Chris J. Mitchell

Bio: Chris J. Mitchell is an academic researcher from Royal Holloway, University of London. The author has contributed to research in topics: Authentication & Cryptography. The author has an hindex of 48, co-authored 397 publications receiving 10982 citations. Previous affiliations of Chris J. Mitchell include Johns Hopkins University & University of Portland.

Building general purpose security services on trusted computing

Abstract: The Generic Authentication Architecture (GAA) is a standardised extension to the mobile telephony security infrastructures (including the Universal Mobile Telecommunications System (UMTS) authentication infrastructure) that supports the provision of generic security services to network applications. In this paper we propose one possible means for extending the widespread Trusted Computing security infrastructure using a GAA-like framework. This enables an existing security infrastructure to be used as the basis of a general-purpose authenticated key establishment service in a simple and uniform way, and also provides an opportunity for trusted computing aware third parties to provide novel security services. We also discuss trust issues and possible applications of GAA services.

The Saeed-Liu-Tian-Gao-Li authenticated key agreement protocol is insecure.

Abstract: A recently proposed authenticated key agreement protocol is shown to be insecure. In particular, one of the two parties is not authenticated, allowing an active man in the middle opponent to replay old messages. The protocol is essentially an authenticated Diffie-Hellman key agreement scheme, and the lack of authentication allows an attacker to replay old messages and have them accepted. Moreover, if the ephemeral key used to compute a protocol message is ever compromised, then the key established using the replayed message will also be compromised. Fixing the problem is simple - there are many provably secure and standardised protocols which are just as efficient as the flawed scheme.

Security issues in a group key establishment protocol

Abstract: Major shortcomings in a recently published group key establishment protocol are described. These shortcomings are sufficiently serious that the protocol should not be used.

Key minimal authentication system for unconditional secrecy

Abstract: This paper is concerned with cryptosystems offering unconditional secrecy. For those perfect secrecy systems which involve using key just once, the theory is well established since Shannon’s works; however, this is not the case for those systems which involve using a key several times. This paper intends to take a rigorous approach to the definition of such systems. We use the basic model for a security code developped by Simmons, initially for unconditional authentication. We consider the definition of perfect L-fold secrecy given by Stinson and used by De Soete and others. We consider other definitions: Ordered Perfect L-fold secrety and Massey’s Perfect L-fold secrecy, and attempt to classify them. Lower bounds are given for the number of keys in such perfect systems, and characterisation of systems meeting these lower bounds are obtained. The last part of the paper is concerned with discussing examples of key minimal systems providing unconditional secrecy.

How not to secure wireless sensor networks: A plethora of insecure polynomial-based key pre-distribution schemes

Abstract: Three closely-related polynomial-based group key pre-distribution schemes have recently been proposed, aimed specifically at wireless sensor networks. The schemes enable any subset of a predefined set of sensor nodes to establish a shared secret key without any communications overhead. It is claimed that these schemes are both secure and lightweight, i.e. making them particularly appropriate for network scenarios where nodes have limited computational and storage capabilities. Further papers have built on these schemes, e.g. to propose secure routing protocols for wireless sensor networks. Unfortunately, as we show in this paper, all three schemes are completely insecure; whilst the details of their operation varies, they share common weaknesses. In every case we show that an attacker equipped with the information built into at most two sensor nodes can compute group keys for all possible groups of which the attacked nodes are not a member, which breaks a fundamental design objective. The attacks can also be achieved by an attacker armed with the information from a single node together with a single group key to which this sensor node is not entitled. Repairing the schemes appears difficult, if not impossible. The existence of major flaws is not surprising given the complete absence of any rigorous proofs of security for the proposed schemes. A further recent paper proposes a group membership authentication and key establishment scheme based on one of the three key pre-distribution schemes analysed here; as we demonstrate, this scheme is also insecure, as the attack we describe on the corresponding pre-distribution scheme enables the authentication process to be compromised.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

Handbook of Applied Cryptography

Abstract: From the Publisher: A valuable reference for the novice as well as for the expert who needs a wider scope of coverage within the area of cryptography, this book provides easy and rapid access of information and includes more than 200 algorithms and protocols; more than 200 tables and figures; more than 1,000 numbered definitions, facts, examples, notes, and remarks; and over 1,250 significant references, including brief comments on each paper.

Tissue-based map of the human proteome

Abstract: Resolving the molecular details of proteome variation in the different tissues and organs of the human body will greatly increase our knowledge of human biology and disease. Here, we present a map of the human tissue proteome based on an integrated omics approach that involves quantitative transcriptomics at the tissue and organ level, combined with tissue microarray-based immunohistochemistry, to achieve spatial localization of proteins down to the single-cell level. Our tissue-based analysis detected more than 90% of the putative protein-coding genes. We used this approach to explore the human secretome, the membrane proteome, the druggable proteome, the cancer proteome, and the metabolic functions in 32 different tissues and organs. All the data are integrated in an interactive Web-based database that allows exploration of individual proteins, as well as navigation of global expression patterns, in all major tissues and organs in the human body.

Differential Power Analysis

Abstract: Cryptosystem designers frequently assume that secrets will be manipulated in closed, reliable computing environments. Unfortunately, actual computers and microchips leak information about the operations they process. This paper examines specific methods for analyzing power consumption measurements to find secret keys from tamper resistant devices. We also discuss approaches for building cryptosystems that can operate securely in existing hardware that leaks information.