hash of session key bytes
_variant_t vntHashValue;
DWORD cbHashValue = vntDecryptedSessionBytes.parray->rgsabound[0].cElements - SESSION_KEY_SIZE;
if (CreateByteArray(cbHashValue, vntHashValue))
{
memcpy(vntHashValue.parray->pvData, (BYTE*)vntDecryptedSessionBytes.parray->pvData + SESSION_KEY_SIZE, cbHashValue);
if (IsDataMatchHash(hProvider, vntBytes, vntHashValue))
{
hSessionKey = DeriveKey(hProvider, vntBytes);
}
}
}
}
else
{
SetLastError(ERROR_INVALID_PARAMETER);
}
}
DestroyKey(hEncryptionKey);
}
}
else
{
SetLastError(ERROR_INVALID_PARAMETER);
}
return hSessionKey;
}
// AdmtDecrypt Method
_bstr_t __stdcall AdmtDecrypt(HCRYPTKEY hSessionKey, const _variant_t& vntEncrypted)
{
BSTR bstr = NULL;
_variant_t vntDecrypted;
if (Decrypt(hSessionKey, vntEncrypted, vntDecrypted))
{
HRESULT hr = BstrFromVector(vntDecrypted.parray, &bstr);
if (FAILED(hr))
{
SetLastError(ERROR_NOT_ENOUGH_MEMORY);
}
}
return bstr;
}
// AdmtDestroyKey Method
void __stdcall AdmtDestroyKey(HCRYPTKEY hKey)
{
DestroyKey(hKey);
}
//---------------------------------------------------------------------------
// Private Helpers
//---------------------------------------------------------------------------
namespace AdmtCrypt2
{
HCRYPTKEY __stdcall DeriveEncryptionKey(HCRYPTPROV hProvider)
{
HCRYPTKEY hKey = 0;
_variant_t vntBytes;
if (RetrieveEncryptionBytes(vntBytes))
{
hKey = DeriveKey(hProvider, vntBytes);
}
return hKey;
}
bool __stdcall IsDataMatchHash(HCRYPTPROV hProvider, const _variant_t& vntData, const _variant_t& vntHash)
{
bool bMatch = false;
HCRYPTHASH hHash = CreateHash(hProvider);
if (hHash)
{
if (HashData(hHash, vntData))
{
DWORD dwSizeA;
DWORD cbSize = sizeof(DWORD);
if (CryptGetHashParam(hHash, HP_HASHSIZE, (BYTE*)&dwSizeA, &cbSize, 0))
{
DWORD dwSizeB = vntHash.parray->rgsabound[0].cElements;
if (dwSizeA == dwSizeB)
{
try
{
BYTE* pbA = (BYTE*) _alloca(dwSizeA);
if (CryptGetHashParam(hHash, HP_HASHVAL, pbA, &dwSizeA, 0))
{
BYTE* pbB = (BYTE*) vntHash.parray->pvData;
if (memcmp(pbA, pbB, dwSizeA) == 0)
{
bMatch = true;
}
}
}
catch (...)
{
SetLastError(ERROR_NOT_ENOUGH_MEMORY);
}
}
}
}
}
return bMatch;
}
// Provider Methods
HCRYPTKEY __stdcall DeriveKey(HCRYPTPROV hProvider, const _variant_t& vntBytes)
{
HCRYPTKEY hKey = 0;
HCRYPTHASH hHash = CreateHash(hProvider);
if (hHash)
{
if (HashData(hHash, vntBytes))
{
if (!CryptDeriveKey(hProvider, CALG_3DES, hHash, 0, &hKey))
{
hKey = 0;
}
}
DestroyHash(hHash);
}
return hKey;
}
HCRYPTHASH __stdcall CreateHash(HCRYPTPROV hProvider)
{
HCRYPTHASH hHash;
if (!CryptCreateHash(hProvider, CALG_SHA1, 0, 0, &hHash))
{
hHash = 0;
}
return hHash;
}
bool __stdcall GenRandom(HCRYPTPROV hProvider, BYTE* pbData, DWORD cbData)
{
return CryptGenRandom(hProvider, cbData, pbData) ? true : false;
}
// Key Methods --------------------------------------------------------------
// DestroyKey Method
void __stdcall DestroyKey(HCRYPTKEY hKey)
{
if (hKey)
{
CryptDestroyKey(hKey);
}
}
// Decrypt Method
bool __stdcall Decrypt(HCRYPTKEY hKey, const _variant_t& vntEncrypted, _variant_t& vntDecrypted)
