| 1. |
- Arndt, D. S., et al.
(författare)
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STATE OF THE CLIMATE IN 2017
- 2018
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Ingår i: Bulletin of The American Meteorological Society - (BAMS). - : American Meteorological Society. - 0003-0007 .- 1520-0477. ; 99:8, s. S1-S310
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Forskningsöversikt (refereegranskat)
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| 2. |
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- 2019
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Tidskriftsartikel (refereegranskat)
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| 3. |
- Afanassiev, Valentin, et al.
(författare)
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Fast authentication codes based on random polynomial residue classes
- 1997
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Ingår i: Proceedings 1997 IEEE International Symposium on Information Theory. - 2157-8095. - 0780339568 - 9780780339569 ; , s. 175-175
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Konferensbidrag (refereegranskat)abstract
- The verification of the authenticity of a text document or a datafile is one of the main applications of cryptographic techniques. A common used technique for this purpose is the application of a message authentication code (MAC). Usually the MAC computation has to be done in software. Based on the relationship between error-correcting codes and so-called families of almost universal hash functions, and the error-correcting codes using polynomial residue classes we describe an efficient procedure for a MAC computation which is much faster than the standard MAC constructions using MD5 or SHA and uses much less key bits than the fast MACs based on bucket hashing.
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| 4. |
- Afanassiev, Valentine, et al.
(författare)
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Fast message authentication using efficient polynomial evaluation
- 1997
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Ingår i: Fast Software Encryption : 4th International Workshop, FSE 1997, Proceedings - 4th International Workshop, FSE 1997, Proceedings. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 1611-3349 .- 0302-9743. - 3540632476 - 9783540632474 ; 1267, s. 190-204
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Konferensbidrag (refereegranskat)abstract
- Message authentication codes (MACs) using polynomial evaluation have the advantage of requiring a very short key even for very large messages. We describe a low complexity software polynomial evaluation procedure, that for large message sizes gives a MAC that has about the same low software complexity as for bucket hashing but requires only small keys and has better security characteristics.
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| 5. |
- Alfredsson, Lars-Inge, 1964-
(författare)
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VLSI Architectures and Arithmetic Operations with Application to the Fermat Number Transform
- 1996
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The properties of arithmetic operations in Fermat integer quotient rings 2m+1, where m = 2t, are investigated. The arithmetic operations considered are mainly those involved in the computation of the Fermat number transform. We consider some ways of representing the binary coded integers in such rings and investigate VLSI architectures for arithmetic operations, with respect to the different element representations. The VLSI architectures are mutually compared with respect to area (A) and time (T) complexity and area-time performance (AT2). The VLSI model chosen is a linears witch-level RC model.In the polar representation, the nonzero elements of a field are represented by the powers of a primitive element of the field. In the thesis we particularly investigate the properties of arithmetic operations and their corresponding VLSI architectureswith respect to the polar representation of the elements of Fermat prime fields. Somenew results regarding the applicability of the Fermat number transform when usingthe polar representation are also presented.
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| 6. |
- 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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| 7. |
- Aslam, Mudassar, 1979-
(författare)
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Secure Service Provisioning in a Public Cloud
- 2012
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The evolution of cloud technologies which allows the provisioning of IT resources over the Internet promises many benefits for the individuals and enterprises alike. However, this new resource provisioning model comes with the security challenges which did not exist in the traditional resource procurement mechanisms. We focus on the possible security concerns of a cloud user (e.g. an organization, government department, etc.) to lease cloud services such as resources in the form of Virtual Machines (VM) from a public Infrastructure-as-a-Service (IaaS) provider. There are many security critical areas in the cloud systems, such as data confidentiality, resource integrity, service compliance, security audits etc. In this thesis, we focus on the security aspects which result in the trust deficit among the cloud stakeholders and hence hinder a security sensitive user to benefit from the opportunities offered by the cloud computing. Based upon our findings from the security requirements analysis,we propose solutions that enable user trust in the public IaaS clouds. Our solutions mainly deal with the secure life cycle management of the user VM which include mechanisms for VM launch and migration. The VM launch and migration solutions ensure that the user VM is always protected in the cloud by only allowing it to run on the user trusted platforms. This is done by using trusted computing techniques that allow the users to remotely attest and hence rate the cloud platforms trusted or untrusted. We also provide a prototype implementation to prove the implementation feasibility of the proposed trust enabling principles used in the VM launch and migration solutions.
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| 8. |
- Bergström, Daniel, et al.
(författare)
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Facilitating online trust with Blockchains
- 2019
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Ingår i: Ericsson Review (English Edition). - 0014-0171. ; 100:2, s. 8-17
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 9. |
- Bierbrauer, J., et al.
(författare)
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On the construction of universal families of hash functions via geometric codes and concatenation
- 1993
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Ingår i: Advances in Cryptology / Lecture Notes in Computer Science. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 1611-3349 .- 0302-9743. - 9783540577669 ; 773, s. 331-342
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Konferensbidrag (refereegranskat)abstract
- In this paper we use coding theory to give simple explanations of some recent results on universal hashing. We first apply our approach to give a precise and elegant analysis of the Wegman-Carter construction for authentication codes. Using Reed-Solomon codes and the well known concept of concatenated codes we can then give some new constructions, which require much less key size than previously known constructions. The relation to coding theory allows the use of codes from algebraic curves for the construction of hash functions. Particularly, we show how codes derived from Artin-Schreier curves, Hermitian curves and Suzuki curves yield good classes of universal hash functions.
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| 10. |
- Chepyshov, V., et al.
(författare)
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A simple algorithm for fast correlation attacks on stream ciphers
- 2000
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Ingår i: Fast Software Encryption / Lecture Notes in Computer Science. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 1611-3349 .- 0302-9743. - 9783540417286 ; 1978, s. 181-195
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Konferensbidrag (refereegranskat)abstract
- A new simple algorithm for fast correlation attacks on stream ciphers is presented. The advantages of the new approach are at least two. Firstly, the new algorithm significantly reduces the memory requirements compared with some recent proposals [2],[3]. This allows more powerful attacks than previously. Secondly, the simplicity of the algorithm allows us to derive theoretical results. We determine the relation between the number of observed symbols, the correlation probability, and the allowed computational complexity, required for a successful attack. Hence, we can get theoretical estimates on the required computational complexity in cases when simulation is not possible.
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