146 lines
3.9 KiB
C++
146 lines
3.9 KiB
C++
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#include "stdafx.h"
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#include "common.h"
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#include <wincrypt.h>
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#include <strsafe.h>
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#ifdef _DEBUG
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#undef THIS_FILE
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static char BASED_CODE THIS_FILE[] = __FILE__;
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#endif
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#define new DEBUG_NEW
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// Given a clear text password. this function will encrypt the password in memory
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// then allocate memory and passback the encrypted password into the memory
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//
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// The class can then store the ppszEncryptedPassword in it's member variables safely
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// and when the class is destructed, should SecureZeroMemory() out the password and LocalFree() up the the memory.
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HRESULT EncryptMemoryPassword(LPWSTR pszClearTextPassword,LPWSTR *ppszEncryptedPassword,DWORD *ppdwBufferBytes)
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{
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HRESULT hRes = E_FAIL;
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LPWSTR pszTempStr = NULL;
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DWORD dwTempStrSizeOf = 0;
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*ppszEncryptedPassword = NULL;
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*ppdwBufferBytes = 0;
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if (pszClearTextPassword)
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{
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// We should check if the pszClearTextPassword is null terminated before doing wcslen
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DWORD dwBufferByteLen = (wcslen(pszClearTextPassword) + 1) * sizeof(WCHAR);
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if (CRYPTPROTECTMEMORY_BLOCK_SIZE > 0 && dwBufferByteLen > 0)
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{
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int iBlocks = dwBufferByteLen / CRYPTPROTECTMEMORY_BLOCK_SIZE;
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iBlocks++;
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dwTempStrSizeOf = iBlocks * CRYPTPROTECTMEMORY_BLOCK_SIZE;
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pszTempStr = (LPWSTR) LocalAlloc(LPTR,dwTempStrSizeOf);
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if (!pszTempStr)
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{
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hRes = E_OUTOFMEMORY;
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goto EncryptMemoryPassword_Exit;
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}
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ZeroMemory(pszTempStr,dwTempStrSizeOf);
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StringCbCopy(pszTempStr,dwTempStrSizeOf,pszClearTextPassword);
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if (FALSE != CryptProtectMemory(pszTempStr,dwTempStrSizeOf,CRYPTPROTECTMEMORY_SAME_PROCESS))
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{
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// We're all set...
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*ppszEncryptedPassword = pszTempStr;
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*ppdwBufferBytes = dwTempStrSizeOf;
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hRes = S_OK;
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goto EncryptMemoryPassword_Exit;
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}
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}
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}
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EncryptMemoryPassword_Exit:
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if (FAILED(hRes))
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{
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if (pszTempStr)
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{
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if (dwTempStrSizeOf > 0)
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{
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SecureZeroMemory(pszTempStr,dwTempStrSizeOf);
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}
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LocalFree(pszTempStr);
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pszTempStr = NULL;
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dwTempStrSizeOf = 0;
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}
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}
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return hRes;
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}
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// Given a encrypted password (encrypted in the same process with EncryptMemoryPassword -- which uses CryptProtectMemory)
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// this function will allocate some new memory, decrypt the password and put it in the new memory
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// and return it back to the caller in ppszReturnedPassword.
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//
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// The caller must ensure to erase and free the memory after it is finished using the decrypted password.
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//
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// LPWSTR lpwstrTempPassword = NULL;
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//
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// if (FAILED(DecryptMemoryPassword((LPWSTR) pszUserPasswordEncrypted,&lpwstrTempPassword,cbUserPasswordEncrypted)))
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// {
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// // do some failure processing...
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// }
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//
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// // use password for whatever you needed to use it for...
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//
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// if (lpwstrTempPassword)
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// {
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// if (cbTempPassword > 0)
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// (
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// SecureZeroMemory(lpwstrTempPassword,cbTempPassword);
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// )
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// LocalFree(lpwstrTempPassword);lpwstrTempPassword = NULL;
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// }
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HRESULT DecryptMemoryPassword(LPWSTR pszEncodedPassword,LPWSTR *ppszReturnedPassword,DWORD dwBufferBytes)
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{
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HRESULT hRes = E_FAIL;
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LPWSTR pszTempStr = NULL;
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if (!dwBufferBytes || !ppszReturnedPassword)
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{
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return E_FAIL;
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}
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*ppszReturnedPassword = NULL;
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if (dwBufferBytes)
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{
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pszTempStr = (LPWSTR) LocalAlloc(LPTR,dwBufferBytes);
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if (!pszTempStr)
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{
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hRes = E_OUTOFMEMORY;
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goto DecryptMemoryPassword_Exit;
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}
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ZeroMemory(pszTempStr,dwBufferBytes);
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memcpy(pszTempStr,pszEncodedPassword,dwBufferBytes);
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if (FALSE != CryptUnprotectMemory(pszTempStr,dwBufferBytes,CRYPTPROTECTMEMORY_SAME_PROCESS))
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{
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// We're all set...
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*ppszReturnedPassword = pszTempStr;
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hRes = S_OK;
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}
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}
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DecryptMemoryPassword_Exit:
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if (FAILED(hRes))
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{
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if (pszTempStr)
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{
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if (dwBufferBytes > 0)
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{
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SecureZeroMemory(pszTempStr,dwBufferBytes);
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}
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LocalFree(pszTempStr);
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pszTempStr = NULL;
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}
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}
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return hRes;
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}
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