Publications by Philippe Janson

Abstract interdomain security assertions: A basis for extra-grid virtual organizations

One significant challenge in building grids between organizations with heterogeneous security systems is the need to express and enforce security policies that specify the users in one organization (the source domain) who are allowed to access the resources in another organization (the target domain). This requires linking the syntax and semantics of security assertions referring to users and their attributes in the source domain to those referring to resources in the target domain. This paper suggests some basic requirements for solving this problem, in particular, an abstract form of interdomain security assertion (IDSA) relying, for instance, on globally meaningful URIs (Uniform Resource Identifiers) to refer to users, resources, and their attributes. This canonical abstract form IDSA is, however, used strictly for assertion mapping purposes. It may - but need not - be visible in any concrete security assertion syntax in any domain. The paper further suggests different scenarios in which URIs for users, resources, and attributes defined in one domain can be mapped to semantically meaningful references - with varying degrees of granularity and accountability - in another domain where they would otherwise be meaningless. © 2004 IBM.

2004

Scalability and flexibility in authentication services: The KryptoKnight approach

Philippe Janson

This paper studies the issues of flexibility and scalability in the context of network security. In particular, it concentrates on authentication and key distribution services suited for a variety of communication paradigms, network environments, and end-devices. We present the design criteria, specification, and step-by-step construction of authentication and key distribution services based on experience in the KryptoKnight project. The central goal of the KryptoKnight project was the construction of basic network security functions in a minimal, flexible (thus, versatile) and scalable manner. Protocol minimality (in terms of resource usage) and flexibility are not merely theoretical goals; they have clear advantages in environments where computational resources are limited and connectivity is restricted. KryptoKnight was aimed at such environments: small and anemic wireless devices, simple network and data-link entities, embedded micro-devices and other special-purpose communication equipment and configurations. Furthermore, scalability of protocols makes their deployment possible in the presence of rapid network growth and inter-domain communication.

1997

State of the art in electronic payment systems

Philippe Janson

The exchange of goods conducted face-to-face between two parties dates back to before the beginning of recorded history. Traditional means of payment have always had security problems, but now electronic payments retain the same drawbacks and add some risks. Unlike paper, digital `documents' can be copied perfectly and arbitrarily often; digital signatures can be produced by anybody who knows the secret cryptographic key; a buyer's name can be associated with every payment, eliminating the anonymity of cash. Without new security measures, wide-spread electronic commerce is not viable. On the other hand, properly designed electronic payment systems can actually provide better security than traditional means of payments, in addition to flexibility. This article provides an overview of electronic payment systems, focusing on issues related to security.

1997

Robust and secure password and key change method

Philippe Janson

This paper discusses issues and idiosyncrasies associated with changing passwords and keys in distributed computer systems. Current approaches are often complicated and fail to provide the desired level of security and fault tolerance. A novel and very simple approach to changing passwords/keys is presented and analyzed. It provides a means for human users and service programs to change passwords and keys in a robust and secure fashion.

1996

KryptoKnight family of light-weight protocols for authentication and key distribution

Philippe Janson

An essential function for achieving security in computer networks is reliable authentication of communicating parties and network components. Such authentication typically relies on exchanges of cryptographic messages between the involved parties, which in turn implies that these parties be able to acquire shared secret keys or certified public keys. Provision of authentication and key distribution functions in the primitive and resource-constrained environments of low-function networking mechanisms, portable, or wireless devices presents challenges in terms of resource usage, system management, ease of use, efficiency, and flexibility that are beyond the capabilities of previous designs such as Kerberos or X.509. This paper presents a family of light-weight authentication and key distribution protocols suitable for use in the low layers of network architectures. All the protocols are built around a common two-way authentication protocol. The paper argues that key distribution may require substantially different approaches in different network environments and shows that the proposed family of protocols offers a flexible palette of compatible solutions addressing many different networking scenarios. The mechanisms are minimal in cryptographic processing and message size, yet they are strong enough to meet the needs of secure key distribution for network entity authentication. The protocols presented have been implemented as part of a comprehensive security subsystem prototype called KryptoKnight, whose software and implementation aspects are discussed in [16], and which is the basis for the recently announced IBM Network Security Program product.

