It's exactly why marshmallow is changing the permissions model. All of those permissions are necessary if you want an app that:

* can show a contact's name on a message they sent you * can save public keys and access them * can send/receive messages with multimedia * can uniquely identify your device and you as a user (to generate your private key with unique primitives)

Off the top of my head iIdon't know why it asks for calendar permission, but we could inspect the source...

The point is, if you're trying to make a mass market app, you have to offer competitive features... And that requires a lot of permissions.