Search

This paper examines housing investment pressures and the local planning response in St Ives, Cornwall, where a Neighbourhood Development Plan introduced a principal residence restriction affecting all new-build homes in the locality in 2016. Ostensibly, the objective of this policy is to reserve new-build housing for local residents, thereby delivering improved housing market access for those needing to live and work in the area, who are seen to have greater claim on local resources. However, our study of the anticipated impacts of ‘Policy H2‘, drawing on semi-structured interviews with key policy informants and resident representatives, highlights concerns amongst long-term residents and working households as to the economic impacts of the policy relative to its impacts on housing access. Greater support for the policy was found to exist among in-migrant and retired households, who view the policy as a means of slowing development, preserving local character, and defending property values. Evidence from prior experiments with residence restrictions in the Lake District and elsewhere suggest that an overall reduction in house building (triggered by a shrinking of the market of eligible homebuyers) and a shift in demand by investors from new homes to the second-hand market can elevate house-prices and reduce overall housing affordability. Local needs planning policies may be politically expedient, with local politicians responding to a call to action, but they also carry the risk of unintended consequences.

Delay in publication of energy statistics prevents a timely assessment of progress towards meeting targets for energy saving and emission reduction in China. This makes it difficult to meet the requirements to rapidly monitor and evaluate energy consumption for each province. In this study, an alternative approach is provided to estimate the energy consumption by using satellite remote sensing data. We develop spatio-temporal geographically weighted regression models to simulate energy consumption of provinces in China based on the Defense Meteorological Satellite Program's Operational Linescan System (DMSP/OLS) global stable night-time light data. The models simulate China’s energy consumption accurately with the goodness of fit higher than 99%. Generally, the national average annual energy consumption is 2.8 billion tonnes of coal equivalent in China between 2000 and 2013, which is close to the actual value with errors smaller than 0.1%. From both temporal and spatial dimensions, the relative errors are smaller than 5.5% at the provincial level. Therefore, the use of satellite night-time light data provides a useful reference in monitoring and assessing provincial energy consumption in China.

International audience; In this work we present several new generic second-preimage attacks on hash functions. Our first attack is based on the herding attack, and applies to various Merkle-Damgård-based iterative hash functions. Compared to the previously known long-message second-preimage attacks, our attack offers more flexibility in choosing the second message in exchange for a small computational overhead. More concretely, in our attacks, the adversary may replace only a small number of blocks to obtain the second-preimage. As a result, the new attack is applicable to hash function constructions which were thought to be immune to the previously known second-preimage attacks. Such designs are the dithered hash proposal of Rivest, Shoup's UOWHF, and the ROX construction. We also suggest a few time-memory-data tradeoff variants for this type of attacks, allowing for a faster online phase, and even allow attacking significantly shorter messages than before. We follow and analyze the properties of the dithering sequence used in Rivest's hash function proposal, and develop a time-memory tradeoff which allows us to apply our second-preimage attack to a wider range of dithering sequences, including sequences which are much stronger than those in Rivest's proposals. Parts of our results rely on the kite generator, a new time-memory tradeoff tool. In addition to analysis of the Merkle-Damgård-like constructions, we analyze the security of the basic tree hash construction. We exhibit several second-preimage attacks on this construction, whose most notable variant is the time-memory-data tradeoff attack. Finally, we show how both the existing second-preimage attacks and our new attacks can be applied even more efficiently when multiple shorter rather than a single long target messages are given.

Most modern electronic devices can produce a random number. However, it is difficult to see how a group of mutually distrusting entities can have confidence in any such hardware-produced stream of random numbers, since the producer could control the output to their gain. In this work, we use public and immutable cryptocurrency smart contracts, along with a set of potentially malicious randomness providers, to produce a trustworthy stream of timestamped public random numbers. Our contract eliminates the ability of a producer to predict or control the generated random numbers, including the stored history of random numbers. We consider and mitigate the threat of collusion between the randomness providers and miners in a second, more complex contract.

