Function derive_path_iv

libcppcryptfs/filename/cryptfilename.cpp:71–128

}

bool 
derive_path_iv(CryptContext *con, const WCHAR *path, unsigned char *iv, const char *type)
{

	//DbgPrint(L"derive_path_iv path = %s, type = %S\n", path, type);

	wstring wpath;

	const WCHAR *pathstr = path;

	if (*pathstr == '\\' || *pathstr == '/')
		pathstr++;

	wpath = pathstr;

	if (wpath.length() > 0) {
		if (wpath[wpath.length() - 1] == '\\' || wpath[wpath.length()] - 1 == '/')
			wpath.erase(wpath.length() - 1);
	}

	int i;
	int len = (int)wpath.length();
	for (i = 0; i < len; i++) {
		if (wpath[i] == '\\')
			wpath[i] = '/';
	}

	string utf8path;

	if (!unicode_to_utf8(&wpath[0], utf8path))
		return false;

	bool bRet = true;

	TempBuffer<BYTE, 4096> buffer;

	BYTE *pbuf = NULL;

	try {
		int typelen = (int)strlen(type);
		int bufsize = (int)(utf8path.length() + 1 + typelen);
		pbuf = buffer.get(bufsize);
		if (!pbuf)
			throw(-1);
		memcpy(pbuf, &utf8path[0], utf8path.length() + 1);
		memcpy(pbuf + utf8path.length() + 1, type, typelen);
		BYTE hash[SHA256_LEN];
		if (!sha256(pbuf, bufsize, hash))
			throw(-1);

		memcpy(iv, hash, DIR_IV_LEN);  // all iv's are 16 bytes (DIR_IV_LEN)

	} catch (...) {
		bRet = false;
	}

	return bRet;
}