Setting a Credential
The following code example:
- Calls GetCurrentUserIdentity to retrieve a WINBIO_IDENTITY object for the current user. GetCurrentUserIdentity is a helper function and is not part of the Windows Biometric Framework.
- Calls the GetCredentials helper function to retrieve a byte array that contains authentication information. GetCredentials displays a dialog box that prompts the user for credentials.
- Calls WinBioSetCredential to save the credentials in the store.
To compile this function link to the Winbio.lib static library and include the following header files:
- Windows.h
- Wincred.h
- Stdio.h
- Conio.h
- Winbio.h
HRESULT SetCredential()
{
// Declare variables.
HRESULT hr = S_OK;
ULONG ulAuthPackage = 0;
PVOID pvAuthBlob = NULL;
ULONG cbAuthBlob = 0;
WINBIO_IDENTITY identity;
PSID pSid = NULL;
// Find the identity of the user.
wprintf_s(L"\n Finding user identity.\n");
hr = GetCurrentUserIdentity( &identity );
if (FAILED(hr))
{
wprintf_s(L"\n User identity not found. hr = 0x%x\n", hr);
return hr;
}
// Set a pointer to the security descriptor for the user.
pSid = identity.Value.AccountSid.Data;
// Retrieve a byte array that contains credential information.
hr = GetCredentials(pSid, &pvAuthBlob, &cbAuthBlob);
if (FAILED(hr))
{
wprintf_s(L"\n GetCredentials failed. hr = 0x%x\n", hr);
goto e_Exit;
}
// Set the credentials.
hr = WinBioSetCredential(
WINBIO_CREDENTIAL_PASSWORD, // Type of credential.
(PUCHAR)pvAuthBlob, // Credentials byte array
cbAuthBlob, // Size of credentials
WINBIO_PASSWORD_PACKED); // Credentials format
if (FAILED(hr))
{
wprintf_s(L"\n WinBioSetCredential failed. hr = 0x%x\n", hr);
goto e_Exit;
}
wprintf_s(L"\n Credentials successfully set.\n");
e_Exit:
// Delete the authentication byte array.
if (NULL != pvAuthBlob)
{
SecureZeroMemory(pvAuthBlob, cbAuthBlob);
CoTaskMemFree(pvAuthBlob);
pvAuthBlob = NULL;
}
wprintf_s(L"\n Press any key to exit...");
_getch();
return hr;
}
//------------------------------------------------------------------------
// The following function displays a dialog box to prompt a user
// for credentials.
//
HRESULT GetCredentials(PSID pSid, PVOID* ppvAuthBlob, ULONG* pcbAuthBlob)
{
HRESULT hr = S_OK;
DWORD dwResult;
WCHAR szUsername[MAX_PATH] = {0};
DWORD cchUsername = ARRAYSIZE(szUsername);
WCHAR szPassword[MAX_PATH] = {0};
WCHAR szDomain[MAX_PATH] = {0};
DWORD cchDomain = ARRAYSIZE(szDomain);
WCHAR szDomainAndUser[MAX_PATH] = {0};
DWORD cchDomainAndUser = ARRAYSIZE(szDomainAndUser);
PVOID pvInAuthBlob = NULL;
ULONG cbInAuthBlob = 0;
PVOID pvAuthBlob = NULL;
ULONG cbAuthBlob = 0;
CREDUI_INFOW ui;
ULONG ulAuthPackage = 0;
BOOL fSave = FALSE;
static const WCHAR WINBIO_CREDPROV_TEST_PASSWORD_PROMPT_MESSAGE[] =
L"Enter your current password to enable biometric logon.";
static const WCHAR WINBIO_CREDPROV_TEST_PASSWORD_PROMPT_CAPTION[] =
L"Biometric Log On Enrollment";
if (NULL == pSid || NULL == ppvAuthBlob || NULL == pcbAuthBlob)
{
return E_INVALIDARG;
}
// Retrieve the user name and domain name.
SID_NAME_USE SidUse;
DWORD cchTmpUsername = cchUsername;
DWORD cchTmpDomain = cchDomain;
if (!LookupAccountSidW(
NULL, // Local computer
pSid, // Security identifier for user
szUsername, // User name
&cchTmpUsername, // Size of user name
szDomain, // Domain name
&cchTmpDomain, // Size of domain name
&SidUse)) // Account type
{
dwResult = GetLastError();
hr = HRESULT_FROM_WIN32(dwResult);
wprintf_s(L"\n LookupAccountSidLocalW failed: hr = 0x%x\n", hr);
return hr;
}
// Combine the domain and user names.
swprintf_s(
szDomainAndUser,
cchDomainAndUser,
L"%s\\%s",
szDomain,
szUsername);
// Call CredPackAuthenticationBufferW once to determine the size,
// in bytes, of the authentication buffer.
if (!CredPackAuthenticationBufferW(
0, // Reserved
szDomainAndUser, // Domain\User name
szPassword, // User Password
NULL, // Packed credentials
&cbInAuthBlob) // Size, in bytes, of credentials
&& GetLastError() != ERROR_INSUFFICIENT_BUFFER)
{
dwResult = GetLastError();
hr = HRESULT_FROM_WIN32(dwResult);
wprintf_s(L"\n CredPackAuthenticationBufferW (1) failed: ");
wprintf_s(L"hr = 0x%x\n", hr);
}
// Allocate memory for the input buffer.