PurposeThe purpose of this paper is to examine the relationship between health and safety (H&S) and organisational culture in project business, in particular to explore the validity of current cognitive emphases of linear organisational maturity towards a “safety culture”, and normative models and prescriptions.Design/methodology/approachAn interpretative methodology is employed, informed by ethnography (Douglas' cultural theory) and clinical consultative (Schein's model) approaches, using case‐based analysis comprising seven project business organisations.FindingsThe cases were characterized by diverse organisational cultures and diverse H&S practices informed by habits and intuitive behaviour, as well as cognitive strategies and decisions for implementation. H&S was not the top priority for these cases. Good performance related to alignment with the prevailing culture rather than pursuit of a “safety culture”.Research limitations/implicationsThe term “safety culture” is misdirected; greater attention on what is, rather than normative models and prescription, is necessary. Generalisation is limited by the case‐based approach.Practical implicationsPractitioners need to pay more attention to organisational culture and alignment of H&S practices, to the unintended consequences of prescriptions, and robust systems.Social implicationsThe way activities are conducted requires awareness of the prevailing culture in order to align the structure and processes to the culture for effective operations. These implications are general, and within project business and management, Failure to do so carries increased risk of failing to satisfy business and broader stakeholder interests.Originality/valueAnomalies in H&S research and practice are challenged, especially “safety culture” and normative approaches. The contribution is the combination employment of the Schein and Douglas models to understand organisational culture and H&S cultural alignment.

We analyse the security of iterated hash functions that compute an input dependent checksum which is processed as part of the hash computation. We show that a large class of such schemes, including those using non-linear or even one-way checksum functions, is not secure against the second preimage attack of Kelsey and Schneier, the herding attack of Kelsey and Kohno and the multicollision attack of Joux. Our attacks also apply to a large class of cascaded hash functions. Our second preimage attacks on the cascaded hash functions improve the results of Joux presented at Crypto’04. We also apply our attacks to the MD2 and GOST hash functions. Our second preimage attacks on the MD2 and GOST hash functions improve the previous best known short-cut second preimage attacks on these hash functions by factors of at least 226 and 254, respectively. Our herding and multicollision attacks on the hash functions based on generic checksum functions (e.g., one-way) are a special case of the attacks on the cascaded iterated hash functions previously analysed by Dunkelman and Preneel and are not better than their attacks. On hash functions with easily invertible checksums, our multicollision and herding attacks (if the hash value is short as in MD2) are more efficient than those of Dunkelman and Preneel.

The real tests for technology transfer are whether such transfers have contributed significantly to the vibrant development of the recipient industry. Technology transfer (TT) process that is knowledge driven demands a recipient industry with adequate capacity for absorbing new knowledge. International joint ventures and subcontracts employed in building material and construction can be serious vehicles of TT provided they contribute to providing higher quality inputs into the wider industry. These issues are examined through a survey of construction subcontracts during the period 1985–2002. The respondents indicated that moderately favourable conditions for TT existed in the completed projects. Nonetheless, the paper argues that negligible real productivity changes in construction in Sri Lanka in the recent decade point to stagnation in growth in local absorptive capacity. China in contrast has placed a balanced emphasis on upgrading building materials and equipment, design and construction, and built up...

Construction project planning is receiving growing attention as the limitations of formal deterministic planning are becoming more widely recognised. In particular, the last planner and critical chain approaches are diffusing rapidly. However, little of this debate has been informed by empirical examination of what construction project planners actually do. The research reported here draws on three different research projects. One on the overall context of construction project planning, and two focused on requirements capture for the virtual construction site system. For the later project, 18 construction planners were interviewed on their daily practice. The results show that construction planning for principal contractors is more about negotiation with other interested parties and rapid decision-making based on heuristics than detailed analysis.

Building on the work of Kocher (1996), Jaffe and Yun (1998), we discuss the notion of side-channel cryptanalysisc cryptanalysis using implementation data. We discuss the notion of side-channel attacks and the vulnerabilities they introduce, demonstrate side-channel attacks against three product ciphers - timing attack against IDEA, processor-flag attack against RC5, and Hamming weight attack against DES - and then generalize our research to other cryptosystems.

In many real-world applications, sensitive information must be kept it log files on an untrusted machine. In the event that an attacker captures this machine, we would like to guarantee that he will gain little or no information from the log files and to limit his ability to corrupt the log files. We describe a computationally cheap method for making all log entries generated prior to the logging machine's compromise impossible for the attacker to read, and also impossible to modify or destroy undetectably.

A cryptographic coprocessor is described for certifying outcomes of software programs. The system for certifying and authenticating outputs allows a third party who trusts the secure components of the system to verify that a specied program actually executed and produced a claimed output.

