| 1. |
- Anderson, Kristin, 1977-, et al.
(författare)
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Effects of User Adjacency in the Subset Difference Scheme for Broadcast Encryption
- 2005
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Ingår i: Radiovetenskap och Kommunikation, RVK05,2005.
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Konferensbidrag (refereegranskat)abstract
- We consider the broadcast encryption problem where one sender wishes to transmit messages securely to a selected set of receivers using a broadcast channel, as is the case in digital television for example. Specifically, we study the subset difference scheme for broadcast encryption and the number of broadcast transmissions required when using this scheme. The effects of adjacency in the user set are considered and we introduce the notion of transitions in the user set as a means to quantify the adjacency. We present upper and lower bounds for the number of transmissions based on the number of transitions between privileged and nonprivileged users in the user set. For cases where the privileged users are gathered in a few groups we derive the maximum number of transmissions.
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| 2. |
- Anderson, Kristin, 1977-, et al.
(författare)
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The Algebraic Structure of a Broadcast Encryption Scheme
- 2005
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Ingår i: Radiovetenskap och Kommunikation, RVK05,2005.
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Konferensbidrag (refereegranskat)abstract
- In this paper we consider the subset difference scheme for broadcast encryption and count the number of required broadcast transmissions when using this scheme. The subset difference scheme organizes receivers in a tree structure and we note that isomorphic trees yield the same number of required broadcast transmissions. Based on the isomorphism the trees can be partitioned into classes. We suggest to use the vast amount of tools available from the theory of groups to analyze the subset difference scheme and therefore we formulate the mappings between isomorphic trees using concepts from group theory. Finally we identify some research issues for further study of the performance of the subset difference scheme using group theory.
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| 3. |
- Anderson, Kristin, 1977-
(författare)
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Tree Structures in Broadcast Encryption
- 2005
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The need for broadcast encryption arises when a sender wishes to securely distribute messages to varying subsets of receivers, using a broadcast channel, for instance in a pay-TV scenario. This is done by selecting subsets of users and giving all users in the same subset a common decryption key. The subsets will in general be overlapping so that each user belongs to many subsets and has several different decryption keys. When the sender wants to send a message to some users, the message is encrypted using keys that those users have. In this thesis we describe some broadcast encryption schemes that have been proposed in the literature. We focus on stateless schemes which do not require receivers to update their decryption keys after the initial keys have been received; particularly we concentrate on the Subset Difference (SD) scheme.We consider the effects that the logical placement of the receivers in the tree structure used by the SD scheme has on the number of required transmissions for each message. Bounds for the number of required transmissions are derived based on the adjacency of receivers in the tree structure. The tree structure itself is also studied, also resulting in bounds on the number of required transmissions based on the placement of the users in the tree structure.By allowing a slight discrepancy between the set of receivers that the sender intends to send to and the set of receivers that actually can decrypt the message, we can reduce the cost in number of transmissions per message. We use the concept of distortion to quantify the discrepancy and develop three simple algorithms to illustrate how the cost and distortion are related.
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| 4. |
- Gehrmann, Christian, et al.
(författare)
-
Trust Evaluation for Embedded Systems Security research challenges identified from an incident network scenario
- 2011. - 10
-
Konferensbidrag (refereegranskat)abstract
- This paper is about trust establishment and trust evaluations techniques. A short background about trust, trusted computing and security in embedded systems is given. An analysis has been done of an incident network scenario with roaming users and a set of basic security needs has been identified. These needs have been used to derive security requirements for devices and systems, supporting the considered scenario. Using the requirements, a list of major security challenges for future research regarding trust establishment in dynamic networks have been collected and elaboration on some different approaches for future research has been done.This work was supported by the Knowledge foundation and RISE within the ARIES project.
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| 5. |
- Lindkvist, Tina, et al.
