To make cybersecurity concepts more accessible to non-technical students, we present our classroom-based study of CyberGuardian, an educational game designed to teach cryptographic primitives through simplified, real-world scenarios. Players assume the role of a cybersecurity advisor, providing guidance to simulated clients and analyzing authentic messages to assure confidentiality, data integrity, and authentication through three cryptographic primitives: symmetric encryption, asymmetric encryption, and digital signature. CyberGuardian is freely available, easy to deploy at scale, and implemented as a single-player offline game compatible with macOS and Windows. Our learning objectives are to enable students to: (1) Identify how an adversary can interfere with communications; (2) Explain how cryptographic primitives can mitigate dangers; and (3) Apply cryptographic primitives to reduce vulnerabilities.

MeetingMayhem is a web-based educational game focused on adversarial thinking in the context of network security. In particular, this game gently and non-technically introduces students without prior cybersecurity knowledge to the Dolev-Yao network intruder model. In MeetingMayhem, three students take on the roles of two agents and an adversary. Two agents need to agree on a time and location to exchange an essential asset. The agents communicate through a network controlled by the adversary without knowing the adversary's identity. The adversary can insert, block, or modify messages. Students can play different roles, try different strategies, interact with different players, and send different messages. MeetingMayhem is available as a Docker Image, with open-source code. MeetingMayhem provides an engaging and innovative way for novice students to learn about adversarial thinking and cryptography within 2 hours.

CyberGuardian is an interactive educational game that introduces students to foundational concepts in cybersecurity through authentic scenarios. Specifically, the game teaches students about cryptographic primitives and adversarial thinking. Targeted at students without computer science backgrounds, the game immerses players in practical cybersecurity challenges using simplified technical concepts. Players assume the role of a cybersecurity advisor, providing guidance to simulated clients and analyzing authentic messages to assure confidentiality, data integrity, and authentication through three cryptographic primitives: symmetric encryption, asymmetric encryption, and digital signature. Implemented as a single-player offline experience on Mac and Windows, CyberGuardian is scalable and broadly available.

We report on our experiences fielding MeetingMayhem, an interactive game that we developed, which introduces students to fundamental concepts in network security, cybersecurity, and adversarial thinking. The game is intended for students who do not necessarily have any prior background in computer science. Assuming the role of agents, two players exchange messages over a network to try to agree on a meeting time and location, while an adversary interferes with their plan. Following the Dolev-Yao model, the adversary has full control of the network: they can see all messages and modify, block, or forward them. We designed the game as a web application, where groups of three students play the game, taking turns being the adversary. The adversary is a legitimate communicant on the network, and the agents do not know who is the other agent and who is the adversary. Through gameplay, we expect students to be able to (1) identify the dangers of communicating through a computer network, (2) describe the capabilities of a Dolev-Yao adversary, and (3) apply three cryptographic primitives: symmetric encryption, asymmetric encryption, and digital signatures. We conducted surveys, focus groups, and interviews to evaluate the effectiveness of the game in achieving the learning objectives. The game helped students achieve the first two learning objectives, as well as using symmetric encryption. We found that students enjoyed playing Meeting Mayhem. We are revising MeetingMayhem to improve its user interface and to better support students to learn about asymmetric encryption and digital signatures.

We present a psychometric evaluation of the Cybersecurity Curriculum Assessment (CCA), completed by 193 students from seven colleges and universities. The CCA builds on our prior work developing and validating a Cybersecurity Concept Inventory (CCI), which measures students' conceptual understanding of cybersecurity after a first course in the area. The CCA deepens the conceptual complexity and technical depth expectations, assessing conceptual knowledge of students who had completed multiple courses in cybersecurity. We review our development of the CCA and present our evaluation of the instrument using Classical Test Theory and Item-Response Theory. The CCA is a difficult assessment, providing reliable measurements of student knowledge and deeper information about high-performing students.

