11332993
Fine-Grained and Scalable Approaches for Message Integrity
When we have multiple users compiling a single message, including shared contents, metadata, policy, and so on, the integrity of the contents created by individual users needs to be maintained in an effective manner. There is an urgent need for new mechanisms in a trusted content-sharing environment to support multiple signers for the same message, which can be dynamically updated with autonomous protection and maintenance mechanisms. In our previous work we identified and compared three different binding mechanisms including monolithic, autonomous, and chained binding mechanisms, using digital signatures. The original work was designed and implemented for digital certificates. In this paper we apply those schemes with extension to the organization-to-organization messaging services that require effective integrity verification and tracking mechanisms at the user-level in the receiving organization in a scalable manner with fine granularity. We implement our ideas in the Java remote method invocation (RMI) platform and discuss the trade-offs of the signature schemes based on our experimental results
8509534
RBAC on the Web by smart certificates
We have described in another paper how to develop and use smart certi cates by extending X.509 with several sophisticated features for secure attribute services on the Web. In this paper, we describe an implementation of RBAC (Role-Based Access Control) with role hierarchies on the Web as one possible application of smart certi cates. To support RBAC, we issued smart certi cates which hold the subjects' role information and con gured a Web server to use the role information in the certi cate instead of identities for its access control mechanism. Since the subjects' role information is provided integrity, the Web server can trust the role information after authentication and certi cate veri cation by SSL, and uses it for role-based access control. To maintain compatibility with existing technologies, such as SSL, we used a bundled (containing the subject's identity and role information) smart certi cate in the user-pull model.
13486405
Static vs. dynamic recovery models for survivable distributed systems
The need for survivability is more pressing for mission-critical systems, especially when they are integrated with other COTS products or services. As information systems became more complex and the interdependence of these systems became higher, the survivability picture became more complicated. In this paper, we introduce two basic models with respect to static and dynamic models, where each model has restart and continue modes. We describe each approach and compare the trade-offs in terms of simplicity, resource efficiency, adaptation, service downtime, immunization, and robustness. Later, we introduce a hybrid model by combining these two basic models. Our approaches are transparent to the client side and can be applied to existing distributed systems by extending the server side with the components necessary for the schemes.
42838112
Trusted Identity and Session Management Using Secure Cookies
The concept of federated identity management is increasingly coming to use in order to bring Service Providers closer to customers. Users are being provided an enriched experience while carrying out business on the Web at reduced overhead and improved customer service. The idea of maintaining a single profile and gaining access to multiple services has been accepted well by the customers. However, the benefits of breaking through just one set of credentials to gain access to multiple services has made the concept of Federated Identity Management of high interest to malicious users. In this paper, we analyze the structure of a generic Federated Identity Management System and explore the .NET Passport framework in depth. We explore the current security mechanisms adopted by the .NET Passport and identify potential security weaknesses. We then propose our new approaches to enhance the security services in .NET Passport by using Secure Cookies. Our approaches are transparent to and compatible with the current .NET Passport server. Finally, we prove the feasibility by implementing our ideas in a real system.
14631475
RBAC on the Web by Secure Cookies
Current approaches to access control on Web servers do not scale to enterprise-wide systems, since they are mostly based on individual users. Therefore, we were motivated by the need to manage and enforce the strong access control technology of RBAC in large-scale Web environments. Cookies can be used to support RBAC on the Web, holding users’ role information. However, it is insecure to store and transmit sensitive information in cookies. Cookies are stored and transmitted in clear text, which is readable and easily forged. In this paper, we describe an implementation of Role-Based Access Control with role hierarchies on the Web by secure cookies. Since a user’s role information is contained in a set of secure cookies and transmitted to the corresponding Web servers, these servers can trust the role information in the cookies after cookie-verification procedures and use it for role-based access control. In our implementation, we used CGI scripts and PGP (Pretty Good Privacy) to provide security services to secure cookies. The approach is transparent to users and applicable to existing Web servers and browsers.
7753152
Countering Insider Threats in Personal Devices
The information age is a time when organizations are networked back and forth with multiple wires, different communication channels, many sophisticated information systems, and most importantly through the almighty Internet. This project focuses on responses that are most beneficial to organizations in regards to the internal threats. Mainly, it addresses the issues connected to the broad use of laptops, desktops, and other personal devices such as flash drives. During research there were thought different ways of mitigating the issue of insider threats. The result of this analysis is the Diamond Theory. It ties four methods of increasing the security of personal devices: software design, information retrieval, detection technology design and information policy design. All four corners of the diamond are represented by four different techniques that increase the security of personal devices and thus the defense against insider threats. These techniques are described as theoretical premises that shall be fulfilled in order to have the security raised to the maximum. Additionally, these methods are interdependent of each other and must work together to meet the overall goal of the theory.
