Slide Attacks on a Class of Hash Functions

Abstract. This paper studies the application of slide attacks to hash functions. Slide attacks have mostly been used for block cipher cryptanalysis. But, as shown in the current paper, they also form a potential threat for hash functions, namely for sponge-function like structures. As it turns out, certain constructions for hash-function-based MACs can be vulnerable to forgery and even to key recovery attacks. In other cases, we can at least distinguish a given hash function from a random oracle. To illustrate our results, we describe attacks against the Grindahl-256 and Grindahl-512 hash functions. To the best of our knowledge, this is the first cryptanalytic result on Grindahl-512. Furthermore, we point out a slide-based distinguisher attack on a slightly modified version of RadioGatún. We finally discuss simple countermeasures as a defense against slide attacks. Key words: slide attacks, hash function, Grindahl, RadioGatún, MAC, sponge function.

On some cryptographic properties of Rijndael

We examine diffusion properties of Rijndael which has been selected by US National Institute of Standards and Technology (NIST) for the proposed Advanced Encryption Standard (AES). Since the s-box of Rijndael applies a nonlinear transformation operating on each byte of the intermediate cipher result independently, its characteristics have significant effects on the strength of the entire system. The characteristics of Rijndael's s-box are investigated for the criteria of avalanche, strict avalanche, bit independence, nonlinearity and XOR table distribution. We also evaluate the overall performance for different rounds of Rijndael, and compare it to Safer K-64, in terms of Avalanche Weight Distribution (AWD) criterion

Improved cost function in the design of Boolean functions satisfying multiple criteria

We develop an improved cost function, to be used, in simulated annealing followed by hill-climbing to find Boolean functions satisfying multiple desirable criteria such as high nonlinearity, low autocorrelation, balancedness, and high algebraic degree. Using this cost function that does not necessitate experimental search for parameter tuning, the annealing-based algorithm reaches the desired function profiles more rapidly. Some Boolean functions of eight and nine variables have been found, which are unattained in the computer search based literature, in terms of joint optimization of nonlinearity and autocorrelation. Global characteristics of eight-variable Boolean functions generated by algebraic construction or computer search are compared with respect to the sum-of-squared-error in their squared spectra, which is also proportional to the sum-of-squared-errors in their autocorrelation function, the term 'error' denoting the deviation from bent function characteristics. Preliminary results consisting of cryptographically strong Boolean functions of nine, ten and eleven variables obtained using a three-stage optimization technique are also presented

Nadir görülen senkron tümör birlikteliği, primer yassı hücreli akciğer kanseri ve papiller ürotelyal mesane karsinomu

The incidence of primary bladder and lung cancer occurring together is rare. Here, a case of a man who was diagnosed with end stage lung cancer and early stage bladder cancer was discussed with the interesting aspects. Despite the fact that the patient had a cough, weight loss and dyspnea which are the most common symptoms of lung cancer, hematuria was the main complaint that induced the patient to consult the doctor. The case is valuable for the review of the literature about multiple primary malignancies of squamous cell lung carcinoma and urinary bladder transitional cell carcinoma. It is also important for reminding clinicians to keep in mind that smoking is the most important common predisposing factor for both lung and bladder carcinoma in this case

Light transmittance and surface roughness of a feldspathic ceramic CAD-CAM material as a function of different surface treatments

Background: The aim of the present study was to determine the effect of different surface treatments on light transmission of aesthetic feldspathic ceramics used in CAD-CAM chairside restorations. Methods: Forty eight feldspatic ceramic test specimens were prepared from prefabricated CAD-CAM blocks by using a slow speed diamond saw. Test specimens were prepared and divided into 4 groups (n = 12). In the control group, no surface treatments were applied on the feldspathic ceramic surfaces. In the hydrofluoric acid group, the bonding surfaces of feldspathic ceramics were etched with 9.5 % hydrofluoric acid. In the sandblasting group the feldspathic ceramic surfaces were air-abraded with 30-µm alumium oxide (Al2O3) particles and Er:YAG laser was used to irradiate the ceramic surfaces. The incident light power given by the LED device and the transmitted light power through each ceramic sample was registered using a digital LED radiometer device. Each polymerization light had a light guide with 8-mm-diameter tips. Light transmission of feldspathic ceramic samples was determined by placing it on the radiometer and irradiating the specimen for 10 s at the highest setting for each light polymerization. All specimens were coated with gold using a sputter coater and examined under a field emission scanning electron microscope. Surface roughness measurement each group were evaluated with 3D optical surface and tactile profilometers. Results: One-way ANOVA test results revealed that both surface conditioning method significantly affect the light transmittance (F:412.437; p < 0.001) and the surface roughness values (F:16.386; p < 0.001). Al2O3 and Er-YAG laser application reduced the light transmission significantly (p < 0.05). Conclusions: The laser and Al2O3 applications reduced the light transmission of 1.5 mm thickness feldspathic ceramic material below the value of 400 mW/cm2 which is critical limit for safe polymerization. © 2016 The Author(s)

Color match of a feldspathic ceramic CAD-CAM material for ultrathin laminate veneers as a function of substrate shade, restoration color, and thickness

Statement of problem: The final color of a ceramic restoration, especially an ultrathin veneer, is important, but selecting the correct shade is difficult because the substrate can affect the final color of the restoration. Purpose: The purpose of this in vitro study was to investigate the effect of substrate shade and thickness on the final color of ultrathin laminate veneers milled from feldspathic ceramic and to present a straightforward methodology with which a clinician can visualize the effects of substrate color, ceramic thickness, and prefabricated computer-aided design and computer-aided manufacturing (CAD-CAM) block color on the final color of the restoration. Material and methods: All specimens were fabricated by slicing CAD-CAM feldspathic ceramic material with a precision cutter into 12×10-mm slices of approximately 0.35, 0.55, 0.75, and 1.55 mm in thickness with 10 different colors (0M1-1M1-1M2-2M1-2M2-2M3-3M1-3M2-3M3-4M1). As a background substrate, composite resin disks (12×10×2 mm) were fabricated with different shades (0M1 S, 1M1 S, 2M3 S, 3M2 S, 4M3 S, 5M3 S). The CIELab values of the polished surfaces of each specimen were measured on a background (white or simulated foundation) with a spectrophotometer by a single experienced operator, and color differences (?E) were calculated. Mean ±SD values were calculated and subjected to ANOVA with 2 variables (substrate and ceramic color) (?=.05). Results: Combinations of a lighter substrate shade and a lighter value ceramic restoration and of a darker substrate shade and darker value ceramic restoration only changed the final color of the restoration minimally. Conclusions: The final color of a dental restoration is affected by the thickness of the restoration, the substrate color, and the ceramic color. Lighter and darker substrate colors show more color changes, and thin veneers cannot mask the substrate color. © 2017 Editorial Council for the Journal of Prosthetic Dentistr

Slide Attack on Spectr-H64

We compare one round diffusion characteristics of the block cipher Spectr-H64 to those of AES-Rijndael and Safer K-64, in terms of the Avalanche Weight Distribution (AWD) criterion and observe a weakness in the round transformation of Spectr-H64. We exploit this weakness to break one round of Spectr-H64 extracting half of the key bits, and develop a chosen plaintext slide attack against the overall encryption algorithm, which works for 2(32) elements of the key space (out of 2(256)). We also observe 2(128) weak keys, for which encryption becomes the same function as decryption, and 2(32) fixed points for each weak key