Ashok Kumar Das

International Institute of Information Technology, Hyderabad, Bhaganagar, Andhra Pradesh, India

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Publications (65)77.94 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Advancement in communication technology provides a scalable platform for various services, where a remote user can access the server from anywhere without moving from its place. It provides a unique opportunity for online services such that a user does not need to be physically present at the service center. These services adopt authentication and key agreement protocols in order to ensure authorized and secure access to the resources. Most of the authentication schemes proposed in the literature support a single-server environment, where the user has to register with each server. If a user wishes to access multiple application servers, he/she requires to register with each server. The multi-server authentication introduces a scalable platform such that a user can interact with any server using single registration. Recently, Chuang and Chen proposed an efficient multi-server authenticated key agreement scheme based on a user’s password and biometrics (Chuang and Chen, 2014). Their scheme is a lightweight, which requires the computation of only hash functions. In this paper, we first analyze Chuang and Chen’s scheme and then identify that their scheme does not resist stolen smart card attack which causes the user’s impersonation attack and server spoofing attack. We also show that their scheme fails to protect denial-of-service attack. We aim to propose an efficient improvement on Chuang and Chen’s scheme to overcome the weaknesses of their scheme, while also retaining the original merits of their scheme. Through the rigorous informal and formal security analysis, we show that our scheme is secure against various known attacks including the attacks found in Chuang and Chen’s scheme. Furthermore, we simulate our scheme for the formal security verification using the widely-accepted AVISPA (Automated Validation of Internet Security Protocols and Applications) tool and show that our scheme is secure against the replay and man-in-the-middle attacks. In addition, our scheme is comparable in terms of the communication and computational overheads with Chuang and Chen’s scheme and other related existing schemes.
    Expert Systems with Applications 12/2014; 41(18):8129–8143. · 1.97 Impact Factor
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    ABSTRACT: Metformin is an oral antidiabetic drug, commonly used for treating type 2 diabetes (T2DM) patients. It is transported into the hepatocyte by polyspecific organic cation transporter 1 which is encoded by the gene SLC22A1. It has been hypothesized that genetic variations of SLC22A1 gene will influence interindividual variation in glucose lowering efficacy of metformin. Previous studies have demonstrated this in other populations with conflicting results, but it remains to be elucidated in Indian population. Henceforth, the objective of the study was to evaluate the impact of SLC22A1 rs622342 gene polymorphism on the clinical efficacy of metformin in South Indian T2DM patients. A total of 122 newly detected, treatment naive T2DM patients of either sex were included in this study. The patients were started on metformin monotherapy and followed up for 12 weeks. Genotype was determined using qRT-PCR. Before and after treatment with metformin, body mass index (BMI), serum lipid profile, glycated hemoglobin (HbA1c), fasting & postprandial glucose level, and blood pressure (BP) were measured. The study cohort mean age was 49.57 ± 9.88yrs. Of the 122 T2DM patients, 93 were classified as responders and 29 as non-responders based on fall in HbA1c levels. Interestingly, carriers of one variant allele ‘C’ (AC) of rs622342 polymorphism were less among the responders than those who did not (44.8% vs. 22.6%). On the contrary, patients with two copies of allele ‘A’ (AA) had 5.6 times greater chance of responding to metformin treatment. A similar trend was observed when the proportion was analyzed under different genetic models (OR 3.85, 95% CI 1.61-9.19 for dominant; OR 3.56, 95% CI 0.83-15.26 for recessive; 55.1% vs. 77.4%; OR 2.78, 95% CI 1.15-6.70 for over-dominant and OR 4.10, 1.78-9.43 for additive). Further, metformin showed significant beneficial effects on BMI, HbA1c, FPG, PPG, lipid parameters and BP. These data suggest that the allele and genotypes of SLC22A1 rs622342 gene polymorphism were associated with the therapeutic efficacy of metformin in South Indian patients with T2DM.
