Contains different system attack scenarios

All shared secret or shared control schemes devised thus far are autocratic in the sense that they depend in their realization on the exsistance of a single party-which may be either an individual or a device-that is unconditionally trusted by all the participants in the scheme [5,6]. The function of this trusted party is to first choose the secret (piece of information) and then to construct and distribute in secret to each of the participants the private pieces of information which are their shares in the shared secret or control scheme. The private pieces of information are constructed in such a way that any authorized concurrence (subset) of the participants will jointly have sufficient information about the secret to reconstruct it while no unauthorized collection of them will be able to do so. For many applications, though, there is no one who is trusted by anyone else. In the absence of a trusted party or authority, no one can be trusted to know the secret and hence-until now-it has appeared to be impossible to construct and distribute the private pieces of information needed to realize a shared control scheme. It is worth noting that in commercial and/or international applications, this situation is more nearly the norm than then exception.

The paper presents a comparative assessment of the suitability of exisitng access control models for use in web-based applciations.

This paper describes KryptoKnight, an authentication and key distribution system that provides facilities for secure communication in any type of network environment. KryptoKnight was designed with the goal of providing network secuity services with a high degree of compactness and flexibility. Message compactness of KryptoKnight’s protocols allows it to secure the communication protocols at any layer, without requiring any major protocol augmentations in order to accommodate security-related information. Moreover, since KryptoKnight avoids the use of bulk encryption it is easily exportable. Owing to its architechtural flexibility, KryptoKnight functions at both endpoints oc communication can perform different security tasks depending on the network configuration. These and other novel features make KryptoKnight an attractive solution for provideing security services to existing applications irrespective of the protocol layer, network configuration of communication paradigm.

We describe a theory of authentication and a system that implements it. Our theory is bases on the notion of pricipal and a ‘speak for’ relation between principals. A simple principal either has a name or is a communication channel; a compound principal can express an adobted role or delegated authority. The theory shows how to reason about a principal’s authority by deducing the other principals the other principals that it can speak for; authenticating a channel is one important application. We use the theory to explain many existing and proposed security mechanisms. In particular, we describe the system we have built. It passes principals efficiently as arguments or results of remote procedure calls, and it handles public and shared key encryption, name lookup in a large name space, groups of principals, program loading, delegation, access control, and revocation.

We describe a design for security in a distributed system and its implementation. In our design, applications gain access to security services through a narrow interface. This interface provides a notion of identity that includes simple principals, groups, roles, and delegations. A new operating system component manages principals, credentials, and secure channels. It checks credentials according to the formal rules of a logic of authentication. Our implementationis efficient enough to support a substantial user comminuity.

Questions of belief are essential in analyzing protocols for the authentication of principals in distributed computing systems. In this paper we motivate, set out, and exemplify a logic specifically designed for this analysis; we show how various protocols differ subtly with respect to the required initial assumptions of the participants and thier final beliefs. Our formalism has enabled us to isolate and express these differences with a precision that was not previously possible. It has drawn attention to features of protocols of which we and thier authors were previously unaware, and allowed us to suggest improvements to the protocols. The reasoning about some protocols has been mechanically verified. This paper starts with an informal account of the problem, goes on to explain the formalism to be used, and gives examples of its application to protocols from the literature, both with shared-key cryptography and with public-key cryptography. Some of the examples are chosen because of their practical importance, while others serve to illustrate subtle points of the logic and to explain how we use it. We discuss extensions of the logic motivated by actual practice - for example, in order to account for the use of hash functions in signatures The final sections contain a formal semantics of the logic and some conclusions.

We propose a new distributed security infrastucture, called SDSI (pronounced “Sudsy”). SDSI combines a simple public-key infrastructure design with a means of defining groups and issuing group-membership certificates. SDSI’s groups provides simple, clear terminology for defining access-control lists and security policies. SDSI’s design emphasizes linked local name spaces rather than a hierarchical global name space.

Our motivation is the notion of “time-released crypto”, where the goal is to encrypt a message so that it can not be decrypted by anyone, not even the sender, until a pre- determined amount of time has passed. The goal is to “send information into the future”. This problem was first discussed by Timothy May.

Key management schemes implemented in tamper-proof secure modules are an essential feature of cryptographic systems applied to networks. Such systems must have sufficient functionality to meet the demands of users but at the same time they must not be capable of successful manipulation aimed at an attack on the system. This paper describes a PROLOG program which seeks security flaws in models of such schemes, and hence enhances the assurance provided by the designer on the security of the system. The PROLOG program extensively searches for potential attacks in a simple rule-based modle of of the system; it is suggested that this program is capable of extended operations in other areas when security or safety flaws are to be investigated.

A model of a real-time intrusion-detection expert system capable of detecting break-ins, penetrations, and other forms of computer abuse is described. The model is based on the hypothesis that security violations can be detected by monitoring a system’s audit records for abnormal patterns of system usage. The model includes profiles for representing the behavior of subjects with respect to objects in terms of metrics and statistical models, and rules for acquiring knowledge about the behavior from audit records and for detecting anomalous behavior. The model is independent of any particular system, application environment, system vulnerability, or type of intrusion, thereby providing a framework for a general-purpose intrusion detection expert system.

Recently, an information security professional at a Fortune 500 corporation called the CSI Hotline and asked, “Should I be thinking about electronic commerce?” What should I be concerned with?” The short answer to the first question is “Yes”, the short answer to the second question is “Plenty”. Here’s a little background to get you up to speed. In “Industry in Focus”, Mack Hicks, Vice-President of Bank of America (San Francisco) offers further insight on the future of secure electronic commerce.

In 1990 Rivest introduced the hash function MD4. Two years later RIPEMD, a European proposal, was designed as a stronger mode of MD4. Recently we have found an attack against two of three rounds of RIPEMD. As we shall show in the present note, the methods developed to attack RIPEMD can be modified and supplemented such that it is possible to break the full MD4, while previously only partial attacks were known. An implementation of our attack allows to find collisions for MD4 in less than a minute on a PC.

Computer break-ins are getting more common every day. Log files and even program binaries are changed, making it very hard for the system administratiors to assess the damage and track down the intruders. This paper describes the “modus operandi” of hackers based on mulitiple hacking attempts that occurred during this year at some department computers. Special attention is paid to the methods they use to break into computer systems and what they do once they are in.