// Derive an encryption key from a user-supplied buffer
static HCRYPTKEY DeriveKey(const void *pKey, int nKeyLen)
{
HCRYPTHASH hHash = 0;
HCRYPTKEY hKey;
if (!pKey || !nKeyLen) return 0;
if (!InitializeProvider())
{
return MAXDWORD;
}
if (CryptCreateHash(g_hProvider, CALG_SHA1, 0, 0, &hHash))
{
if (CryptHashData(hHash, (LPBYTE)pKey, nKeyLen, 0))
{
CryptDeriveKey(g_hProvider, CALG_RC4, hHash, 0, &hKey);
}
CryptDestroyHash(hHash);
}
return hKey;
}
VOID
MupGetProviderInformation (
VOID
)
/*++
Routine Description:
This routine reads MUP information from the registry and saves it for
future use.
Arguments:
None.
Return Value:
None.
--*/
{
HANDLE handle;
NTSTATUS status;
UNICODE_STRING valueName;
UNICODE_STRING keyName;
OBJECT_ATTRIBUTES objectAttributes;
PVOID buffer = NULL;
PWCH providerName;
ULONG lengthRequired;
BOOLEAN done;
ULONG priority;
PWCH sep;
PAGED_CODE();
RtlInitUnicodeString( &keyName, L"\\Registry\\Machine\\System\\CurrentControlSet\\Control\\Networkprovider\\Order" );
InitializeObjectAttributes(
&objectAttributes,
&keyName,
OBJ_CASE_INSENSITIVE,
0,
NULL
);
status = ZwOpenKey(
&handle,
KEY_QUERY_VALUE,
&objectAttributes
);
if ( !NT_SUCCESS( status )) {
return;
}
RtlInitUnicodeString( &valueName, L"ProviderOrder" );
status = ZwQueryValueKey(
handle,
&valueName,
KeyValueFullInformation,
buffer,
0,
&lengthRequired
);
if ( status == STATUS_BUFFER_TOO_SMALL ) {
buffer = ExAllocatePoolWithTag( PagedPool, lengthRequired + 2, ' puM');
if ( buffer == NULL) {
return;
}
status = ZwQueryValueKey(
handle,
&valueName,
KeyValueFullInformation,
buffer,
lengthRequired,
&lengthRequired
);
}
ZwClose( handle );
if ( !NT_SUCCESS( status) ) {
if ( buffer != NULL ) {
ExFreePool( buffer );
}
return;
}
//
// Scan the ordered list of providers, and create record for each.
//
providerName = (PWCH)((PCHAR)buffer + ((PKEY_VALUE_FULL_INFORMATION)buffer)->DataOffset);
done = FALSE;
priority = 0;
while ( !done ) {
sep = wcschr( providerName, L',');
if ( sep == NULL ) {
done = TRUE;
} else {
*sep = L'\0';
}
InitializeProvider( providerName, priority );
priority++;
providerName = sep+1;
}
ExFreePool( buffer );
return;
}