    Clinical and Experimental Medicine 11/2014; · 2.82 Impact Factor
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    Jayakrushna Sahoo, Ashok Kumar Das, A. Goswami
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    ABSTRACT: Traditional association rule mining based on the support-confidence framework provides the objective measure of the rules that are of interest to users. However, it does not reflect the utility of the rules. To extract non-redundant association rules in support-confidence framework frequent closed itemsets and their generators play an important role. To extract non-redundant association rules among high utility itemsets, high utility closed itemsets (HUCI) and their generators should be extracted in order to apply traditional support-confidence framework. However, no efficient method exists at present for mining HUCIs with their generators. This paper addresses this issue. A post-processing algorithm, called the HUCI-Miner, is proposed to mine HUCIs with their generators. The proposed algorithm is implemented using both synthetic and real datasets.
    10/2014;
  • Santanu Chatterjee, Ashok Kumar Das
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    ABSTRACT: For critical applications, real-time data access is essential from the nodes inside a wireless sensor network (WSN). Only the authorized users with unique access privilege should access the specific, but not all, sensing information gathered by the cluster heads in a hierarchical WSNs. Access rights for the correct information and resources for different services from the cluster heads to the genuine users can be provided with the help of efficient user access control mechanisms. In this paper, we propose a new user access control scheme with attribute-based encryption using elliptic curve cryptography in hierarchical WSNs. In attribute-based encryption, the ciphertexts are labeled with sets of attributes and secret keys of the users that are associated with their own access structures. The authorized users with the relevant set of attributes can able to decrypt the encrypted message coming from the cluster heads. Our scheme provides high security. Moreover, our scheme is efficient as compared with those for other existing user access control schemes. Through both the formal and informal security analysis, we show that our scheme has the ability to tolerate different known attacks required for a user access control designed for WSNs. Furthermore, we simulate our scheme for the formal security verification using the widely-accepted automated validation of Internet security protocols and applications tool. The simulation results demonstrate that our scheme is secure. Copyright © 2014 John Wiley & Sons, Ltd.
    Security and Communication Networks 10/2014; · 0.43 Impact Factor
  • Vanga Odelu, Ashok Kumar Das, Adrijit Goswami
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    ABSTRACT: A user authentication in the distributed computer networks (DCNs) plays a crucial rule to verify whether the user is a legal user and can therefore be granted access to the requested services to that user. In recent years, several RSA-based single sign-on mechanisms have been proposed in DCNs. However, most of them cannot preserve the user anonymity when possible attacks occur. The user devices are usually battery limited (e.g., cellular phones) and the elliptic-curve cryptosystem is much efficient than RSA cryptosystem for the battery-limited devices. In this paper, we aim to propose a new secure elliptic-curve cryptosystem-based single sign-on mechanism for user authentication and key establishment for the secure communications in a DCNs using biometric-based smart card. In our scheme, a user only needs to remember a private password and his or her selected unique identity to authenticate and agree on a high-entropy cryptographic one-time session key with a provider to communicate over untrusted public networks. Through formal and informal security analysis, we show that our scheme prevents other known possible attacks. In addition, we perform simulation on our scheme for the formal security verification using the widely-accepted Automated Validation of Internet Security Protocols and Applications tool. The simulation results ensure that our scheme is secure against replay and man-in-the-middle attacks. Furthermore, our scheme provides high security along with lower computational cost and communication cost, and as a result, our scheme is much suitable for the battery-limited devices as compared to other related RSA-based schemes. Copyright © 2014 John Wiley & Sons, Ltd.
