2,006 research outputs found
Towards distributed hash tables (De)composition in ambient networks
No full textWhen different wireless networks come in close proximity there is often a need for them to logically combine, or compose. We focus on a known research problem particularly in Ambient Networks (ANs), where heterogeneous Distributed Hash Tables (DHTs) contained in these wireless networks need to merge or divide as a result of these dynamic (de)composition processes, respectively. We present two novel DHT (de)composition models for ANs, known as absorption and gatewaying, that are designed to handle (de)composition of DHTs in different AN network environments, with minimal disturbance to existing member nodes
XML Data Integrity Based on Concatenated Hash Function
Get PDFData integrity is the fundamental for data authentication. A major problem for XML data authentication is that signed XML data can be copied to another document but still keep signature valid. This is caused by XML data integrity protecting. Through investigation, the paper discovered that besides data content integrity, XML data integrity should also protect element location information, and context referential integrity under fine-grained security situation. The aim of this paper is to propose a model for XML data integrity considering XML data features. The paper presents an XML data integrity model named as CSR (content integrity, structure integrity, context referential integrity) based on a concatenated hash function. XML data content integrity is ensured using an iterative hash process, structure integrity is protected by hashing an absolute path string from root node, and context referential integrity is ensured by protecting context-related elements. Presented XML data integrity model can satisfy integrity requirements under situation of fine-grained security, and compatible with XML signature. Through evaluation, the integrity model presented has a higher efficiency on digest value-generation than the Merkle hash tree-based integrity model for XML data
Bridging distributed hash tables in wireless ad-hoc networks
Get PDFThe adaptation of structured P2P networks, i.e.
Distributed Hash Tables (DHTs), to wireless ad-hoc networks has
been investigated in recent years. Existing work assume all peers
would come to an agreement on establishing one uniform DHT
across the entire network. However, in reality, there isn’t a defacto
standard of DHT implementation, different DHTs co-exist.
We present a novel protocol, known as the DHT-gatewaying
model, which enables cross-DHT searching between multiple
DHTs of different implementations
Finding state-of-the-art non-cryptographic hashes with genetic programming
Get PDFProceding of: 9th International Conference, Reykjavik, Iceland, September 9-13, 2006.The design of non-cryptographic hash functions by means of evolutionary computation is a relatively new and unexplored problem. In this paper, we use the Genetic Programming paradigm to evolve collision free and fast hash functions. For achieving robustness against collision we use a fitness function based on a non-linearity concept, producing evolved hashes with a good degree of Avalanche Effect. The other main issue, efficiency, is assured by using only very fast operators (both in hardware and software) and by limiting the number of nodes. Using this approach, we have created a new hash function, which we call gp-hash, that is able to outperform a set of five human-generated, widely-used hash functions.This article has been financed by the Spanish founded research MCyT project
OP:LINK, Ref:TIN2005-08818-C04-02
Evaluation of hash functions for multipoint sampling in IP networks
No full textNetwork Measurements play an essential role in operating and developing todays Internet. A variety of measurement applications demand for multipoint network measurements, e.g. service providers need to validate their delay guarantees from Service Level Agreements and network engineers have incentives to track where packets are changed, reordered, lost or delayed. Multipoint measurements create an immense amount of measurement data which demands for high resource measurement infrastructure. Data selection techniques, like sampling and filtering, provide efficient solutions for reducing resource consumption while still maintaining sufficient information about the metrics of interest. But not all selection techniques are suitable for multipoint measurements; only deterministic filtering allows a synchronized selection of packets at multiple observation points. Nevertheless a filter bases its selection decision on the packet content and hence is suspect to bias, i.e. the selected subset is not representative for the whole population. Hash-based selection is a filtering method that tries to emulate random selection in order to obtain a representative sample for accurate estimations of traffic characteristics. The subject of the thesis is to assess which hash function and which packet content should be used for hash-based selection to obtain a seemingly random and unbiased selection of packets. This thesis empirically analyzes 25 hash functions and different packet content combinations on their suitability for hash-based selection. Experiments are based on a collection of 7 real traffic groups from different networks
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