I want to make sure that not just anyone is posting comments on a site - that is, I want to verify that its a legitimate person commenting. For example, having people write testimonials for a company profile. My initial idea was to be able to post comments with your Twitter handle or LInkedIn profile.
What are some other ways to achieve this without having to moderate?
EDIT: More specifically, what I'm trying to achieve is to figure out the best way for people to write testimonials for someone that they have worked with in the past (i.e. I am a client and I want to write my experience working with X). I don't want users who didn't work with that particular person to write malicious stuff.
From a ux perspective, would the following be obtrusive: Not only must the user must be logged into my website, but they must have a Twitter/LinkedIn or Facebook account connected to their profile in order to write a testimonial. This testimonial would then be sent to the person for their approval.