The XTS-AES Disk Encryption Algorithm and the Security of Ciphertext Stealing

Abstract

This paper describes the importance of the XTS-AES encryption mode of operation and concludes with a new proof for the security of ciphertext stealing as used by XTS-AES. The XTS-AES mode is designed for encrypting data stored on hard disks where there is not additional space for an integrity field. Given this lack of space for an integrity field, XTS-AES builds on the security of AES by protecting the storage device from many dictionary and copy/paste attacks. The operation of the XTS mode of AES is defined in the IEEE 1619-2007 standard [3 IEEE Std 1619–2007 . April 18, 2008 . The XTS-AES Tweakable Block Cipher. Institute of Electrical and Electronics Engineers, Inc.  [Google Scholar]], and has been adopted by the U.S. National Institute of Standards and Technology (NIST) as an approved mode of operation under FIPS 140-2 [2 Dworkin , M. December 2009 . NIST SP 800-38E, “Recommendation for Block Cipher Modes of Operation: The XTS-AES Mode for Confidentiality on Storage Devices”.  [Google Scholar]]. XTS-AES builds on the XEX (Xor-Encrypt-Xor) mode originally proposed by Rogaway [8 Rogaway , P. 2004 . Efficient Instantiations of Tweakable Block ciphers and Refinements to Modes OCB and PMAC. Advances in Cryptology–Asiacrypt 2004, Lecture Notes in Computer Science, vol. 3329, Springer-Verlag, pp. 16–31. Available at http://www.cs.ucdavis.edu/rogaway/papers/offsets.pdf (Accessed 6 January 2012) . [Google Scholar]].     

Organizational climate in air traffic control Innovative preparedness for implementation of new technology and organizational development in a rule governed organization

A positive and innovative organizational climate is of great importance in order to manage and adapt to change. Such a climate seldom evolves in organizations closely governed by rules and regulations. Because of ongoing organizational and technical changes within the Swedish Air Navigation Services Provider, a study concerning the organizational climate for changes and innovations was conducted to investigate the organization's capacity to cope with changes. Study locations were the two Swedish main air traffic control centers and parts of the civil aviation administration headquarters. In the study 390 subjects took part and the CCQ questionnaire was used to measure the organizational climate. The results show that the organizational climate is quite positive despite the rule-governed work. The results also show that administrative personnel assess the organizational climate as more positive than operative personnel. Comparisons between management positions did not result in any differences.     

Comparisons of tibial accelerations when walking on a wood composite vs. a concrete mezzanine surface

Mezzanine surfaces can be made from concrete, bar grate, or composite materials. Anecdotal data indicate that mezzanines in distribution centers made from composite materials, due to their increased compliance, may be a more comfortable working surface. Prior research suggested that a measure of tibial shock, peak tibial acceleration, could potentially discriminate the biomechanical differences between these surfaces. The objective of this study was to quantify differences in tibial accelerations as 27 people walked on mezzanines constructed from concrete and a wood composite material. Accelerometers were attached bilaterally to the shins of volunteers, and data were collected as they walked 30.5 m on each surface at their normal walking speed, a faster-than-normal walking speed, and a slower-than-normal walking speed. Peak acceleration values obtained from the leg with the highest values were compared. On average, the peak acceleration values were 5% higher on the concrete mezzanine as compared with the wood composite mezzanine (p = .036). These findings suggest that individuals working on mezzanines in distribution centers constructed from composite surfaces would potentially experience less discomfort associated with long exposure periods on these surfaces.     

Discrepant gender patterns for cyberbullying and traditional bullying – An analysis of Swedish adolescent data

In the wake of the rapid development of modern IT technology, cyberspace bullying has emerged among adolescents. The aim of the present study was to examine gender differences among adolescents involved in traditional bullying and cyberbullying. Cross-sectional data from 2989 Swedish students aged 13–15 were analyzed using logistic regression analysis. The results show discrepant gender patterns of involvement in traditional bullying and cyberbullying. First, although there were only minimal gender differences among traditional victims, girls are more likely than boys to be cybervictims when occasional cyberbullying is used as a cut-off point. Second, whereas boys are more likely to be traditional bullies, girls are as likely as boys to be cyberbullies. In conclusion, compared to traditional bullying, girls are generally more involved in cyberbullying relative to boys. We discuss these results in the light of adolescents’ usage of computerized devices.     

An intercomparison of bio-optical techniques for detecting dominant phytoplankton size class from satellite remote sensing

Satellite remote sensing of ocean colour is the only method currently available for synoptically measuring wide-area properties of ocean ecosystems, such as phytoplankton chlorophyll biomass. Recently, a variety of bio-optical and ecological methods have been established that use satellite data to identify and differentiate between either phytoplankton functional types (PFTs) or phytoplankton size classes (PSCs). In this study, several of these techniques were evaluated against in situ observations to determine their ability to detect dominant phytoplankton size classes (micro-, nano- and picoplankton). The techniques are applied to a 10-year ocean-colour data series from the SeaWiFS satellite sensor and compared with in situ data (6504 samples) from a variety of locations in the global ocean. Results show that spectral-response, ecological and abundance-based approaches can all perform with similar accuracy. Detection of microplankton and picoplankton were generally better than detection of nanoplankton. Abundance-based approaches were shown to provide better spatial retrieval of PSCs. Individual model performance varied according to PSC, input satellite data sources and in situ validation data types. Uncertainty in the comparison procedure and data sources was considered. Improved availability of in situ observations would aid ongoing research in this field.     

The significance of thermal contact resistance in two-layer thermal-barrier-coated turbine vanes

A study was conducted to determine whether the thermal contact resistance (TCR) between layers is important in heat transfer through two-layer plasma-sprayed thermal barrier coatings (TBCs) applied to turbine vanes. The results obtained with a TBC system of an NiCrAlY bond and an yttria-stabilized zirconia ceramic showed that the TCR between the layers was negligible. This result also verified other results obtained with a different coating system of an NiCr bond and a calcia-stabilized zirconia ceramic.     

Pattern of perceived stress and anxiety in pregnancy predicts preterm birth.

Objective: To determine whether the pattern of prenatal stress, as compared to prenatal stress assessed at a single gestational time point, predicts preterm delivery (PTD). Design: Perceived stress and anxiety were assessed in 415 pregnant women at 18-20 and 30-32 weeks' gestation. Main Outcome Measures: Gestational length was determined by last menstrual period and confirmed by early pregnancy ultrasound. Births were categorized as preterm (     

Investigation of Die Stress Profiles During Powder Compaction Using Instrumented Die

The die stress profiles during compaction of commercially pure titanium (Ti) and commercial lubricated iron (Fe) powders were experimentally investigated using an instrumented die. The die was designed to simulate double-action pressing, and a detailed stress profile was measured along the height of the die using multiple custom-made strain gage pins. The stress history shows that residual stress remained in the die in the radial direction after the axial compaction stress was removed from the powder. Also, the stress profile at the maximum axial stress and the residual stress profile were observed to be symmetric across the height of the compact for both powders, but both have a unique shape for each powder. For both the stress profile at the maximum axial stress and the residual stress profile, the unlubricated Ti powder produced a much higher radial stress at the center of the compact with a steep pressure gradient on both top and bottom of the compact, while the lubricated Fe powder produced a rather uniform radial stress distribution along the height of the compact. This article was presented at Materials Science & Technology 2007, Automotive and Ground Vehicles symposium held September 16–20, 2007, in Detroit, MI.