    Security and Communication Networks 10/2014; · 0.43 Impact Factor
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    ABSTRACT: High blood pressure (BP) is a known risk factor for cardiovascular disease morbidity. Considering the growing evidence of nonpharmacological interventions in the management of high BP, we designed a randomized, parallel active-controlled study on the effect of yoga and standard lifestyle modification (LSM) on BP and heart rate in individuals with prehypertension (systolic BP 120-139 mm Hg and/or diastolic BP 80-89 mm Hg). Volunteers (20-60 years) of both genders without any known cardiovascular disease were randomized into either LSM group (n=92) or LSM+yoga group (n=92). Before the intervention, age, waist circumference, physical activity, BP and fasting plasma glucose and lipids were comparable between the groups. After 12 weeks of intervention, we observed a significant reduction in the BP and heart rate in both the groups. Further, the reduction in systolic BP was significantly more in LSM+yoga group (6 mm Hg) as compared with LSM group (4 mm Hg). In addition, 13 prehypertensives became normotensives in LSM+yoga group and four in LSM group. The results indicate efficacy of nonpharmacological intervention and the additional benefit of yoga to standard LSM. Further research in this field may add to the level of evidence on the benefit of yoga, in the reduction of BP in high BP subjects, in the scientific literature.Hypertension Research advance online publication, 4 September 2014; doi:10.1038/hr.2014.126.
    Hypertension Research 09/2014; · 2.94 Impact Factor
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    ABSTRACT: Congenital hyperinsulinemic hypoglycemia (HI) is a heterogeneous genetic disorder of insulin secretion characterized by persistent hypoglycemia, most commonly associated with inactivating mutations of the β-cell ATP-sensitive K+ channel (KATP channel) genes ABCC8 (encoding SUR1) and KCNJ11(encoding Kir6.2). This study aimed to screen the mutations in the genes associated with congenital HI in Asian Indian children. Recessive mutations of these genes cause hyperinsulinism that is unresponsive to treatment with channel agonists like diazoxide. Dominant KATP mutations have been associated with diazoxide-responsive disease. The KCNJ11, ABCC8, GCK, HNF4A, and GLUD1 genes were analyzed by sequence analysis in 22 children with congenital HI. We found 10 novel mutations (c.1delA, c.61delG, c.267delT, c.619–629delCCCGAGGACCT, Gln444*, Leu724Pro, Ala847Thr, Trp898*, IVS30–2A>C, and Leu1454Arg) and two known mutations (Gly111Arg and Arg598*) in the ABCC8 gene. This study describes novel and known ABCC8 gene mutations in children with congenital HI. This is the first large genetic screening study on HI in India and our results will help clinicians in providing optimal treatment for patients with hyperinsulinemia and in assisting affected families with genetic counseling.
    Annals of Human Genetics 09/2014; 78(5). · 1.93 Impact Factor
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    ABSTRACT: Abstract Aims: This study estimated the levels of glycemic control among subjects with self-reported diabetes in urban and rural areas of four regions in India. Research Design and Methods: Phase I of the Indian Council of Medical Research-India Diabetes (ICMR-INDIAB) Study was conducted in a representative population of three states of India (Tamil Nadu, Maharashtra, and Jharkhand) and one Union Territory (Chandigarh) and covering a population of 213 million people. Using a stratified multistage sampling design, individuals ≥20 years of age were recruited. Glycemic control among subjects with self-reported diabetes was assessed by measurement of glycated hemoglobin (HbA1c), estimated by the Variant™ II Turbo method (Bio-Rad, Hercules, CA). Results: Among the 14,277 participants in Phase I of INDIAB, there were 480 subjects with self-reported diabetes (254 urban and 226 rural). The mean HbA1c levels were highest in Chandigarh (9.1±2.3%), followed by Tamil Nadu (8.2±2.0%), Jharkhand (8.2±2.4%), and Maharashtra (8.0±2.1%). Good glycemic control (HbA1c <7%) was observed only in 31.1% of urban and 30.8% of rural subjects. Only 22.4% of urban and 15.4% of rural subjects had reported having checked their HbA1c in the past year. Multiple logistic regression analysis revealed younger age, duration of diabetes, insulin use, and high triglyceride levels to be significantly associated with poor glycemic control. Conclusions: The level of glycemic control among subjects with self-reported diabetes in India is poor. Urgent action is needed to remedy the situation.
