Search

This study presents a simplified structure of bit parallel systolic multiplier over Galois fields (GFs) over the set GF(2m) suitable for cryptographic hardware implementation. A redundant standard basis representation with the irreducible all one polynomial is considered. The systolic multiplier consists of (m+1)2 identical cells, each consisting of one two-input AND gate, one two-input XOR gate and two one-bit latches. This architecture is well suited to very large-scale integration implementation because of its regularity modular structure and unidirectional data flow. The proposed multipliers have clock cycle latency of (m+1). This architecture has a total reduction of m2 D-flip-flops compared to earlier bit parallel systolic multiplication architecture. As the finite-field multiplier is one of the complex blocks in cryptographic hardware and need secure testability to avoid unwanted access into the on-chip security blocks, the authors also introduce an on-chip testing scheme. The authors propose a test generation technique for detecting stuck-at fault (SAF), transition delay fault (TDF), stuck-open fault (SOF) and path delay faults (PDFs) at the gate and cell level in the systolic architecture. The authors also show that realistic sequential cell fault can be detected only by 12 single input change test vectors in the complete systolic multiplier over GF(2m). The proposed technique derives test vectors from the cell expressions of systolic multipliers without any requirement of an automatic test pattern generation tool. The complete systolic architecture is C-testable for SAF, TDF, SOF and PDF with only 12 constant tests. The test vectors are independent of the multiplier size. The test set provides 100% single SAF, TDF, SOF and PDF coverage. [ABSTRACT FROM AUTHOR]

In deep-submicron very-large-scale integration (VLSI) systems, efficient circuit testability is one of the most demanding requirements. An automatic synthesis technique for designing efficiently testable logic circuits is one of the ways to tackle the problem. To this end, this study introduces the generalised theory and a new fast efficient graph-based decomposition technique for the functions over finite fields defined over the set GF(N), where N is a power of a prime number, which utilises the data structure of the multiple-output decision diagrams. In particular, the proposed technique can decompose any N valued arbitrary function over the fields conjunctively and disjunctively. The proposed technique is capable of generating testable circuits. The experimental results show that the proposed method is more economical in terms of literal count compared to the existing approaches. Furthermore, the authors have shown that the basic block can be tested with only eight test vectors. [ABSTRACT FROM AUTHOR]

Motivated by the problems associated with soft errors in digital circuits and fault-related attacks in cryptographic hardware, a systematic method for designing single error correcting multiplier circuits is presented for finite fields or Galois fields over GF(2m). Multiple parity predictions to correct single errors based on the Hamming principles are used. The expressions for the parity prediction are derived from the input operands, and are based on the primitive polynomials of the fields. This technique, when compared with existing ones, gives better performance. It is shown that single error correction (SEC) multipliers over GF(2m) require slightly over 100% extra hardware, whereas with the traditional SEC techniques, this figure is more than 200%. Since single bit internal faults can cause multiple faults in the outputs, this has also been addressed here by using multiple Hamming codes with optimised hardware. [ABSTRACT FROM AUTHOR]

This paper presents an efficient technique for synthesis and optimization of the polynomials over GF(2m), where m is a nonzero positive integer. The technique is based on a graph-based decomposition and factorization of the polynomials, followed by efficient network factorization and optimization. A technique for efficiently computing the coefficients of the polynomials over GF(pm), where p is a prime number, is first presented. The coefficients are stored as polynomial graphs over GF(pm). The synthesis and optimization is initiated from this graph-based representation. The technique has been applied to minimize multipliers over the fields GF(2κ ), where k = 2,..., 8, generated with all the 51 primitive polynomials in the 0.18-/~m CMOS technology with the help of the Synopsys design compiler. It has also been applied to minimize combinational exponentiation circuits, parallel integer adders and multipliers, and other multivariate bit- as well as word-level polynomials. The experimental results suggest that the proposed technique can reduce area, delay, and power by significant amounts. We also observed that the technique is capable of producing 100% testable circuits for stuck-at faults. [ABSTRACT FROM AUTHOR]

Background: Colonoscopy is an important procedure in the management of colorectal diseases. During a colonoscopy, one can visualize the mucosa of the large bowel and perform therapeutic procedures., Aim: The aim of this study is to review the indications and findings of colonoscopy in our center. Data on age, gender, indications, and findings at endoscopy were extracted from the endoscopy unit register., Patients and Methods: The study is a retrospective descriptive one and included all patients who underwent colonoscopy between June 2017 to December 2019 at the endoscopy unit of Ahmadu Bello University Teaching Hospital (ABUTH), Zaria. Data on age, gender, indications, and findings at endoscopy were extracted from the endoscopy unit register. The data obtained were analyzed using the Statistical Package for the Social Sciences (SPSS) statistical software version 20., Results: One hundred and twenty-five patients had a colonoscopy during the period under review with a male to female ratio of 1.9:1. The age range of the patients was 3 to 85 years and the mean age was 46.7 ± 16.7 The most common indications for colonoscopy in our center were lower gastrointestinal bleeding (40 (32%)), followed by suspected colonic tumors (37 (29.6%)), and hemorrhoids (18 (14.4%)). The commonest findings were hemorrhoids (50 (40%)), colonic tumors (25 (20%)), and colitis (21 (16.8%))., Conclusion: A colonoscopy is an effective tool in the management of colorectal diseases. Lower gastrointestinal bleeding was the commonest indication for colonoscopy in our center and hemorrhoids and colorectal tumors were the commonest findings., Competing Interests: None

Background: Upper gastrointestinal bleeding (UGIB) is a common medical emergency that can result in significant morbidity and mortality., Aim: The aim of this study was to determine the demographic profile and etiology of UGIB in patients seen at Ahmadu Bello University Teaching Hospital (ABUTH), Zaria, North-Western Nigeria., Subjects and Methods: This descriptive retrospective study was carried out at the Gastroenterology Unit of ABUTH Zaria. Data of patients referred for upper gastrointestinal endoscopy with UGIB from June 2017 to December 2019 were extracted from the endoscopy register and analyzed., Results: One hundred and forty-four patients had upper gastrointestinal (UGI) endoscopy done for UGIB during the period under review. Of these, 105 (72.9%) were males while 39 (27.1%) were females with male-to-female ratio of 2.7:1. The mean age of the patients was 43.5 ± 17.3 and their age ranges from 11 to 89 years. The modal age group was 40-49 years. The most common cause of UGIB was esophageal varices (67 [46.5%]) followed by erosive mucosal diseases: gastritis/duodenitis 43 (29.9%), esophagitis 12 (8.3%). Less common causes were peptic ulcer disease (PUD) in five (3.5%) patients, gastric tumor in two (1.4%), hiatus hernia in one (0.7%), and portal hypertensive gastropathy in one (0.7%). Thirteen patients (9.0%) had normal findings., Conclusion: Esophageal varices are the most common cause of UGIB among our patients and middle-aged male patients were the most commonly affected group., Competing Interests: None