Homomorphic A-codes for Network Coding, by Zhaohui Tang
Authentication codes (A-codes) are a well studied technique to provide unconditionally secure
authentication. An A-code is defined by a map that associates a pair formed by a message and a key
to a tag. A-codes linear in the keys have been studied for application to distributed authentication
schemes. In this paper, we address the dual question, namely the study of A-codes that are linear in the
messages. This is usually an undesired property, except in the context of network coding. Regarding
these A-codes, we derive some lower bounds on security parameters when key space is known. We
also show a lower bound on key size when security parameter values are given (with some special
properties) and construct some codes meeting the bound.
Security and Cryptography Researcher, Safemarket Ltd, Thessaloniki, Greece
Safemarket Ltd., a software development and secure computer services company, seeks one Security or Cryptography specialist for participating on the research project entitled \"Secure Automated E-learning tests and Logic Puzzles\".
Ph.D. in Computer Science with specialization in at least one of the following (or related) areas: Networks/Servers, Computer and Network Security, Applied Cryptography, Computer Systems.
Excellent knowledge on web/application server customization
Strong understanding (server administration) of Linux OS, preferably CentOS or Ubuntu
Experience in Database Security and Cryptography Policies
Certifications: CISSP, CCSP, RHCE, CCNA, MCSA, Linux + Pro, CEH (Certified Ethical Hacker)
MySQL, PHP, Java
Web / SQL Load Balancing
Fluency in English
Game/Application Servers (Glassfish)
Proved experience in network/server management and administration
This a 3-year contract research position (full 36 months) with a salary of about 2100 Euros (gross). The project is Co-financed by the European Union and Greece - Operational Program \'Human Resources Development\' - NSFR 2007-2013 - European Social Fund.
Successful applicant will lead the security group with the role of organising/administrating the whole infrastructure required for supporting secure and fair electronic contests.
Contact: Send a cover letter and a detailed CV to: jobs (at) safemarket.gr
Using Variance to Analyze Visual Cryptography Schemes, by Teng Guo and Feng Liu and ChuanKun Wu and YoungChang Hou
A visual cryptography scheme (VCS) is a secret sharing method, for which the secret can be decoded by human eyes without needing any cryptography knowledge nor any computation. Variance is first introduced by Hou et al. in 2005 and then thoroughly verified by Liu et al. in 2012 to evaluate the visual quality of size invariant VCS. In this paper, we introduce the idea of using variance as an error-detection measurement, by which we find the security defect of Hou et al.\'s multi-pixel encoding method. On the other hand, we find that variance not only effects the visual quality of size invariant VCS, but also effects the
visual quality of VCS. At last, average contrast associated with variance is used as a new criterion to evaluate the visual quality of VCS.