    Diabetes Technology &amp Therapeutics 08/2014; · 2.29 Impact Factor
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    ABSTRACT: Tumoral calcinosis is a disorder of phosphate metabolism characterized by ectopic calcification around major joints. Surgery is the current treatment of choice, but a suboptimal choice in recurrent and multicentric lesions.
    Indian journal of endocrinology and metabolism. 07/2014; 18(4):521-5.
  • Vanga Odelu, Ashok Kumar Das, Adrijit Goswami
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    ABSTRACT: Lo et al. (2011) proposed an efficient key assignment scheme for access control in a large leaf class hierarchy where the alternations in leaf classes are more frequent than in non-leaf classes in the hierarchy. Their scheme is based on the public-key cryptosystem and hash function where operations like modular exponentiations are very much costly compared to symmetric-key encryptions and decryptions, and hash computations. Their scheme performs better than the previously proposed schemes. However, in this paper, we show that Lo et al.’s scheme fails to preserve the forward security property where a security class CxCx can also derive the secret keys of its successor classes CjCj’s even after deleting the security class CxCx from the hierarchy. We aim to propose a new key management scheme for dynamic access control in a large leaf class hierarchy, which makes use of symmetric-key cryptosystem and one-way hash function. We show that our scheme requires significantly less storage and computational overheads as compared to Lo et al.’s scheme and other related schemes. Through the informal and formal security analysis, we further show that our scheme is secure against all possible attacks including the forward security. In addition, our scheme supports efficiently dynamic access control problems compared to Lo et al.’s scheme and other related schemes. Thus, higher security along with low storage and computational costs make our scheme more suitable for practical applications compared to other schemes.
    Information Sciences 06/2014; 269:270–285. · 3.89 Impact Factor
  • Ashok Kumar Das, Adrijit Goswami
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    ABSTRACT: Recently, Awasthi and Srivastava proposed a novel biometric remote user authentication scheme for the telecare medicine information system (TMIS) with nonce. Their scheme is very efficient as it is based on efficient chaotic one-way hash function and bitwise XOR operations. In this paper, we first analyze Awasthi-Srivastava’s scheme and then show that their scheme has several drawbacks: (1) incorrect password change phase, (2) fails to preserve user anonymity property, (3) fails to establish a secret session key beween a legal user and the server, (4) fails to protect strong replay attack, and (5) lacks rigorous formal security analysis. We then a propose a novel and secure biometric-based remote user authentication scheme in order to withstand the security flaw found in Awasthi-Srivastava’s scheme and enhance the features required for an idle user authentication scheme. Through the rigorous informal and formal security analysis, we show that our scheme is secure against possible known attacks. In addition, we simulate our scheme for the formal security verification using the widely-accepted AVISPA (Automated Validation of Internet Security Protocols and Applications) tool and show that our scheme is secure against passive and active attacks, including the replay and man-in-the-middle attacks. Our scheme is also efficient as compared to Awasthi-Srivastava’s scheme.
    Journal of Medical Systems 06/2014; 38(6). · 1.37 Impact Factor
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    ABSTRACT: To study the pattern and prevalence of dyslipidemia in a large representative sample of four selected regions in India. Phase I of the Indian Council of Medical Research-India Diabetes (ICMR-INDIAB) study was conducted in a representative population of three states of India [Tamil Nadu, Maharashtra and Jharkhand] and one Union Territory [Chandigarh], and covered a population of 213 million people using stratified multistage sampling design to recruit individuals ≥20 years of age. All the study subjects (n = 16,607) underwent anthropometric measurements and oral glucose tolerance tests were done using capillary blood (except in self-reported diabetes). In addition, in every 5th subject (n = 2042), a fasting venous sample was collected and assayed for lipids. Dyslipidemia was diagnosed using National Cholesterol Education Programme (NCEP) guidelines. Of the subjects studied, 13.9% had hypercholesterolemia, 29.5% had hypertriglyceridemia, 72.3% had low HDL-C, 11.8% had high LDL-C levels and 79% had abnormalities in one of the lipid parameters. Regional disparity exists with the highest rates of hypercholesterolemia observed in Tamilnadu (18.3%), highest rates of hypertriglyceridemia in Chandigarh (38.6%), highest rates of low HDL-C in Jharkhand (76.8%) and highest rates of high LDL-C in Tamilnadu (15.8%). Except for low HDL-C and in the state of Maharashtra, in all other states, urban residents had the highest prevalence of lipid abnormalities compared to rural residents. Low HDL-C was the most common lipid abnormality (72.3%) in all the four regions studied; in 44.9% of subjects, it was present as an isolated abnormality. Common significant risk factors for dyslipidemia included obesity, diabetes, and dysglycemia. The prevalence of dyslipidemia is very high in India, which calls for urgent lifestyle intervention strategies to prevent and manage this important cardiovascular risk factor.