We present a psychometric evaluation of a revised version of theCybersecurity Concept Inventory (CCI), completed by 354 students from 29 colleges and universities. The CCI is a conceptual test of understanding created to enable research on instruction quality in cybersecurity education. This work extends previous expert review and small-scale pilot testing of the CCI. Results show that the CCI aligns with a curriculum many instructors expect from an introductory cybersecurity course, and that it is a valid and reliable tool for assessing what conceptual cybersecurity knowledge students learned.

We analyze expert review and student performance data to evaluate the validity of the Cybersecurity Concept Inventory (CCI) for assessing student knowledge of core cybersecurity concepts after a first course on the topic. A panel of 12 experts in cybersecurity reviewed the CCI, and 142 students from six different institutions took the CCI as a pilot test. The panel reviewed each item of the CCI and the overwhelming majority rated every item as measuring appropriate cybersecurity knowledge. We administered the CCI to students taking a first cybersecurity course either online or proctored by the course instructor. We applied classical test theory to evaluate the quality of the CCI. This evaluation showed that the CCI is sufficiently reliable for measuring student knowledge of cybersecurity and that the CCI may be too difficult as a whole. We describe the results of the expert review and the pilot test and provide recommendations for the continued improvement of the CCI.

Despite the documented need to train and educate more cybersecurity professionals, we have little rigorous evidence to inform educators on effective ways to engage, educate, or retain cybersecurity students. To begin addressing this gap in our knowledge, we are conducting a series of think-aloud interviews with cybersecurity students to study how students reason about core cybersecurity concepts. We have recruited these students from three diverse institutions: University of Maryland, Baltimore County, Prince George's Community College, and Bowie State University. During these interviews, students grapple with security scenarios designed to probe student understanding of cybersecurity, especially adversarial thinking. We are analyzing student statements using a structured qualitative method, novice-led paired thematic analysis, to document student misconceptions and problematic reasonings. We intend to use these findings to develop Cybersecurity Assessment Tools that can help us assess the effectiveness of pedagogies. These findings can also inform the development of curricula, learning exercises, and other educational materials and policies.

We present and experimentally evaluate Spread Identity (SI) – a new dynamic network address remapping mechanism that provides anonymity and DDoS defense capabilities for Internet communications. For each session between a source and destination host, the trusted source gateway dynamically and randomly assigns an IP address for the source host from the pool of all routable IP addresses allocated to the source organization. Similarly, in response to a name resolution query from the source gateway, the trusted authoritative DNS server for the destination organization dynamically assigns an IP address for the destination host from the pool of all routable IP addresses allocated to the destination organization. These assignments depend upon the state of the server (including load, residual capacity, time of day) and policy. Different hosts can share the same IP address when communicating with distinct peers. Each gateway creates a NAT entry, valid for the communication session, based on the dynamic assignment by its organization. An eavesdropper listening to packets flowing through the Internet between the source and destination gateways learns only the source and destination domains; the eavesdropper cannot see the actual complete IP addresses of the source and destination hosts. In addition, SI enhances DDoS defense capabilities by enabling packet filtering based on destination addresses. With multiple IP addresses for the same destination, filtering based on destination addresses can block attackers without necessarily blocking legitimate users. Deploying SI requires changes to organizational gateways and, possibly, to the edge-routers that interface with organizational gateways; but network mechanisms farther upstream, including the core routers in the Internet, remain unchanged. Likewise, the installed base of operating systems running individual hosts in the internal network, together with the end-user application suites they support, remain untouched. SI mechanisms are backward compatible, incrementally deployable, and robustly scalable. A naïve implementation of SI can increase the DNS traffic; however, when SI is implemented at both the source and the destination ends, it is possible for SI to reduce DNS traffic. Ns-2 simulations and experiments on the DeterLab test bed corroborate the main hypotheses and demonstrate advantages of the SI paradigm. Ns-2 simulations demonstrate that file transfer success rates for our SI DDoS protection mechanism are similar to those of filter- and capability-based approaches, with lower file transfer times than for filter-based approaches. DeterLab trials demonstrate that SI consumes similar resources (connection establishment time, network address translation table size, packet forwarding rate and memory) to those of a typical single NAT system, though with higher name resolution times.