pvInAuthBlob = CoTaskMemAlloc(cbInAuthBlob);
if (!pvInAuthBlob)
{
cbInAuthBlob = 0;
wprintf_s(L"\n CoTaskMemAlloc() Out of memory.\n");
return HRESULT_FROM_WIN32(ERROR_OUTOFMEMORY);
}
// Call CredPackAuthenticationBufferW again to retrieve the
// authentication buffer.
if (!CredPackAuthenticationBufferW(
0,
szDomainAndUser,
szPassword,
(PBYTE)pvInAuthBlob,
&cbInAuthBlob))
{
dwResult = GetLastError();
hr = HRESULT_FROM_WIN32(dwResult);
wprintf_s(L"\n CredPackAuthenticationBufferW (2) failed: ");
wprintf_s(L"hr = 0x%x\n", hr);
goto e_Exit;
}
// Display a dialog box to request credentials.
ui.cbSize = sizeof(ui);
ui.hwndParent = GetConsoleWindow();
ui.pszMessageText = WINBIO_CREDPROV_TEST_PASSWORD_PROMPT_MESSAGE;
ui.pszCaptionText = WINBIO_CREDPROV_TEST_PASSWORD_PROMPT_CAPTION;
ui.hbmBanner = NULL;
dwResult = CredUIPromptForWindowsCredentialsW(
&ui, // Customizing information
0, // Error code to display
&ulAuthPackage, // Authorization package
pvInAuthBlob, // Credential byte array
cbInAuthBlob, // Size of credential input buffer
&pvAuthBlob, // Output credential byte array
&cbAuthBlob, // Size of credential byte array
&fSave, // Select the save check box.
CREDUIWIN_IN_CRED_ONLY |
CREDUIWIN_ENUMERATE_CURRENT_USER
);
if (dwResult != NO_ERROR)
{
hr = HRESULT_FROM_WIN32(dwResult);
wprintf_s(L"\n CredUIPromptForWindowsCredentials failed: ");
wprintf_s(L"0x%08x\n", dwResult);
goto e_Exit;
}
*ppvAuthBlob = pvAuthBlob;
*pcbAuthBlob = cbAuthBlob;
e_Exit:
// Delete the input authentication byte array.
if (pvInAuthBlob)
{
SecureZeroMemory(pvInAuthBlob, cbInAuthBlob);
CoTaskMemFree(pvInAuthBlob);
pvInAuthBlob = NULL;
};
return hr;
}
//------------------------------------------------------------------------
// The following function retrieves the identity of the current user.
// This is a helper function and is not part of the Windows Biometric
// Framework API.
//
HRESULT GetCurrentUserIdentity(__inout PWINBIO_IDENTITY Identity)
{
// Declare variables.
HRESULT hr = S_OK;
HANDLE tokenHandle = NULL;
DWORD bytesReturned = 0;
struct{
TOKEN_USER tokenUser;
BYTE buffer[SECURITY_MAX_SID_SIZE];
} tokenInfoBuffer;
// Zero the input identity and specify the type.
ZeroMemory( Identity, sizeof(WINBIO_IDENTITY));
Identity->Type = WINBIO_ID_TYPE_NULL;
// Open the access token associated with the
// current process
if (!OpenProcessToken(
GetCurrentProcess(), // Process handle
TOKEN_READ, // Read access only
&tokenHandle)) // Access token handle
{
DWORD win32Status = GetLastError();
wprintf_s(L"Cannot open token handle: %d\n", win32Status);
hr = HRESULT_FROM_WIN32(win32Status);
goto e_Exit;
}
// Zero the tokenInfoBuffer structure.
ZeroMemory(&tokenInfoBuffer, sizeof(tokenInfoBuffer));
// Retrieve information about the access token. In this case,
// retrieve a SID.
if (!GetTokenInformation(
tokenHandle, // Access token handle
TokenUser, // User for the token
&tokenInfoBuffer.tokenUser, // Buffer to fill
sizeof(tokenInfoBuffer), // Size of the buffer
&bytesReturned)) // Size needed
{
DWORD win32Status = GetLastError();
wprintf_s(L"Cannot query token information: %d\n", win32Status);
hr = HRESULT_FROM_WIN32(win32Status);
goto e_Exit;
}
// Copy the SID from the tokenInfoBuffer structure to the
// WINBIO_IDENTITY structure.
CopySid(
SECURITY_MAX_SID_SIZE,
Identity->Value.AccountSid.Data,
tokenInfoBuffer.tokenUser.User.Sid
);
// Specify the size of the SID and assign WINBIO_ID_TYPE_SID
// to the type member of the WINBIO_IDENTITY structure.
Identity->Value.AccountSid.Size = GetLengthSid(tokenInfoBuffer.tokenUser.User.Sid);
Identity->Type = WINBIO_ID_TYPE_SID;
e_Exit:
if (tokenHandle != NULL)
{
CloseHandle(tokenHandle);
}
return hr;
}