In this paper, we develop methods for constructing vote-buying/coercion attacks on end-to-end voting systems, and describe vote-buying/coercion attacks on three proposed end-to-end voting systems: Punchscan, Pret-a-voter, and ThreeBallot. We also demonstrate a different attack on Punchscan, which could permit corrupt election officials to change votes without detection in some cases. Additionally, we consider some generic attacks on end-to-end voting systems.

The National Institute of Standards and Technology (NIST) opened a public competition on November 2, 2007 to develop a new cryptographic hash algorithm – SHA-3, which will augment the hash algorithms currently specified in the Federal Information Processing Standard (FIPS) 180-3, Secure Hash Standard. The competition was NIST’s response to advances in the cryptanalysis of hash algorithms. NIST received sixty-four submissions in October 2008, and selected fifty-one candidate algorithms as the first-round candidates on December 10, 2008, and fourteen as the second-round candidates on July 24, 2009. One year was allocated for the public review of the second-round candidates. On December 9, 2010, NIST announced five SHA-3 finalists to advance to the third (and final) round of the competition. This report summarizes the evaluation and selection of the five finalists – BLAKE, Grostl, JH, Keccak and Skein.

In this paper we present new attack techniques to analyze the structure of hash functions that are not based on the classical Merkle-Damgard construction. We extend the herding attack to concatenated hashes, and to certain hash functions that process each message block several times. Using this technique, we show a second preimage attack on the folklore "hash-twice" construction which process two concatenated copies of the message. We follow with showing how to apply the herding attack to tree hashes. Finally, we present a new type of attack -- the trojan message attack, which allows for producing second preimages of unknown messages (from a small known space) when they are appended with a fixed suffix.

International audience; We develop a new generic long-message second preimage attack, based on combining the techniques in the second preimage attacks of Dean [8] and Kelsey and Schneier [16] with the herding attack of Kelsey and Kohno [15]. We show that these generic attacks apply to hash functions using the Merkle-Damgård construction with only slightly more work than the previously known attack, but allow enormously more control of the contents of the second preimage found. Additionally, we show that our new attack applies to several hash function constructions which are not vulnerable to the previously known attack, including the dithered hash proposal of Rivest [25], Shoup's UOWHF[26] and the ROX hash construction [2]. We analyze the properties of the dithering sequence used in [25], and develop a time-memory tradeoff which allows us to apply our second preimage attack to a wide range of dithering sequences, including sequences which are much stronger than those in Rivest's proposals. Finally, we show that both the existing second preimage attacks [8, 16] and our new attack can be applied even more efficiently to multiple target messages; in general, given a set of many target messages with a total of 2^R message blocks, these second preimage attacks can find a second preimage for one of those target messages with no more work than would be necessary to find a second preimage for a single target message of 2^R message blocks.

We expand a previous result of Dean [Dea99] to provide a second preimage attack on all n-bit iterated hash functions with Damgard-Merkle strengthening and n-bit intermediate states, allowing a second preimage to be found for a 2k-message-block message with about k × 2n/2+1 + 2n−k+1 work. Using RIPEMD-160 as an example, our attack can find a second preimage for a 260 byte message in about 2106 work, rather than the previously expected 2160 work. We also provide slightly cheaper ways to find multicollisions than the method of Joux [Jou04]. Both of these results are based on expandable messages–patterns for producing messages of varying length, which all collide on the intermediate hash result immediately after processing the message. We provide an algorithm for finding expandable messages for any n-bit hash function built using the Damgard-Merkle construction, which requires only a small multiple of the work done to find a single collision in the hash function.

Helix is a high-speed stream cipher with a built-in MAC functionality. On a Pentium II CPU it is about twice as fast as Rijndael or Twofish, and comparable in speed to RC4. The overhead per encrypted/authenticated message is low, making it suitable for small messages. It is efficient in both hardware and software, and with some pre-computation can effectively switch keys on a per-message basis without additional overhead.

We develop protocols for an authenticated camera that allows people to verify that a given digital image was taken by a specific camera at a specific time and specific place. These protocols require interaction between the camera and base station both before and after a series of images are taken.

We improve the best attack on Rijndael reduced to 6 rounds from complexity 272 to 244. We also present the first known attacks on 7- and 8-round Rijndael. The attacks on 8-round Rijndael work for 192- bit and 256-bit keys. Finally, we discuss the key schedule of Rijndael and describe a related-key attack that can break 9-round Rijndael with 256-bit keys.