We present Change-Link, a customizable data exploration tool which empowers the user to see visual representations of directories that have changed over time within a computer operating system that supports the Microsoft Volume Shadow Copy Service (VSS). Change-Link displays change information in a split-screen interface comprising an overview of directory change for the entire dataset and a detail view of change for individual directories. Input to Change-Link is an evidence hard drive containing an active file system and previous versions of the directory structure that were archived by the VSS. This approach to browsing change within a directory structure helps a digital forensic examiner understand how a particular computer was used to support criminal activity. Because data that have changed are often the most important, identifying directories that have changed over time directs attention towards data of higher importance. By examining the most important data, digital forensic examiners are better able to keep pace with the data explosion that is making current digital forensic examinations unmanageable. Our contributions include the development of a segmented box and whisker glyph for representing change over time for individual directories, an approach for aggregating VSS data for digital forensic examinations, and a data visualization tool for exploring digital forensic data.

Maintaining the confidentiality of data sent to clouds is a vital issue that must be satisfactorily resolved as a pre-condition in order for the cloud computing paradigm to survive and thrive. In this paper we explore a completely new paradigm to approximately achieve the functionality implied by "Oblivious Data Processing(ODP)". Our strategy is to partition the data as well as the underlying Residue Number System (RNS) in the Residue Domain (RD) and then distribute and process the partitions independently. We have also outlined some new fundamental limitations to ODP in general and identified application scenarios where ODP can be achieved as well as those wherein ODP appears to be doomed to fail in the long run.

In the above titled paper (ibid., vol. 4, no. 4, pp. 611-627, Dec. 09), due to a production error, the affiliations of two of the authors were listed incorrectly. The correct affiliations are presented here. Also, the name of the last author in the affiliations footnote was printed incorrectly. The correct name is P. Y. A. Ryan.

In the above titled paper (ibid., vol. 4, no. 4, pp. 628-637, Dec. 09), the fourth sentence of the Abstract contains an error. The correct sentence is presented here.

Scantegrity II is an enhancement for existing paper ballot systems. It allows voters to verify election integrity - from their selections on the ballot all the way to the final tally - by noting codes and checking for them online. Voters mark Scantegrity II ballots just as with conventional optical scan, but using a special ballot marking pen. Marking a selection with this pen makes legible an otherwise invisible preprinted confirmation code. Confirmation codes are independent and random for each potential selection on each ballot. To verify that their individual votes are recorded correctly, voters can look up their ballot serial numbers online and verify that their confirmation codes are posted correctly. The confirmation codes do not allow voters to prove how they voted. However, the confirmation codes constitute convincing evidence of error or malfeasance in the event that incorrect codes are posted online. Correctness of the final tally with respect to the published codes is proven by election officials in a manner that can be verified by any interested party. Thus, compromise of either ballot chain of custody or the software systems cannot undetectably affect election integrity. Scantegrity II has been implemented and tested in small elections in which ballots were scanned either at the polling place or centrally. Preparations for its use in a public sector election have commenced.

We reduce the required trusted computing base for direct recording electronic (DRE) voting machines with a design based on trusted platform modules (TPMs). Our approach ensures election data integrity by binding the voter's choices with the presented ballot using a platform vote ballot (PVB) signature key managed by the TPM. The TPM can use the PVB key only when static measurements of the software reflect an uncompromised state and when a precinct judge enters a special password revealed on election day. Using the PVB with the TPM can expose authorized software, ballot modifications, vote tampering, and creation of fake election records early in the election process. Our protocol places trust in tamper resistant hardware, not in mutable system software. Although we are not the first to suggest using TPMs in voting, we are the first to provide a detailed engineering protocol that binds the voter choices with the presented ballot and uses the TPM to enforce election policy. We present the protocol, architecture, assumptions, and security arguments in enough detail to support further analysis or implementation.

