Person:

Ahamad, Mustaque

Permanent Link

https://hdl.handle.net/1853/71046

Associated Organization(s)

Organizational Unit

School of Computer Science

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Publication Search Results

Now showing 1 - 10 of 11

A Patient-centric, Attribute-based, Source-verifiable Framework for Health Record Sharing

(Georgia Institute of Technology, 2009) Mohan, Apurva ; Bauer, David ; Blough, Douglas M. ; Ahamad, Mustaque ; Bamba, Bhuvan ; Krishnan, Ramkumar ; Liu, Ling ; Mashima, Daisuke ; Palanisamy, Balaji

The storage of health records in electronic format, and the wide-spread sharing of these records among different health care providers, have enormous potential benefits to the U.S. healthcare system. These benefits include both improving the quality of health care delivered to patients and reducing the costs of delivering that care. However, maintaining the security of electronic health record systems and the privacy of the information they contain is paramount to ensure that patients have confidence in the use of such systems. In this paper, we propose a framework for electronic health record sharing that is patient centric, i.e. it provides patients with substantial control over how their information is shared and with whom; provides for verifiability of original sources of health information and the integrity of the data; and permits fine-grained decisions about when data can be shared based on the use of attribute-based techniques for authorization and access control. We present the architecture of the framework, describe a prototype system we have built based on it, and demonstrate its use within a scenario involving emergency responders' access to health record information.
Privacy Preserving Grapevines: Capturing Social Network Interactions Using Delegatable Anonymous Credentials

(Georgia Institute of Technology, 2009) Balasubramaniyan, Vijay A. ; Lee, Younho ; Ahamad, Mustaque

A wide variety of services allow users to meet online and communicate with each other, building new social relationships and reinforcing older ones. Unfortunately, malicious entities can exploit such services for fraudulent activities such as spamming. It is critical that these services protect users from unwanted interactions, especially when new relationships are being established - the introduction problem. The problem of assessing that a social network connection is no longer beneficial is also important due to the dynamic nature of such networks. A large number of new connections are established through existing, weak social ties (for example, friend of a friend). On the other hand, the willingness of a user to continue interactions with an existing relationship is an indication of his or her endorsement of that relationship. The interaction history of a user provides valuable information about both new social network connections and the validity of established ones. However, capturing this interaction history is rife with privacy concerns. In this paper, we create a transferable token framework, based on delegatable anonymous credentials (DAC - Crypto 2009), that captures interaction history in a privacy preserving manner. By using the Groth Sahai proof system, we extend DACs to allow for single use tokens with the ability to identify token double spenders. We show that such tokens can, simultaneously, demonstrate the existence of a social network path and capture the continued validity of a social network connection. We present an implementation of this DAC based token framework and utilize it in a Voice over IP (VoIP) setting to enable legitimate user interactions in the presence of a spammer threat model. Our results indicate that we are able to achieve low false positive and false negative rates for realistic threat scenarios without disclosing a user’s social network connections.
ITR/SI: Guarding the next internet frontier: countering denial of information

(Georgia Institute of Technology, 2008-12-19) Ahamad, Mustaque ; Omiecinski, Edward ; Pu, Calton ; Mark, Leo ; Liu, Ling
Emerging Cyber Threats Report for 2009

(Georgia Institute of Technology, 2008-10-15) Ahamad, Mustaque ; Amster, Dave ; Barrett, Michael ; Cross, Tom ; Heron, George ; Jackson, Don ; King, Jeff ; Lee, Wenke ; Naraine, Ryan ; Ollmann, Gunter ; Ramsey, Jon ; Schmidt, Howard A. ; Traynor, Patrick

On October 15, 2008, the Georgia Tech Information Security Center (GTISC) hosted its annual summit on emerging security threats and countermeasures affecting the digital world. At the conclusion of the event, GTISC released this Emerging Cyber Threats Report—outlining the top five information security threats and challengesfacing both consumer and business users in 2009. This year’s summit participants include security experts from the public sector, private enterprise and academia, reinforcing GTISC’s collaborative approach to addressing information security technology and policy challenges. "As one of the leading academic research centers focused on information security, GTISC believes strongly that a proactive and collaborative approach to understanding emerging threats will help us develop more effective information security technologies and strategies," said Mustaque Ahamad, director of GTISC. "The annual GTISC Security Summit on Emerging Cyber Security Threats and our annual Emerging Cyber Threats Report seek to give us a better understanding of the cyber security challenges we will face in the years ahead." GTISC research and advance interviews with key information security experts from government, industry and academia uncovered five specific trends and some profound questions that will drive threats and countermeasures in 2009 and beyond, including: Malware, Botnets, Cyber warfare, Threats to VoIP and mobile devices, and The evolving cyber crime economy. In an effort to inform the broader community about current and future risks, this report will describe each emerging threat, existing or potential countermeasures, and how the threat may evolve in the coming year. In addition, our experts will offer their opinion on the role that Internet security education and regulation may play in further preventing the spread of cyber crime.
Using Byzantine Quorum Systems to Manage Confidential Data

(Georgia Institute of Technology, 2004-04-01) Subbiah, Arun ; Ahamad, Mustaque ; Blough, Douglas M.