(författare)
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A class of traceability codes
- 2002
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Ingår i: IEEE Transactions on Information Theory. - 0018-9448 .- 1557-9654. ; 48:7, s. 2094-2096
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Tidskriftsartikel (refereegranskat)abstract
- Traceability codes are identifiable parent property (IPP) codes with the additional requirement that Hamming distance can be used to trace a parent of a word. Traceability codes can be used for constructing digital fingerprints in order to deter users from illegally copying digital data. We construct a class of traceability codes and determine the exact parameters of some of the codes in this class.
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| 6. |
- Lindkvist, Tina, 1971-, et al.
(författare)
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A Power-Efficient, Low-Complexity, Memoryless Coding Scheme for Buses with Dominating Inter-Wire Capacitances
- 2004
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Ingår i: IEEE International Workshop on System on Chip for Real-Time Applications,2004. - Los Alamitos, California, USA : IEEE Computer Society. ; , s. 257-
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Konferensbidrag (refereegranskat)abstract
- In this paper we present a simplified model of parallel, on-chip buses, motivated by the movement toward CMOS technologies where the ratio between inter-wire capacitance and wire-to-ground capacitance is very large. We also introduce a ternary bus state representation, suitable for the bus model. Using this representation we propose a coding scheme without memory which reduces energy dissipation in the bus model by approximately 20-30% compared to an uncoded system. At the same time the proposed coding scheme is easy to realize, in terms of standard cells needed, compared to several previously proposed solutions.
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| 7. |
- Lindkvist, Tina, 1971-, et al.
(författare)
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Deep Sub-Micron Bus Invert Coding
- 2004
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Ingår i: Proceedings of the 6th Nordic Signal Processing Symposium, 2004. NORSIG 2004.. - Helsinki : University of Technology. - 951227065X ; , s. 133-136
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Konferensbidrag (refereegranskat)abstract
- In this paper we present a simplified model for deep sub-micron, on-chip, parallel data buses. Using this model a coding technique similar to Bus Invert Coding is presented, but with a better performance in the proposed model. The coding technique can be realized using low-complexity encoding and decoding circuitry, and with a complexity that scales linearly with the bus width. Simulation results show that the energy dissipation decreases with approximately 20% for buses with up to 16 wires.
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| 8. |
- Lindkvist, Tina, 1971-, et al.
(författare)
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Descendant Set Models in Fingerprinting Systems
- 2004
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In a fingerprinting system, the tracing properties are not properties only of the code, they are also dependent of how descendant words can be created. In this correspondence a simple characterization of descendant set models is presented, and relations between different tracing properties in these descendant set models are derived.
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| 9. |
- Löfvenberg, Jacob, 1971-, et al.
(författare)
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A Model for Mobility-Based Communication in Ad Hoc Networks
- 2005
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Ingår i: The Third Swedish National Computer Networking Workshop,2005.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We introduce the concept of mobility-based communication in ad hoc networks, meaning that the packet transport is performed mainly by the nodes' movement. We outline a model for such networks, utilizing a stochastic model for the geographical location of the nodes. A test case is defined in which three strategies for packet forwarding are presented and evaluated.
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| 10. |
- Löfvenberg, Jacob, 1971-
(författare)
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Binary Fingerprinting Codes
- 2005
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Ingår i: Designs, Codes and Cryptography. - : Springer Science and Business Media LLC. - 0925-1022 .- 1573-7586. ; 36:1, s. 69-81
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Tidskriftsartikel (refereegranskat)abstract
- Three binary fingerprinting code classes with properties similar to codes with the identifiable parent property are proposed. In order to compare such codes a new combinatorial quality measure is introduced. In the case of two cooperating pirates the measure is derived for the proposed codes, upper and lower bounds are constructed and the results of computer searches for good codes in the sense of the quality measure are presented. Some properties of the quality measure are also derived.
