Chosen-ciphertext Clustering Attack on CRYSTALS-KYBER using the Side-channel Leakage of Barrett Reduction

This study proposes a chosen-ciphertext side-channel attack against a lattice-based key encapsulation mechanism (KEM), the third-round candidate of the national institute of standards and technology (NIST) standardization project. Unlike existing attacks that target operations such as inverse NTT and message encoding/decoding, we target Barrett Reduction in the decapsulation phase of CRYSTALS-KYBER to obtain a secret key. We show that a sensitive variable-dependent leakage of Barrett Reduction exposes an entire secret key. The results of experiments conducted on the ARM Cortex-M4 microcontroller accomplish a success rate of 100%. We only need six chosen ciphertexts for KYBER512 and KYBER768 and eight chosen ciphertexts for KYBER1024. We also show that the m4 scheme of the pqm4 library, an implementation with the ARM Cortex-M4 specific optimization (typically in assembly), is vulnerable to the proposed attack. In this scheme, six, nine, and twelve chosen ciphertexts are required for KYBER512, KYBER768, and KYBER1024, respectively

Observation of transverse spin Nernst magnetoresistance induced by thermal spin current in ferromagnet/non-magnet bilayers

Electric generation of spin current via spin Hall effect is of great interest as it allows an efficient manipulation of magnetization in spintronic devices. Theoretically, spin current can be also created by a temperature gradient, which is known as spin Nernst effect. Here, we report spin Nernst effect-induced transverse magnetoresistance in ferromagnet (FM)/non-magnetic heavy metal (HM) bilayers. We observe that the magnitude of transverse magnetoresistance (i.e., planar Nernst signal) in FM/HM bilayers is significantly modified by HM and its thickness. This strong dependence of transverse magnetoresistance on HM evidences the spin Nernst effect in HM; the generation of thermally-induced spin current in HM and its subsequent reflection at the FM/HM interface. Our analysis of transverse magnetoresistance shows that the spin Nernst angles of W and Pt have the opposite sign to their spin Hall angles. Moreover, our estimate implies that the magnitude of the spin Nernst angle would be comparable to that of the spin Hall angle, suggesting an efficient generation of spin current by the spin Nernst effect

Bezoar-induced Small Bowel Obstruction

Purpose: The aim of this study was to observe the clinical features of a bezoar-induced small bowel obstruction and to in-vestigate the role of abdominal computed tomography (CT) in establishing the diagnosis. Methods: We retrospectively reviewed 20 cases of bezoar-induced small bowel obstruction in our hospital from 1996 to 2010. Results: Thirteen patients (65%) had a history of abdominal surgery. Nine patients (45%) were diagnosed with a bezoar before surgery, seven patients were diagnosed by using abdominal CT, and two patients were diagnosed with a small bowel series. Abdominal CT was performed in 15 patients, and the diagnostic accuracy was 47 % (7/15). Surgery revealed ten bezoars in the jejunum and 11 in the ileum. Two patients had bezoars found concurrently in the stomach. Spontaneous removal took place in two patients. An enterotomy and bezoar extraction was performed in 15 patients. Fragmentation and milking, a small bowel resection, and a Meckel’s diverticulectomy were performed in one patient each. Early operative treatment was possible (P = 0.036) once the bezoar had been diagnosed by using abdominal CT. There tended to be fewer postoperative complications in patients who were diagnosed with a bezoar by using abdominal CT, but the result was not statistically significant (P = 0.712). Conclusion: A preoperative diagnosis of bezoar-induced small bowel obstruction by using clinical features was difficult. Increased use of abdominal CT led to a more accurate diagnosis and to earlier surgery for bezoar-induced small bowel obstructions, thereby reducing the rate of complications

Non-Profiled Side Channel Attack based on Deep Learning using Picture Trace

In this paper, we suggest a new format for converting side channel traces to fully utilize the deep learning schemes. Due to the fact that many deep learning schemes have been advanced based on MNIST style datasets, we convert from raw-trace based on float or byte data to picture-formatted trace based on position. This is induced that the best performance can be acquired from deep learning schemes. Although the overfitting cannot be avoided in our suggestion, the accuracy for validation outperforms to previous results of side channel analysis based on deep learning. Additionally, we provide a novel criteria for attack success or fail based on statistical confidence level rather than rule of thumb. Even though the data storage is slightly increased, our suggestion can completely be recovered the correct key compared to previous results. Moreover, our suggestion scheme has a lot of potential to improve side channel attack

The possible roles of hyperpolarization-activated cyclic nucleotide channels in regulating pacemaker activity in colonic interstitial cells of Cajal

BACKGROUND: Hyperpolarization-activated cyclic nucleotide (HCN) channels are pacemaker channels that regulate heart rate and neuronal rhythm in spontaneously active cardiac and neuronal cells. Interstitial cells of Cajal (ICCs) are also spontaneously active pacemaker cells in the gastrointestinal tract. Here, we investigated the existence of HCN channel and its role on pacemaker activity in colonic ICCs. METHODS: We performed whole-cell patch clamp, RT-PCR, and Ca(2+)-imaging in cultured ICCs from mouse mid colon. RESULTS: SQ-22536 and dideoxyadenosine (adenylate cyclase inhibitors) decreased the frequency of pacemaker potentials, whereas both rolipram (cAMP-specific phosphodiesterase inhibitor) and cell-permeable 8-bromo-cAMP increased the frequency of pacemaker potentials. CsCl, ZD7288, zatebradine, clonidine (HCN channel blockers), and genistein (a tyrosine kinase inhibitor) suppressed the pacemaker activity. RT-PCR revealed expression of HCN1 and HCN3 channels in c-kit and Ano1 positive colonic ICCs. In recordings of spontaneous intracellular Ca(2+) [Ca(2+)](i) oscillations, rolipram and 8-bromo-cAMP increased [Ca(2+)](i) oscillations, whereas SQ-22536, CsCl, ZD7288, and genistein decreased [Ca(2+)](i) oscillations. CONCLUSIONS: HCN channels in colonic ICCs are tonically activated by basal cAMP production and participate in regulation of pacemaking activity