14990532
Weaving Aspects into Real-Time Operating System Design Using Object-Oriented Model Transformation
Despite of the proliferation of object-oriented and component technology, their application to real-time operating systems (RTOS) has been limited since most design concerns in RTOSes crosscut software components and these are critical to deliver required performance and functionality. Aspect-Oriented Programming (AOP) is a very effective means to solve the crosscutting problem. However, we have observed the following limitations of the current AOP framework: (1) the current text-based AOP languages cannot clearly show how aspects are weaved together, (2) their granularity is too coarse to capture all aspects in an RTOS, (3) it is difficult to control the weaving process, since aspect weavers are usually hard-coded. In this paper, we propose a new AOP framework that provides (1) a graphical aspect programming environment that visualizes aspects, crosscutting classes, and method structures, (2) a new aspect model that supports a sub-method level granularity where an aspect is defined as a set of classes, and (3) an aspect weaving process specified by an object-oriented meta-model transformation. Since our aspect-oriented programming framework improves the expressiveness of the crosscutting concerns of RTOSes and automates aspect weaver generation, it can enhance RTOS customization.
799734
Efficient multicast packet authentication using signature amortization
We describe a novel method for authenticating multicast packets that is robust against packet loss. Our main focus is to minimize the size of the communication overhead required to authenticate the packets. Our approach is to encode the hash values and the signatures with Rabin's Information Dispersal Algorithm (IDA) to construct an authentication scheme that amortizes a single signature operation over multiple packets. This strategy is especially efficient in terms of space overhead, because just the essential elements needed for authentication (i.e., one hash per packet and one signature per group of packets) are used in conjunction with an erasure code that is space optimal. To evaluate the performance of our scheme, we compare our technique with four other previously proposed schemes using analytical and empirical results. Two different bursty loss models are considered in the analyses.
15702195
OCR in a Hierarchical Feature Space
This paper describes hierarchical OCR, a character recognition methodology that achieves high speed and accuracy by using a multiresolution and hierarchical feature space. Features at different resolutions, from coarse to fine-grained, are implemented by means of a recursive classification scheme. Typically, recognizers have to balance the use of features at many resolutions (which yields a high accuracy), with the burden on computational resources in terms of storage space and processing time. We present in this paper, a method that adaptively determines the degree of resolution necessary in order to classify an input pattern. This leads to optimal use of computational resources. The hierarchical OCR dynamically adapts to factors such as the quality of the input pattern, its intrinsic similarities and differences from patterns of other classes it is being compared against, and the processing time available. Furthermore, the finer resolution is accorded to only certain "zones" of the input pattern which are deemed important given the classes that are being discriminated. Experimental results support the methodology presented. When tested on standard NIST data sets, the hierarchical OCR proves to be 300 times faster than a traditional K-nearest-neighbor classification method, and 10 times taster than a neural network method. The comparison uses the same feature set for all methods. Recognition rate of about 96 percent is achieved by the hierarchical OCR. This is at par with the other two traditional methods.
28122333
Using a Hash-Based Method with Transaction Trimming for Mining Association Rules
We examine the issue of mining association rules among items in a large database of sales transactions. Mining association rules means that, given a database of sales transactions, to discover all associations among items such that the presence of some items in a transaction will imply the presence of other items in the same transaction. The mining of association rules can be mapped into the problem of discovering large itemsets where a large itemset is a group of items that appear in a sufficient number of transactions. The problem of discovering large itemsets can be solved by constructing a candidate set of itemsets first, and then, identifying, within this candidate set, these itemsets that meet the large itemset requirement. Generally, this is done iteratively for each large k-itemset in increasing order of k, where a large k-itemset is a large itemset with k items. To determine large itemsets from a huge number of candidate sets in early iterations is usually the dominating factor for the overall data mining performance. To address this issue, we develop an effective algorithm for the candidate set generation. It is a hash-based algorithm and is especially effective for the generation of a candidate set for large 2-itemsets. Explicitly, the number of candidate 2-itemsets generated by the proposed algorithm is, in orders of magnitude, smaller than that by previous methods, thus resolving the performance bottleneck. Note that the generation of smaller candidate sets enables us to effectively trim the transaction database size at a much earlier stage of the iterations, thereby reducing the computational cost for later iterations significantly. The advantage of the proposed algorithm also provides us the opportunity of reducing the amount of disk I/O required. An extensive simulation study is conducted to evaluate performance of the proposed algorithm.
15933972
A logical specification for usage control
Recently presented usage control (UCON) has been considered as the next generation access control model with distinguishing properties of decision continuity and attribute mutability. Ausage control decision is determined by combining authorizations, obligations, and conditions, presented as UCONABC core models by Park and Sandhu. Based on these core aspects, we develop afirst-order logic specification of UCON with Lamport's temporallogic of actions (TLA). The building blocks of this model include:(1) a sequence of states expressed by attributes of subjects, objects, and the system, (2) state predicates on subject andobject attributes, (3) pre-defined authorization actions performed by the security system and subjects, (4) obligation actions, and(5) condition predicates on system attributes. For a UCON model we define a set of temporal logic formulas that hold as usage control policies. We show the flexibility and expressive capability of this logic model by specifying the new features and core models of UCON.