CHURNs : freshness assurance for humans

Radke, Kenneth, Boyd, Colin, Gonzalez Nieto, Juan M., & Bartlett, Harry (2015) CHURNs : freshness assurance for humans. The Computer Journal, 58(10), pp. 2404-2425.


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We present CHURNs, a method for providing freshness and authentication assurances to human users. In computer-to-computer protocols, it has long been accepted that assurances of freshness such as random nonces are required to prevent replay attacks. Typically, no such assurance of freshness is presented to a human in a human-and-computer protocol. A Computer–HUman Recognisable Nonce (CHURN) is a computer-aided random sequence that the human has a measure of control over and input into. Our approach overcomes limitations such as ‘humans cannot do random’ and that humans will follow the easiest path. Our findings show that CHURNs are significantly more random than values produced by unaided humans; that humans may be used as a second source of randomness, and we give measurements as to how much randomness can be gained from humans using our approach; and that our CHURN-generator makes the user feel more in control, thus removing the need for complete trust in devices and underlying protocols. We give an example of how a CHURN may be used to provide assurances of freshness and authentication for humans in a widely used protocol.

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ID Code: 75851
Item Type: Journal Article
Refereed: Yes
Keywords: Human, Protocols, Internet, Web-based security, CHURNS
DOI: 10.1093/comjnl/bxu073
ISSN: 0010-4620
Divisions: Current > QUT Faculties and Divisions > Science & Engineering Faculty
Copyright Owner: Copyright 2014 The British Computer Society
Deposited On: 01 Sep 2014 22:28
Last Modified: 23 Jun 2017 16:50

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