We present, implement, and analyze a new scalable centralized algorithm, called OFT, for establishing shared cryptographic keys in large, dynamically changing groups. Our algorithm is based on a novel application of one-way function trees. In comparison with the top-down logical key hierarchy (LKH) method of Wallner et al., our bottom-up algorithm approximately halves the number of bits that need to be broadcast to members in order to rekey after a member is added or evicted. The number of keys stored by group members, the number of keys broadcast to the group when new members are added or evicted, and the computational efforts of group members, are logarithmic in the number of group members. Among the hierarchical methods, OFT is the first to achieve an approximate halving in broadcast length, an idea on which subsequent algorithms have built. Our algorithm provides complete forward and backward security: Newly admitted group members cannot read previous messages, and evicted members cannot read future messages, even with collusion by arbitrarily many evicted members. In addition, and unlike LKH, our algorithm has the option of being member contributory in that members can be allowed to contribute entropy to the group key. Running on a Pentium II, our prototype has handled groups with up to 10 million members. This algorithm offers a new scalable method for establishing group session keys for secure large-group applications such as broadcast encryption, electronic conferences, multicast sessions, and military command and control.

Article How to break Gifford's cipher (extended abstract) Share on Authors: Thomas R. Cain Computer Science Department, University of Maryland Baltimore County, Baltimore, Maryland Computer Science Department, University of Maryland Baltimore County, Baltimore, MarylandView Profile , Alan T. Sherman Computer Science Department, University of Maryland Baltimore County, Baltimore, Maryland Computer Science Department, University of Maryland Baltimore County, Baltimore, MarylandView Profile Authors Info & Claims CCS '94: Proceedings of the 2nd ACM Conference on Computer and communications securityNovember 1994 Pages 198–209https://doi.org/10.1145/191177.191227Online:02 November 1994Publication History 3citation540DownloadsMetricsTotal Citations3Total Downloads540Last 12 Months2Last 6 weeks0 Get Citation AlertsNew Citation Alert added!This alert has been successfully added and will be sent to:You will be notified whenever a record that you have chosen has been cited.To manage your alert preferences, click on the button below.Manage my AlertsNew Citation Alert!Please log in to your account Save to BinderSave to BinderCreate a New BinderNameCancelCreateExport CitationPublisher SiteGet Access

Abstract The Geometric Steiner Minimum Tree problem (GSMT) is to connect at minimum cost n given points (called terminals ) in d ‐dimensional Euclidean space. We generalize a GSMT approximation partitioning algorithm by Komlós and Shing (KS) and analyze its performance under more relaxed conditions. These generalizations have practical applications for multilayer VLSI routing. Whereas KS assumed d = 2, our algorithm works for any dimension d ⩾ 2. Moreover, whereas their analysis assumed the rectilinear norm and a uniform distribution of input points, our analysis holds for any norm on R d and whenever the terminals are any independent identically distributed random variables taking on values in any bounded subset of R d . Both algorithms depend on a parameter t through which the user can trade off time for solution quality. We evaluate our algorithm in terms of its performance ratio–the ratio of the cost of the Steiner tree computed by the algorithm divided by the cost of a Steiner minimum tree. Applying a probability theorem on subadditive Euclidean functionals by Steele, we prove the following: Under the aforementioned distribution of inputs, the limit as n → ∞ of the supremum of the performance ratio of our algorithm is 1 + O t −1/ d ( d ‐1), almost surely. This result generalizes the corresponding 1 + O ( t −1/2 ) bound proven by KS. Along the way, we prove a useful combinatorial lemma about d ‐dimensional rectangle slicings. We prove that the worst‐case time and space complexity of our algorithm is θ( n lg ( n/t ) + T MST ( v, v ) + nT SMT ( t )/ t ) and θ( S MST ( v, v ) + S SMT ( t )), respectively, where v ⩽ n + 2 d +1 ( n/t ) σ( t ) is the number of vertices in the resulting Steiner tree. Here, T SMT ( t ) and S SMT ( t ) are the time and space required to solve exactly any GSMT problem of size less than t ; T MST ( n, m ) and S MST ( n, m ) are the time and space required to find a minimum spanning tree of a graph with n nodes and m edges; and σ( t ) is the maximum number of Steiner points for any Steiner minimum tree with t terminals. For example, for R 2 and the rectilinear norm, the time is O ( n lg( n/t ) + n lg* n + nT SMT ( t )/ t ) and the space is O ( n lg *n + S SMT ( t )). © 1994 by John Wiley & Sons, Inc.