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| 11. |
- Löfvenberg, Jacob, 1971-
(författare)
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Codes for digital fingerprinting
- 2001
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Illegal, copying of data is a problem in many areas. Despite various efforts in copy protection and copyright enforcement the problem still exists, and with the growing use of digital means of storing and distributing data the problem seems to be getting worse.Storing a unique, invisible marking in each distributed object is a possible way of dealing with the problem of illegal copying. That way, if an illegal copy is found somewhere, it is possible to find the original holder of the object. This type of scheme is called fingerprinting.The thesis deals with codes for fingerprinting of digital data in the context of several users colluding to create an untraceable, illegal copy. Some theoretical bounds on the performance of such codes are presented. A general method to statistically test whether certain users have taken part in the creation of a particular illegal copy is presented, and pirate strategies that prevent this kind of testing are derived. A simple testing method is presented that tests whether a certain, proposed group of users should be considered guilty of having created a specific illegal fingerprint. The set of possible pirate strategiesis derived and a compact representation is presented. It is shown that the fingerprinting problem is fundamentally a game theoretical problem. Finally, a combinatorial performance measure for binary fingerprinting codes is presented, and several code constructions are analyzed using this measure.
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| 12. |
- Löfvenberg, Jacob, 1971-
(författare)
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Coding circuits for reducing Hamming weight
- 2005
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Ingår i: Radiovetenskap och Kommunikation, RVK05,2005.
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Konferensbidrag (refereegranskat)abstract
- Using a newly introduced alternative to a conventional SRAM cell a binary zero can be written with a much lower power consumption than a binary one. Such a solution reduces power consumption, especially if there are few ones in the data, that is, if the data has a low Hamming weight. If the data is not inherently of low weight, this can be achieved by encoding the data. In the paper such coding is discussed and in small cases energy efficient encoding and decoding realizations are presented.
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| 13. |
- Löfvenberg, Jacob, 1971-, et al.
(författare)
-
Coding schemes for deep sub-micron data buses
- 2005
-
Ingår i: Radiovetenskap och Kommunikation, RVK05,2005.
-
Konferensbidrag (refereegranskat)abstract
- We present two coding techniques for reducing the power dissipation in deep sub-micron, parallel data buses. The techniques differ in their parameter values and are suitable in different scenarios. In both cases typical reduction in power dissipation is 20%.
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| 14. |
- Löfvenberg, Jacob, 1971-
(författare)
-
Coding schemes for highly sequential data in deep sub-micron buses
- 2005
-
Ingår i: Radiovetenskap och Kommunikation, RVK05,2005.
-
Konferensbidrag (refereegranskat)abstract
- We discuss coding for deep sub-micron buses with highly sequential data, the typical application being address buses, and we note that coding techniques specifically targetted at this application are considerably better than general techniques. Previously proposed coding schemes are described and a new, non-redundant coding technique with a very small realization and more than 50% reduction of power dissipation is presented.
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| 15. |
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| 16. |
- Löfvenberg, Jacob, 1971-, et al.
(författare)
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Minimal Redundancy, Low Power Bus Coding
- 2005
-
Ingår i: 23rd NORCHIP Conference,2005. - Oulu, Finland : University Oulu. ; , s. 277-
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Konferensbidrag (refereegranskat)abstract
- A new approach to low redundancy coding for reducing power dissipation in parallel on-chip, deep sub-micron buses is presented. It is shown that the new approach allows lower power dissipation than previous solutions in the given model, yielding reductions of 24% to 41% compared to uncoded transmission for the considered bus widths. Finally some important open problems are given.
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| 17. |
- Löfvenberg, Jacob, 1971-
(författare)
-
Non-Redundant Coding for Deep Sub-Micron Address Buses
- 2004
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Ingår i: IEEE International Workshop on System on Chip for Real-Time Applications,2004. - Los Alamitos, California, USA : IEEE Computer Societiy. ; , s. 275-
-
Konferensbidrag (refereegranskat)abstract
- A coding technique for deep sub-micron address buses with inter-wire capacitances dominating the wire-to-ground capacitances is presented. This code is similar to Gray codes, in the sense that it defines an ordering of the binary space, such that adjacent codewords dissipate little energy when sent consecutively. The ordering is shown to be close to optimal, as to the energy dissipation, when sending the whole sequence in order. A circuit diagram realizing the coder is presented, using only n-1 two-input gates, where n is the bus width. Simulations show an improvement in energy dissipation of more than 50% over an uncoded bus in several cases, depending on the data being coded.
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