{
bool bDecrypted = false;
_variant_t vnt = vntEncrypted;
if ((vnt.vt == (VT_UI1|VT_ARRAY)) && (vnt.parray != NULL))
{
// decrypt data
BYTE* pb = (BYTE*) vnt.parray->pvData;
DWORD cb = vnt.parray->rgsabound[0].cElements;
if (CryptDecrypt(hKey, NULL, TRUE, 0, pb, &cb))
{
// create decrypted byte array
// the number of decrypted bytes may be less than
// the number of encrypted bytes
vntDecrypted.parray = SafeArrayCreateVector(VT_UI1, 0, cb);
if (vntDecrypted.parray != NULL)
{
vntDecrypted.vt = VT_UI1|VT_ARRAY;
memcpy(vntDecrypted.parray->pvData, vnt.parray->pvData, cb);
bDecrypted = true;
}
else
{
SetLastError(ERROR_NOT_ENOUGH_MEMORY);
}
}
}
else
{
SetLastError(ERROR_INVALID_PARAMETER);
}
return bDecrypted;
}
// Hash Methods -------------------------------------------------------------
// DestroyHash Method
void __stdcall DestroyHash(HCRYPTHASH hHash)
{
if (hHash)
{
CryptDestroyHash(hHash);
}
}
// HashData Method
bool __stdcall HashData(HCRYPTHASH hHash, const _variant_t& vntData)
{
bool bHash = false;
if ((vntData.vt == (VT_UI1|VT_ARRAY)) && ((vntData.parray != NULL)))
{
if (CryptHashData(hHash, (BYTE*)vntData.parray->pvData, vntData.parray->rgsabound[0].cElements, 0))
{
bHash = true;
}
}
else
{
SetLastError(ERROR_INVALID_PARAMETER);
}
return bHash;
}
// Miscellaneous Helpers ----------------------------------------------------
// RetrieveEncryptionBytes Method
bool __stdcall RetrieveEncryptionBytes(_variant_t& vntBytes)
{
// private data key identifier
_TCHAR c_szIdPrefix[] = _T("L$6A2899C0-CECE-459A-B5EB-7ED04DE61388");
const USHORT c_cbIdPrefix = sizeof(c_szIdPrefix) - sizeof(_TCHAR);
bool bRetrieve = false;
// open policy object
LSA_HANDLE hPolicy;
LSA_OBJECT_ATTRIBUTES lsaoa = { sizeof(LSA_OBJECT_ATTRIBUTES), NULL, NULL, 0, NULL, NULL };
NTSTATUS ntsStatus = LsaOpenPolicy(NULL, &lsaoa, POLICY_GET_PRIVATE_INFORMATION, &hPolicy);
if (LSA_SUCCESS(ntsStatus))
{
// retrieve data
LSA_UNICODE_STRING lsausKey = { c_cbIdPrefix, c_cbIdPrefix, c_szIdPrefix };
PLSA_UNICODE_STRING plsausData;
ntsStatus = LsaRetrievePrivateData(hPolicy, &lsausKey, &plsausData);
if (LSA_SUCCESS(ntsStatus))
{
vntBytes.Clear();
vntBytes.parray = SafeArrayCreateVector(VT_UI1, 0, plsausData->Length);
if (vntBytes.parray != NULL)
{
vntBytes.vt = VT_UI1|VT_ARRAY;
memcpy(vntBytes.parray->pvData, plsausData->Buffer, plsausData->Length);
bRetrieve = true;
}
else
{
SetLastError(ERROR_NOT_ENOUGH_MEMORY);
}
LsaFreeMemory(plsausData);
}
else
{
SetLastError(LsaNtStatusToWinError(ntsStatus));
}
// close policy object
LsaClose(hPolicy);
}
else
{
SetLastError(LsaNtStatusToWinError(ntsStatus));
}
return bRetrieve;
}
// Variant Helpers ----------------------------------------------------------
// CreateByteArray Method
bool __stdcall CreateByteArray(DWORD cb, _variant_t& vntByteArray)
{
bool bCreate = false;
vntByteArray.Clear();
vntByteArray.parray = SafeArrayCreateVector(VT_UI1, 0, cb);
if (vntByteArray.parray)
{
bCreate = true;
}
else
{
SetLastError(ERROR_NOT_ENOUGH_MEMORY);
}
vntByteArray.vt = VT_UI1|VT_ARRAY;
return bCreate;
}
}