This paper addresses the problem of using proactive cryptosystems for generic data storage and retrieval. Proactive cryptosystems provide high security and confidentiality guarantees for stored data, and are capable of withstanding attacks that may compromise all the servers in the system over time. However, proactive cryptosystems are unsuitable for generic data storage uses for two reasons. First, proactive cryptosystems are usually used to store keys, which are rarely updated. On the other hand, generic data could be actively written and read. The system must therefore be highly available for both write and read operations. Second, existing share renewal protocols (the critical element to achieve proactive security) are expensive in terms of computation and communication overheads, and are time consuming operations. Since generic data will be voluminous, the share renewal process will consume substantial system resources and cause a significant amount of system downtime. Two schemes are proposed that combine Byzantine quorum systems and proactive secret sharing techniques to provide high availability and security guarantees for stored data, while reducing the overhead incurred during the share renewal process. Several performance metrics that can be used to evaluate proactively-secure generic data storage schemes are identified. The proposed schemes are thus shown to render proactive systems suitable for confidential generic data storage.
Collective Endorsement and the Dissemination Problem in Malicious Environments

(Georgia Institute of Technology, 2004-03-08) Lakshmanan, Subramanian ; Manohar, Deepak J. ; Ahamad, Mustaque ; Venkateswaran, H.

We consider the problem of disseminating an update known to a set of servers to other servers in the system via a gossip protocol. Some of the servers can exhibit malicious behavior. We require that only the updates introduced by authorized clients are accepted by non-malicious servers. Spurious updates, in particular those generated by compromised nodes, are not accepted by non-malicious servers. We take the approach of collective endorsement where each server endorses an accepted update by computing a list of message authentication codes with symmetric keys allocated to it. We use a novel key allocation scheme that allocates a set of symmetric keys to each participating server to minimize the total number of keys. Our protocol is designed to minimize update diffusion time. In the absence of faulty nodes, its diffusion time is O(log n), which is the best possible time achieved when nodes only suffer from benign faults. If the actual number of Byzantine faults experienced during an update's dissemination is f, the diffusion time increases to O(log n + f). This is better than the latency of previously known protocols that take O(log n + b) time, where b is the assumed threshold that defines the maximum number of malicious servers that can be tolerated rather than f, the actual number of failures. The buffer requirements and message sizes are higher in our protocol than other known protocols and thus it trades off memory and bandwidth resources to improve latency.
Responsive Security for Stored Data

(Georgia Institute of Technology, 2002) Lakshmanan, Subramanian ; Ahamad, Mustaque ; Venkateswaran, H.

We present the design of a distributed store that offers various levels of security guarantees while tolerating a limited number of nodes that are compromised by an adversary. The store uses secret sharing schemes to offer security guarantees namely availability, confidentiality and integrity. However, a pure secret sharing scheme could suffer from performance problems and high access costs. We integrate secret sharing with replication for better performance and to keep access costs low. The tradeoffs involved between availability and access cost on one hand and confidentiality and integrity on the other are analyzed. Our system differs from traditional approaches such as state machine or quorum based replication that have been developed to tolerate Byzantine failures. Unlike such systems, we augment replication with secret sharing and demonstrate that such a hybrid scheme offers additional flexibility that is not possible with current schemes.
A Secure and Highly Available Distributed Store for Meeting Diverse Data Storage Needs

(Georgia Institute of Technology, 2000) Lakshmanan, Subramanian ; Ahamad, Mustaque ; Venkateswaran, H.

As computers become pervasive in environments like the home and community, data repositories that can maintain the long term state of applications will become increasingly important. Because of the greater reliance of people on such applications and the potentially sensitive nature of the data manipulated by them, the repository must be highly available and it should provide secure access to data. Furthermore, many different types of data, ranging from private data belonging to a single user to data shared across different users may be stored in the repository. We present the design of a distributed data repository, called a secure store, which can meet the data access needs of diverse applications. We develop protocols that replicate data at multiple servers to enhance availability and work even when a limited number of compromised servers exhibit arbitrary failure behavior. We also discuss how the nature of the data that is stored in the secure store impacts the availability and costs associated with data access.
Shared State Consistency for Time-sensitive Distributed Applications

(Georgia Institute of Technology, 2000) Krishnaswamy, Vijaykumar ; Ahamad, Mustaque ; Bakken, David E. ; Raynal, M. (Michel)

Distributed applications that share dynamically changing state are increasingly being deployed in wide-area environments. Such applications must access the state in a consistent manner, but the consistency requirements vary significantly from other systems. For example, shared memory models such as sequential consistency focus on the ordering of operations and the same level of consistency is provided to each process. In interactive distributed applications, the timeliness of updates becoming effective could be an extremely important consistency requirement and it could be different across different users. We propose a system that provides both non-timed and time sensitive read and write operations for manipulating dynamic shared state. For example, a timed read can be used by a process to read a recently written value whereas a timed write can make a new value available to all readers within a certain amount of time. We develop a consistency model that precisely defines the semantics of timed and non-timed read and write operations. A protocol that implements this model is also presented. We also describe an implementation and some performance measurements.
Securing Context-Aware Applications Using Environment Roles

(Georgia Institute of Technology, 2000) Covington, Michael J. ; Long, Wende ; Srinivasan, Srividhya ; Dey, Anind K. ; Ahamad, Mustaque ; Abowd, Gregory D.

In the future, a largely invisible and ubiquitous computing infrastructure will assist people with a variety of activities in the home and at work. The applications that will be deployed in such systems will create and manipulate private information and will provide access to a variety of other resources. Securing such applications is challenging for a number of reasons. Unlike traditional systems where access control has been explored, access decisions may depend on the context in which requests are made. We show how the well-developed notion of roles can be used to capture security-relevant context of the environment in which access requests are made. By introducing environment roles, we create a uniform access control framework that can be used to secure context-aware applications. We also present a security architecture that supports security policies that make use of environment roles to control access to resources.