Cryptanalysis of the convex hull click human identification protocol

Ashgar, Hassan Jameel, Li, Shujun, Pieprzyk, Josef, & Wang, Huaxiong (2013) Cryptanalysis of the convex hull click human identification protocol. International Journal of Information Security, 12(2), pp. 83-96.

View at publisher


Recently, a convex hull-based human identification protocol was proposed by Sobrado and Birget, whose steps can be performed by humans without additional aid. The main part of the protocol involves the user mentally forming a convex hull of secret icons in a set of graphical icons and then clicking randomly within this convex hull. While some rudimentary security issues of this protocol have been discussed, a comprehensive security analysis has been lacking. In this paper, we analyze the security of this convex hull-based protocol. In particular, we show two probabilistic attacks that reveal the user’s secret after the observation of only a handful of authentication sessions. These attacks can be efficiently implemented as their time and space complexities are considerably less than brute force attack. We show that while the first attack can be mitigated through appropriately chosen values of system parameters, the second attack succeeds with a non-negligible probability even with large system parameter values that cross the threshold of usability.

Impact and interest:

4 citations in Scopus
Search Google Scholar™
2 citations in Web of Science®

Citation counts are sourced monthly from Scopus and Web of Science® citation databases.

These databases contain citations from different subsets of available publications and different time periods and thus the citation count from each is usually different. Some works are not in either database and no count is displayed. Scopus includes citations from articles published in 1996 onwards, and Web of Science® generally from 1980 onwards.

Citations counts from the Google Scholar™ indexing service can be viewed at the linked Google Scholar™ search.

Full-text downloads:

44 since deposited on 27 Mar 2014
7 in the past twelve months

Full-text downloads displays the total number of times this work’s files (e.g., a PDF) have been downloaded from QUT ePrints as well as the number of downloads in the previous 365 days. The count includes downloads for all files if a work has more than one.

ID Code: 69326
Item Type: Journal Article
Refereed: Yes
Keywords: Human identification protocols, Observer attack, User authentication, Graphical passwords, Human-computer cryptography
DOI: 10.1007/s10207-012-0161-x
ISSN: 1615-5270
Subjects: Australian and New Zealand Standard Research Classification > MATHEMATICAL SCIENCES (010000)
Australian and New Zealand Standard Research Classification > INFORMATION AND COMPUTING SCIENCES (080000)
Divisions: Current > Schools > School of Electrical Engineering & Computer Science
Current > QUT Faculties and Divisions > Science & Engineering Faculty
Copyright Owner: Copyright 2012 Springer-Verlag Berlin Heidelberg
Copyright Statement: The final publication is available at Springer via
Deposited On: 27 Mar 2014 00:15
Last Modified: 18 Apr 2014 14:57

Export: EndNote | Dublin Core | BibTeX

Repository Staff Only: item control page