Abstract We experimentally evaluate sequential and distributed implementations of an approximation partitioning algorithm by Kalpakis and Sherman for the Geometric Steiner Minimum Tree Problem (GSMT) in R d for d = 2,3. Our implementations incorporate an improved method for combining the subproblems, and single‐and double‐edge reduction techniques to eliminate unnecessary Steiner points created by the partitioning process. Results show that these refinements are crucial in practice to produce high‐quality results. Moreover, with these refinements, the partitioning algorithm is an effective practical heuristic, which in less time finds solutions roughly comparable with those computed by Smith's Algorithm. The partitioning algorithm depends on a parameter t through which the user can trade off time for solution quality. To solve each of the subproblems of size at most t , we apply Smith's Algorithm, the only other Steiner tree algorithm known for R 3 under the Euclidean norm. Using uniformly generated point sets in the d ‐cube [0, 100] d , we compare the running time and solution quality for the partitioning algorithm for various values of t against that of Smith's Algorithm applied to the entire input. We also estimate the constant factor in the 1 + O(t −1/d(d‐1) ) asymptotic performance bound proven by Kalpakis and Sherman and find that it is less than one. With d = 2 on input sets of 25 points, our sequential implementation with t = 7 typically found within 6 seconds a Steiner tree within 1% of the cost (342) of that computed by Smith's Algorithm in 20 seconds. At t = 13 and using approximately 15 seconds, our sequential implementation typically found Steiner trees within 0.1% of this cost. Similarly, with d = 3 on input sets of 60 points, our distributed implementation with t = 10 typically found within 22 seconds a Steiner tree within 1% of the cost (1059) of that computed by Smith's Algorithm in 200 seconds. At t = 31 and using approximately 108 seconds, our distributed implementation usually found slightly better Steiner trees than did Smith's Algorithm. © 1994 by John Wiley & Sons, Inc.

Given any irreversible program with running time T and space complexity S, and given any $\varepsilon > 0$, Bennett shows how to construct an equivalent reversible program with running time $O(T^{1+\varepsilon })$ and space complexity $O(S \ln T)$. Although these loose upper bounds are formally correct, they are misleading due to a hidden constant factor in the space bound. It is shown that this constant factor is approximately $\varepsilon 2^{1 / \varepsilon}$, which diverges exponentially as $\varepsilon$ approaches 0. Bennett’s analysis is simplified using recurrence equations and it is proven that the reversible program actually runs in time $\Theta ({{T^{1 + \varepsilon}} / {S^{\varepsilon}}})$ and space $\Theta (S(1+\ln ({T / S})))$. Bennett claims that for any $\varepsilon > 0$, the reversible program can be made to run in time $O(T)$ and space $O(ST^{\varepsilon })$. This claim is corrected and tightened as follows: whenever $T \geqq 2S$ and for any $\varepsilon \geqq {1 / {(0.58 \lg ({T / S}))}}$, the reversible program can be made to run in time $\Theta (T)$ and space $\Omega (S(T/S)^{\varepsilon/2})\cap O(S(T/S)^\varepsilon )$. For $S\leqq T < 2S$, Bennett’s 1973 simulation yields an equivalent reversible program that runs in time $\Theta (T)$ and space $\Theta (S)$.