Very important observation for advocates of two-factor authentication: cellular network and SMS services in some parts of the world are not trustworthy. It's much better to use single strong password versus weak password + numeric codes delivered by SMS which can be monitored/changed on the fly by an adversary.
The key is to impersonate enough phones (tunneling over a trusted subset of the network) or use a network that won't identify the endpoints. The former is much easier.
Would you know who wrote it if I didn't link to it?
Also, pastes are not done via ssl connections, so anybody between you and pastie knows what's in that paste, and what IP created it.
Depending on how you send that link, that messaging provider knows (for example sending it via Skype, Microsoft knows).
And thence does anybody with the legal capability of subponeaing data from any of those services.
If the sender can edit a previous paste, they can agree on a URL, but I didn't see how to do that.