1995

Secure and minimal protocols for authenticated key distribution

Philippe Janson

The problem of secure key distribution has been the subject of much attention in recent years. This paper describes a novel method for authenticated key distribution in the distributed systems environment. In particular, a braiding technique for key distribution is introduced. The underlying protocols are extremely compact in both the number of messages and message sizes, which facilitates their application at any layer (at lower layers, in particular) in the protocol hierarchy. Furthermore, the protocols are shown to be resistant to a wide range of interleaving attacks. All this is achieved with minimal computational requirements, and without the necessity of using traditional encryption (a strong one-way function suffices).

1995

The extensive use of open networks and distributed system poses serious threats to the security of end-to-end communications and network components themselves. A necessary foundation for securing a network is the ability to reliably authenticate communication partners and other network entities. One-way password-based authentication techniques are not sufficient to cope with the issues at hand. Modern designs rely on two-way cryptographic authentication protocols. However, most existing designs suffer from one or more limitations: they require synchronization of local clocks, they are subject to export restrictions because of the way they use cryptographic functions. they are not amenable to use in lower layers of network protocols because of the size and complexity of messages they use, etc. Designing suitable cryptographic protocols that cater to large and dynamic network communities but do not suffer from the above problems presents substantial challenges in terms of ease of use, efficiency, flexibility, and above all security. This paper discusses the above challenges; shows how a few simple protocols, including one proposed by ISO, can easily be broken; and derives a series of desirable properties that authentication protocols should exhibit to meet the requirements of future large and dynamic network communities. Then the paper describes a methodology that was developed to systematically build and test the security of a family of cryptographic two-way authentication protocols that are as simple as possible yet resistant to a wide class of attacks, efficient, easy to implement and use, and amenable to many different networking environments. It also discusses several concrete examples of protocols of that family that presents various advantages in specific distributed system scenarios.

1993

Architectural directions for opening IBM networks: The case of OSI

Philippe Janson

The authors discuss the results of a research project that developed an architectural framework for integrating non-IBM network architectures with the reference model and node structures of IBM's System Network Architecture (SNA). The unique features of the selected integration approach allow multiple protocol stacks to coexist and interoperate within the same computer, to share access to common physical network ports, links, and switching nodes, and to be accessed and managed through homogeneous interfaces. The architectural framework was developed for the specific purpose of integrating the open systems interconnection (OSI) reference model to that of SNA, but its basic philosophy and key aspects turn out to be generally applicable to the integration of other network technologies as well, e.g. TCP/IP or NETBIOS.

1991

Heterogeneity and OSI

Philippe Janson

A review is presented of the different aspects of heterogeneity that need to be resolved to achieve global interoperability, and specifically, to provide global transport service. It concentrates on the problems of interconnecting computer networks and systems that use different protocols, either different subsets of OSI (Open Systems Interconnection) standards or OSI and non-OSI protocols. The issues of protocol conversion are discussed, and integrated naming, addressing, and directory mechanisms for interconnecting OSI and non-OSI domains are outlined. More subtle aspects of interoperability are examined for the case of the OSI transport protocol class 4 in mixed LAN/WAN (local-area-network/wide-area network) environments.

1990

Interconnecting heterogeneous networks to osi with a global name scheme and gateway address mapping.

Philippe Janson

The ongoing development of the OSI standards for computer communication prompts existing networks to provide OSI inteconnectivity. Achieving this requires two mechanisms: a global scheme to name applications, and specific solutions to provide internetwork addressability between applications. The problem of identification of remote resources across between two networks is considered. A solution is presented for the case of the interconnection of OSI and of a generic non-OSI network architecture. The OSI model is presented first, then an integration strategy is developed, both for naming and addressing. An internetwork directory service instrumental to such an integration is introduced and developed in some detail.

1988