25 research outputs found
Improvements to RSA key generation and CRT on embedded devices
RSA key generation requires devices to generate large prime numbers. The naĂŻve approach is to generate candidates at random, and then test each one for (probable) primality. However, it is faster to use a sieve method, where the candidates are chosen so as not to be divisible by a list of small prime numbers .
Sieve methods can be somewhat complex and time-consuming, at least by the standards of embedded and hardware implementations, and they can be tricky to defend against side-channel analysis. Here we describe an improvement on Joye et al.\u27s sieve based on the Chinese Remainder Theorem (CRT). We also describe a new sieve method using quadratic residuosity which is simpler and faster than previously known methods, and which can produce values in desired RSA parameter ranges such as with minimal additional work. The same methods can be used to generate strong primes and DSA moduli.
We also demonstrate a technique for RSA private key operations using the Chinese Remainder Theorem (RSA-CRT) without mod . This technique also leads to inversion-free batch RSA and inversion-free RSA mod .
We demonstrate how an embedded device can use our key generation and RSA-CRT techniques to perform RSA efficiently without storing the private key itself: only a symmetric seed and one or two short hints are required
SoC It to EM:ElectroMagnetic Side-Channel Attacks on a Complex System-on-Chip
Increased complexity in modern embedded systems has presented various important challenges with regard to side-channel attacks. In particular, it is common to deploy SoC-based target devices with high clock frequencies in security-critical scenarios; understanding how such features align with techniques more often deployed against simpler devices is vital from both destructive (i.e., attack) and constructive (i.e., evaluation and/or countermeasure) perspectives. In this paper, we investigate electromagnetic-based leakage from three different means of executing cryptographic workloads (including the general purpose ARM core, an on-chip co-processor, and the NEON core) on the AM335x SoC. Our conclusion is that addressing challenges of the type above {\em is} feasible, and that key recovery attacks can be conducted with modest resources
The Passive Journalist: How sources dominate the local news
This study explores which sources are âmakingâ local news and whether these sources are simply indicating the type of news that appears, or are shaping newspaper coverage. It provides an empirical record of the extent to which sources are able to dominate news coverage from which future trends in local journalism can be measured. The type and number of sources used in 2979 sampled news stories in four West Yorkshire papers, representing the three main proprietors of local newspapers in the United Kingdom, were recorded for one month and revealed the relatively narrow range of routine sources; 76 per cent of articles cited only a single source. The analysis indicates that journalists are relying less on their readers for news, and that stories of little consequence are being elevated to significant positions, or are filling news pages at the expense of more important stories. Additionally, the reliance on a single source means that alternative views and perspectives relevant to the readership are being overlooked. Journalists are becoming more passive, mere processors of one-sided information or bland copy dictated by sources. These trends indicate poor journalistic standards and may be exacerbating declining local newspaper sales
Small Screen, Big Tourism: The Role of Popular Korean Television Dramas in South Korean Tourism
This paper examines a popular cultural phenomenon originating in Korea which has assumed significance across Asia and beyond. This âKorean waveâ or Hallyu includes the circulation and consumption of Korean popular television dramas. An exploratory case study approach is presented to provide insights on the relationships between this phenomenon and patterns of tourism in Korea related to the wider concept of screen-tourism. The paper addresses the relative lack of attention to television programming within the film tourism literature, particularly in non-Western and non-English language settings. Some common assumptions in the film tourism literature are challenged here, including: the inter-changeability of large-screen films and programmes produced for the television; and the inter-cultural circulation of film and television programmes as catalysts for tourism. Our findings illustrate that the inter-cultural circulation of Hallyu television dramas, particularly in neighbouring countries in Asia, may be interpreted in relation to theories of cultural proximity. A need to understand the complex patterns and political economy of distribution, circulation and reception of television programmes is also identified. The paper argues for more research that links visitor flows with television audience research and which recognizes the organizational infrastructures that allow media productions to go beyond circulation in domestic TV markets. Professional expertise and networks, transnational business relationships, ownership and national media regulatory regimes are highlighted, as is the extent to which media professionals and organizations connect with the domestic and international tourism sector
âFourth placesâ: the Contemporary Public Settings for Informal Social Interaction among Strangers.
This paper introduces âfourth placesâ as an additional category of informal social settings alongside âthird placesâ (Oldenburg 1989). Through extensive empirical fieldwork on where and how social interaction among strangers occurs in the public and semi-public spaces of a contemporary masterplanned neighbourhood, this paper reveals that âfourth placesâ are closely related to âthird placesâ in terms of social and behavioural characteristics, involving a radical departure from the routines of home and work, inclusivity, and social comfort. However, the activities, users, locations and spatial conditions that support them are very different. They are characterized by âin-betweennessâ in terms of spaces, activities, time and management, as well as a great sense of publicness. This paper will demonstrate that the latter conditions are effective in breaking the âplacelessnessâ and âfortressâ designs of newly designed urban public spaces and that, by doing so, they make âfourth placesâ sociologically more open in order to bring strangers together. The recognition of these findings problematizes well-established urban design theories and redefines several spatial concepts for designing public space. Ultimately, the findings also bring optimism to urban design practice, offering new insights into how to design more lively and inclusive public spaces. Keywords: âFourth placesâ, Informal Public Social Settings, Social Interaction, Strangers, Public Space Design
Improved "Partial Sums"-based Square Attack on AES
The Square attack as a means of attacking reduced round variants of AES was described in the initial description of the Rijndael block cipher. This attack can be applied to AES, with a relatively small number of chosen plaintext-ciphertext pairs, reduced to less than six rounds in the case of AES-128 and seven rounds otherwise and several extensions to this attack have been described in the literature. In this paper we describe new variants of these attacks that have a smaller time complexity than those present in the literature. Specifically, we demonstrate that the quantity of chosen plaintext-ciphertext pairs can be halved producing the same reduction in the time complexity. We also demonstrate that the time complexity can be halved again for attacks applied to AES-128 and reduced by a smaller factor for attacks applied to AES-192. This is achieved by eliminating hypotheses on-the-fly when bytes in consecutive subkeys are related because of the key schedule
Practical Complexity Differential Cryptanalysis and Fault Analysis of AES
This paper presents a survey of practical complexity differential cryptanalysis of AES and compares this to attacks that have been proposed for differential fault analysis. Naturally, the attacks in each vein of research are applicable in the other but use different models. In this paper we draw from both topics to improve attacks proposed in the literature. We re-evaluate the so-called Square attack and the use of impossible differentials in terms of differential fault analysis using a weaker model than previously considered in the literature. Furthermore, we propose two new attacks applicable to both differential cryptanalysis and differential fault analysis. The first is a differential cryptanalysis of four-round AES based on a differential that occurs with a non-negligible probability. The second is an application of the Square attack to a five-round AES that requires ciphertexts and a time complexity equivalent to approximately AES encryptions
Using Templates to Distinguish Multiplications from Squaring Operations
Since side channel analysis was introduced as a method to recover secret information from an otherwise secure cryptosystem, many countermeasures have been proposed to prevent leakage from secure devices. Among these countermeasures is side channel atomicity that makes operations indistinguishable using side channel analysis. In this paper we present practical results of an attack on RSA signature generation, protected in this manner, based on the expected difference in Hamming weight between the result of a multiplication and a squaring operation. This work presents the first attack that we are aware of where template analysis can be used without requiring an open device to characterize an implementation of a given cryptographic algorithm. Moreover, an attacker does not need to know the plaintexts being operated on and, therefore, blinding and padding countermeasures applied to the plaintext do not hinder the attack in any way