Rails Device "Fingerprinting"

Question

Is there any way or best practice around device fingerprinting for a rails app? In other words. Given that all cookies are blocked, is there any way, with a relatively good degree of certainty, who the person is before they log in?

My assumption: IPs are unreliable for obvious reasons.

Answer 1

We've setup device fingerprinting in our rails app using ThreatMetrix.com They are sort of expensive, but used by a number of large sites on the web and have built some good technology around this.

I have seen some Jquery open source released for this crop up: https://github.com/carlo/jquery-browser-fingerprint But have not tried it.