Externally Verifiable Oblivious RAM

We present the idea of externally verifiable oblivious RAM (ORAM). Our goal is to allow a client and server carrying out an ORAM protocol to have disputes adjudicated by a third party, allowing for the enforcement of penalties against an unreliable or malicious server. We give a security definition that guarantees protection not only against a malicious server but also against a client making false accusations. We then give modifications of the Path ORAM and Ring ORAM protocols that meet this security definition. These protocols both have the same asymptotic runtimes as the semi-honest original versions and require the external verifier to be involved only when the client or server deviates from the protocol. Finally, we implement externally verified ORAM, along with an automated cryptocurrency contract to use as the external verifier

CompGC: Efficient Offline/Online Semi-honest Two-party Computation

We introduce a new technique, component-based garbled circuits, for increasing the efficiency of secure two-party computation in the offline/online semi-honest setting. We observe that real-world functions are generally constructed in a modular way, comprising many standard components such as arithmetic operations and other common tasks. Our technique allows circuits for these common tasks to be garbled and shared during an offline phase; once the function to compute is specified, these pre-shared components can be chained together to create a larger garbled circuit. We stress that we do not assume that the function is known during the offline phase --- only that it uses some common, predictable components. We give an implementation, CompGC, of this technique and measure the efficiency gains for various examples. We find that our technique results in roughly an order of magnitude performance improvement over standard garbled circuit-based secure two-party computation

Damage Control: The Untold Story of Venereal Disease in Hamilton, 1900-1950

Venereal disease, now known as sexually-transmitted disease, has a long history of association with humanity. Syphilis, in particular, has attracted enormous debate and controversy ever since the fifteenth century when it erupted in epidemic form in Naples, Italy. This controversy continues not only because there are unresolved questions about where and when syphilis emerged (Powell and Cook 2005), but also because shifting attitudes, perceptions and values toward sexuality affect medical practice, social behaviour, public health practices and the experiences of people afflicted with it (Brandt 1987). This was certainly the case in early twentieth century Canada, the period within which this book is set. The shocking revelation in 1914 that the Canadian Expeditionary Force had the highest level of venereal disease of all the militaryunits serving in Europe was met with surprise, disgust and fear (Cassel 1987). At the time, venereal disease symbolized corrupt sexuality and was understood to be a sign of moral pollution, filth, and disordered sexual practice (Brandt 1987). How could such a disturbing situation have arisen in Canadian society? What did it signal about the state of morality, personal character, and the social order? Who was to blame for this hidden epidemic: irresponsible individuals or deplorable social conditions? What did the unexpectedly high prevalence of diseases transmitted through sexual behaviour mean for the future of the fledgling country? How could the damage wrought by venereal disease be prevented, controlled and cured? Damage Control takes up these questions and tells the untold story of how venereal disease, particularly syphilis, was experienced and understood in Hamilton, Ontario from World War I (WWI) to the mid-twentieth century. Written by fourth-year Honours Anthropology students studying infectious disease at McMaster University, this book is the product of a collaborative writing process. The authors brainstormed the subject matter of the book, then conducted in-depth research in archives in Hamilton and beyond to compile a rich set of newspapers, public health reports, images, and statistics which they shared through a university website. They made stimulating suggestions for each others’ chapters as the writing progressed from the germ of an idea to a fully-developed discussion. In short, everyone contributed to the entirety of the book in an exemplary demonstration of dedicated teamwork and commitment to the project.</p

Duration of androgen deprivation therapy with postoperative radiotherapy for prostate cancer: a comparison of long-course versus short-course androgen deprivation therapy in the RADICALS-HD randomised trial

Background Previous evidence supports androgen deprivation therapy (ADT) with primary radiotherapy as initial treatment for intermediate-risk and high-risk localised prostate cancer. However, the use and optimal duration of ADT with postoperative radiotherapy after radical prostatectomy remains uncertain. Methods RADICALS-HD was a randomised controlled trial of ADT duration within the RADICALS protocol. Here, we report on the comparison of short-course versus long-course ADT. Key eligibility criteria were indication for radiotherapy after previous radical prostatectomy for prostate cancer, prostate-specific antigen less than 5 ng/mL, absence of metastatic disease, and written consent. Participants were randomly assigned (1:1) to add 6 months of ADT (short-course ADT) or 24 months of ADT (long-course ADT) to radiotherapy, using subcutaneous gonadotrophin-releasing hormone analogue (monthly in the short-course ADT group and 3-monthly in the long-course ADT group), daily oral bicalutamide monotherapy 150 mg, or monthly subcutaneous degarelix. Randomisation was done centrally through minimisation with a random element, stratified by Gleason score, positive margins, radiotherapy timing, planned radiotherapy schedule, and planned type of ADT, in a computerised system. The allocated treatment was not masked. The primary outcome measure was metastasis-free survival, defined as metastasis arising from prostate cancer or death from any cause. The comparison had more than 80% power with two-sided α of 5% to detect an absolute increase in 10-year metastasis-free survival from 75% to 81% (hazard ratio [HR] 0·72). Standard time-to-event analyses were used. Analyses followed intention-to-treat principle. The trial is registered with the ISRCTN registry, ISRCTN40814031, and ClinicalTrials.gov , NCT00541047 . Findings Between Jan 30, 2008, and July 7, 2015, 1523 patients (median age 65 years, IQR 60–69) were randomly assigned to receive short-course ADT (n=761) or long-course ADT (n=762) in addition to postoperative radiotherapy at 138 centres in Canada, Denmark, Ireland, and the UK. With a median follow-up of 8·9 years (7·0–10·0), 313 metastasis-free survival events were reported overall (174 in the short-course ADT group and 139 in the long-course ADT group; HR 0·773 [95% CI 0·612–0·975]; p=0·029). 10-year metastasis-free survival was 71·9% (95% CI 67·6–75·7) in the short-course ADT group and 78·1% (74·2–81·5) in the long-course ADT group. Toxicity of grade 3 or higher was reported for 105 (14%) of 753 participants in the short-course ADT group and 142 (19%) of 757 participants in the long-course ADT group (p=0·025), with no treatment-related deaths. Interpretation Compared with adding 6 months of ADT, adding 24 months of ADT improved metastasis-free survival in people receiving postoperative radiotherapy. For individuals who can accept the additional duration of adverse effects, long-course ADT should be offered with postoperative radiotherapy. Funding Cancer Research UK, UK Research and Innovation (formerly Medical Research Council), and Canadian Cancer Society

Externally Verifiable Oblivious RAM

Abstract We present the idea of externally verifiable oblivious RAM (ORAM). Our goal is to allow a client and server carrying out an ORAM protocol to have disputes adjudicated by a third party, allowing for the enforcement of penalties against an unreliable or malicious server. We give a security definition that guarantees protection not only against a malicious server but also against a client making false accusations. We then give modifications of the Path ORAM [15] and Ring ORAM [9] protocols that meet this security definition. These protocols both have the same asymptotic runtimes as the semi-honest original versions and require the external verifier to be involved only when the client or server deviates from the protocol. Finally, we implement externally verified ORAM, along with an automated cryptocurrency contract to use as the external verifier.</jats:p