Communications of the ACM (CACM for short, not the best sounding acronym around) is the ACM’s flagship magazine. Started in 1957, CACM is handy for keeping up to date on current research being carried out across all topics of computer science and realworld applications. CACM has had an illustrious past with many influential pieces of work and debates started within its pages. These include Hoare’s presentation of the Quicksort algorithm; Rivest, Shamir and Adleman’s description of the first publickey cryptosystem RSA; and Dijkstra’s famous letter against the use of GOTO. In addition to the print edition, which is released monthly, there is a fantastic website (http://cacm.acm. org/) that showcases not only the most recent edition but all previous CACM articles as well, readable online as well as downloadable as a PDF. In addition, the website lets you browse for articles by subject, a handy feature if you want to focus on a particular topic. CACM is really essential reading. Pretty much guaranteed to contain content that is interesting to anyone, it keeps tabs on the latest in computer science. It is a valuable asset for us students, who tend to delve deep into a particular area of CS and forget everything that is happening around us. — Daniel Gooch U ndergraduate research is like a box of chocolates: You never know what kind of project you will get. That being said, there are still a few things you should know to get the most out of the experience.

Communications of the ACM

An important open problem in the area of Traitor Tracing is designing a scheme with constant expansion of the size of keys (users' keys and the encryption key) and of the size of ciphertexts with respect to the size of the plaintext. This problem is known from the introduction of Traitor Tracing by Chor, Fiat and Naor. We refer to such schemes as traitor tracing with constant transmission rate. Here we present a general methodology and two protocol constructions that result in the first two public-key traitor tracing schemes with constant transmission rate in settings where plaintexts can be calibrated to be sufficiently large. Our starting point is the notion of copyrighted function which was presented by Naccache, Shamir and Stern. We first solve the open problem of discrete-log-based and public-key-based copyrighted function. Then, we observe the simple yet crucial relation between (public-key) copyrighted encryption and (public-key) traitor tracing, which we exploit by introducing a generic design paradigm for designing constant transmission rate traitor tracing schemes based on copyrighted encryption functions. Our first scheme achieves the same expansion efficiency as regular ElGamal encryption. The second scheme introduces only a slightly larger (constant) overhead, however, it additionally achieves efficient black-box traitor tracing (against any pirate construction).

Traitor Tracing with constant transmission rate

An efficient biometrics-based remote user authentication scheme using smart cards

The authentication scheme is an important cryptographic mechanism, through which two communication parties could authenticate each other in the open network environment To satisfy the requirement of practical applications, many authentication schemes using passwords and smart cards have been proposed However, passwords might be divulged or forgotten, and smart cards might be shared, lost, or stolen In contrast, biometric methods, such as fingerprints or iris scans, have no such drawbacks Therefore, biometrics-based authentication schemes gain wide attention In this paper, we propose a biometrics-based authentication scheme for multiserver environment using elliptic curve cryptography To the best of our knowledge, the proposed scheme is the first truly three-factor authenticated scheme for multiserver environment We also demonstrate the completeness of the proposed scheme using the Burrows–Abadi–Needham logic

Robust Biometrics-Based Authentication Scheme for Multiserver Environment

In this paper, a comprehensive survey of authentication protocols for Internet of Things (IoT) is presented. Specifically more than forty authentication protocols developed for or applied in the context of the IoT are selected and examined in detail. These protocols are categorized based on the target environment: (1) Machine to Machine Communications (M2M), (2) Internet of Vehicles (IoV), (3) Internet of Energy (IoE), and (4) Internet of Sensors (IoS). Threat models, countermeasures, and formal security verification techniques used in authentication protocols for the IoT are presented. In addition a taxonomy and comparison of authentication protocols that are developed for the IoT in terms of network model, specific security goals, main processes, computation complexity, and communication overhead are provided. Based on the current survey, open issues are identified and future research directions are proposed.

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Authentication Protocols for Internet of Things: A Comprehensive Survey

We describe an identity based signature scheme that uses biometric information to construct the public key. Such a scheme would be beneficial in many repudiation situations for example a legal dispute over whether a contract had been signed or not by a user. A biometric reading provided by the alleged signer would be enough to verify the signature. We make use of fuzzy extractors to generate a key string from a variable biometric measurement. We use this biometric based key string and an elliptic curve point embedding technique to create the public key and corresponding private key. We then make use of a pairing based signature scheme to perform signing and verification with these keys. We discuss security issues of the system and suggest countermeasures to attack. Finally we describe a working biometric signature scheme developed in part by reusing components in an existing Java Identity Based Encryption implementation.

