Browsing by Author "Lemieux, Stephane"

Now showing 1 - 6 of 6
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    Clone resistant mutual authentication for low-cost RFID and contactless credit cards
    (2007) Lemieux, Stephane; Tang, Adrian
    With Radio Frequency Identification (RFID) tags being used to secure contactless credit cards, great benefits but also serious security and information privacy issues have arisen. Recently many attempts have been made to resolve these issues. In particular, attempts have been made to provide a means for authentication between tag and reader. However, none have yet have been able to provide resistance to cloning attacks. Furthermore, authentication on lowest range of low-cost RFID tags, also remains a challenge. We propose a clone resistant, mutual authentication scheme that requires only 32 bits of read write memory, 90 bits of read only memory and can be deployed using as few as 300 logic gates. We also propose a stream cipher with the same memory constraints and magnitude of logic gates. These systems may also be scaled to provide a high level of security, using relatively little computational resources, on larger hardware platforms.
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    Finite exceptional p-groups of small order
    (2007) Lemieux, Stephane
    A finite group is said to be exceptional if its minimal degree of a faithful permutation representation is strictly less than that of one of its factor groups, called a distinguished quotient. It was previously unknown if exceptional p-groups of order less than p 6 existed for p an odd prime. The author proved in his M.Sc thesis that there are none of order ≤p 4 and gave restrictions on the possible existence of distinguished quotients of exceptional groups of order p 5. In this article, an exceptional p-group of order p 5 is exhibited for p any odd prime.
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    Locally finite-indicable groups
    (2007) Lemieux, Stephane
    A group is locally ℜ-indicable if every finitely generated subgroup has a nontrivial homomorphism onto a nontrivial ℜ-group. If ℜ is a quasi-variety, then the class L(ℜ) of locally ℜ-indicable groups coincides with the class N(ℜ) of groups which have normal systems with factors in ℜ. It is not known if ℜ must be a quasi-variety in order for the equality L(ℜ) = N(ℜ) to hold. We show here that if ℑ is the class of all finite groups, which is the union of an ascending sequence of quasi-varieties, then L(ℑ) ≠ N(ℑ). Examples of finitely generated groups in L(ℑ)\ N(ℑ) are also constructed.
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    Novikov groups are right-orderable
    (2022) Lemieux, Stephane
    Novikov groups were introduced as examples of finitely presented groups with unsolvable conjugacy problem. It was Bokut who showed that each Novikov group has a standard basis and thus a solvable word problem. Further, he showed that for every recursively enumerable degree of unsolvability d there is a Novikov group whose conjugacy problem is of degree d. In the present work, we show that Novikov groups are also right-orderable, thus exhibiting the first known examples of finitely presented right-orderable groups with solvable word problem and unsolvable conjugacy problem.
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    Stainless steel electrochemical capacitive microneedle sensors for multiplexed simultaneous measurement of pH, nitrates, and phosphates
    (2022) Mugo, Samuel; Lu, Weihao; Lemieux, Stephane
    Concerns for agri-food safety and environmental management require development of simple to use and cost- and time effective multiplex sensors for point-of-need (PON) chemical analytics by public end-user. Simultaneous detection of nitrates, phosphates, and pH is of importance in soil and water analysis, agriculture, and food quality assessment. This article demonstrates a suite of stainless steel microneedle electrochemical sensors for multiplexed measurement of pH, nitrate, and phosphate using faradaic capacitance derived from cyclic voltammetry as the mode of detection. The multi-target microneedle sensors were fabricated by layer-by-layer (LbL) assembly in a stainless steel hypodermic microneedle substrate. For nitrate sensing, the stainless steel was coated with carbon nanotube/cellulose nanocrystal (CNT)/CNC) decorated with silver nanoparticles (Ag). For pH measurement, the polyaniline (pANI) was coated onto the CNT/CNC@Ag film, while for phosphate detection, the CNT/CNC/Ag @pANI microneedle was further decorated with ammonium molybdenum tetrahydrate (AMT). The microelectrode platforms were characterized by FTIR, Raman, and microscopic techniques. The nitrate- and phosphate-based microneedle electrochemical sensors had excellent selectivity and sensitivity, with a determined limit of detection (LOD) of 0.008 mM and 0.007 mM, respectively. The pH microneedle sensor was responsive to pH in the linear range of 3–10. The three microneedle sensors yielded repeatable results, with a precision ranging from 4.0 to 7.5% RSD over the concentration ranges tested. The inexpensive (~ 1 $ CAD) microneedle sensors were successfully verified for use in quantification of nitrate, pH, and phosphate in brewed black coffee as a real sample. As such, the microneedle sensors are economical devices and show great promise as robust platforms for PON precision chemical analytics.
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    Wearable microneedle dual electrochemical sensor forsimultaneous pH and cortisol detection in sweat
    (2021) Mugo, Samuel; Lu, Weihao; Wood, Marika; Lemieux, Stephane
    We report herewith an inexpensive flexible dual target electrochemical sensor for simultaneous detection of pH and cortisol in human sweat. The sensor was fabricated by printing layer by layer (LbL) on a conductive microneedle polydimethylsiloxane (PDMS) flexible substrate. The dual sensor integrates two detection chambers comprising polyaniline (PANi) and cortisol imprinted poly (glycidylmethacrylate-co ethylene glycol dimethacrylate) (poly (GMA-co-EGDMA)). The dual wearable sensor rapidly (< 1 min) responded linearly to pH in the range of 3–9, while the cortisol sensor chamber had a linear range of 0–100 ng/mL. The cortisol sensing region had an excellent limit of detection (LOD) of 1.4 ± 0.3 ng/mL, with intra-batch reproducibility of 2.4% relative standard deviation (%RSD). The inter-batch precision (%RSD for three different sensors) was determined to be 4.7%. Demonstrating excellent stability and reusability, a single patch of cortisol sensor was used for 15 times over a 30-day period, with minimal change in response. The dual analyte wearable sensors were effective for detection of pH and cortisol in real human sweat.