When protecting a Workbook, a password is optional. The HasProtectionPassword will return true if the Workbook is currently protected (see IsProtected) and a password was specified when it was protected. To protect a Workbook without a password, one may use the Protect method that doesn't take a password.
Target Platforms: Android 4.4+, iOS 8+
Development Environments: Visual Studio 2015+, Visual Studio for Mac Preview, Xamarin for Visual Studio 4.2+