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A Biometric Identity Based Signature Scheme

We describe an Identity Based Encryption (IBE) cryptosystem based on a scheme presented by Boneh and Franklin [3]. We implement the abstract mathematical concepts underlying this system. We reuse an existing Elliptic curve arithmetic API, [4] to reduce the development time of the IBE system. We present a Java Cryptographic Architecture (JCA) integrated implementation of IBE that will allow Java developers to easily take advantage of this new encryption system and thus eliminate some of the most serious practical problems associated with existing public key infrastructure systems. The JCA implementation facilitates the hiding of all the complicated mathematical details of the system and further demonstrates the utility of Java as security development language.

An Identity Based Encryption system

Ad hoc wireless networks offer anytime-anywhere networking services for infrastructure-free communication over the shared wireless medium. The proliferation of portable devices and ad hoc networks have led to the need for security services. This is illustrated daily in the media with reports of wireless network vulnerabilities. In this setting, secure group key agreement and efficient group key management are considered challenging tasks from both an algorithmic and computational point of view due to resource constraint in wireless networks. In this article, we present two dynamically efficient authenticated group key agreement protocols by reflecting ad hoc networks in a topology composed by a set of clusters. We analyse the complexity of the schemes and differentiate between the two approaches based on performance in a wireless setting. The proposed protocols avoid the use of a trusted third party (TTP) or a central authority, eliminating a single point attack. They allow easy addition and removal of nodes, and achieve better performance in comparison with the existing cluster based key agreements. Additionally, our proposed schemes are supported by sound security analysis in formal security models under standard cryptographic assumptions.

Secure and Efficient Group Key Agreements for Cluster Based Networks

Current Digital Rights Management (DRM) systems support only two-party systems, involving the package server and purchaser. However, for a scalable business model of transacting digital assets, a multi-party DRM system is often necessary which involves more than one distributors, who can promote and distribute the content in regions unknown to the package server. We propose a key management scheme for a DRM system that involves more than one distributors with the DRM client's flexibility of choosing a distributor according to his own preference. For instance, a mobile DRM client may contact to a distribution server who is nearest to him by location or who offers promotions/discounts on the price or offers more commissions. In our scheme, the package server does not trust the distribution servers or the license server. The encrypted digital content sent by a package server can only be decrypted by the DRM client who has a valid license and is protected from attacks by other parties/servers in the system. Moreover, we use Identity-Based Encryption (IBE) that incurs less computation cost and storage as certificate managements are not necessary and certificate verifications are no longer needed. These features make our DRM system suitable for more effective business models/applications with the flexibility in deciding a wide range of business strategies as compared to the existing works.

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Key management in multi-distributor based DRM system with mobile clients using IBE

A fundamental concern of any secure group communication system is that of key management. Wireless environments create new key management problems and requirements to solve these problems. One such core requirement in these emerging networks is that of self-healing. In systems where users can be offline and miss updates self healing allows a user to recover lost keys and get back into the secure communication without putting extra burden on the group manager. Clearly self healing must be only available to authorized users and this creates more challenges in that we must ensure unauthorized or revoked users cannot, themselves or by means of collusion, avail of self healing. To this end we enhance the one-way key chain based self-healing key distribution of Dutta et al. by introducing a collusion resistance property between the revoked users and the newly joined users. Our scheme is based on the concept of access polynomials. These can be loosely thought of as white lists of authorized users as opposed to the more widely used revocation polynomials or black lists of revoked users. We also allow each user a pre-arranged life cycle distributed by the group manager. Our scheme provides better efficiency in terms of storage, and the communication and computation costs do not increase as the number of sessions grows as compared to most current schemes. We analyze our scheme in an appropriate security model and prove that the proposed scheme is computationally secure and not only achieving forward and backward secrecy, but also resisting collusion between the new joined users and the revoked users. Unlike most existing schemes the new scheme allows temporary revocation. Also unlike existing schemes, our construction does not collapse if the number of revoked users crosses a threshold value. This feature increases resilience against revocation based denial of service (DOS) attacks and thus improves availability of communication channel.

Tom Dowling

Papers

A Biometric Identity Based Signature Scheme

An Identity Based Encryption system

Secure and Efficient Group Key Agreements for Cluster Based Networks

Key management in multi-distributor based DRM system with mobile clients using IBE

Enhanced Access Polynomial Based Self-healing Key Distribution