    PLoS ONE 05/2014; 9(5):e96808. · 3.53 Impact Factor
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    ABSTRACT: DiabCare India 2011 was a cross-sectional study in patients with diabetes mellitus, undertaken to investigate the relationship between diabetes control, management and complications in a subset of urban Indian diabetes patients treated at referral diabetes care centres in India.
    Indian journal of endocrinology and metabolism. 05/2014; 18(3):370-8.
  • Jayakrushna Sahoo, Ashok Kumar Das, A. Goswami
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    ABSTRACT: Association rule mining among itemsets is a fundamental task and is of great importance in many data mining applications including attacks in network data, stock market, financial applications, bioinformatics to find genetic disorders, etc. However, association rule extraction from a reasonable-sized database produces a large number of rules. As a result, many of them are redundant to other rules, and they are practically useless. To overcome this issue, methods for mining non-redundant rules are essentially required. To address such problem, we initially propose a definition for redundancy in sense of minimal knowledge and then a compact representation of non-redundant association rules which we call as compact informative generic basis. We also provide an improved version of the existing DCI_CLOSED algorithm (DCI_PLUS) to find out the frequent closed itemsets (FCI) with their minimal representative generators in combination with BitTable which represents a compact database form in a single scan of the original database. We further introduce an algorithm for constructing the compact informative generic basis from the FCI and their generators in an efficient way. We finally present an inference mechanism in which all association rules can be generated without accessing the database. Experiments are performed on the proposed method. The experimental results show that the proposed method outperforms the other existing related methods.
    Knowledge and Information Systems 02/2014; · 2.64 Impact Factor
  • Diabetes care 02/2014; 37(2):e38. · 7.74 Impact Factor
  • Ashok Kumar Das, Adrijit Goswami, Vanga Odelu
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    ABSTRACT: The hierarchical cryptographic key assignment is used to assign cryptographic keys to a set of partially ordered security classes so that the user in a higher security class can derive the cryptographic secret keys of the other users in a lower security class. In this paper, we propose a practical solution for dynamic access problems in a user hierarchy, which uses the polynomial interpolation and hash function. When compared with other related recent existing access control schemes, in our scheme the computational complexity and the required storage space are significantly reduced. In addition, our scheme provides provable security. Furthermore, our scheme is easy to implement and therefore, it is more suitable for practical applications.
    International Journal of Communication Networks and Distributed Systems 02/2014; 12(2):129-151.
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    ABSTRACT: In 2012, Das et al. proposed a new password-based remote user authentication scheme in hierarchical wireless sensor networks (HWSNs). The proposed scheme achieves better security and efficiency as compared to those for other existing password-based schemes proposed in HWSNs. In this paper, we first analyse Das et al.'s scheme for formal security under the random oracle models to show their scheme is secure. Furthermore, we simulate this proposed scheme for formal security verification using the widely-accepted automated validation of internet security protocols and applications (AVISPA) tool. Using the AVISPA model checkers, we show that Das et al.'s scheme is also secure against possible passive and active attacks, including the replay and man-in-the-middle attacks. In addition, we also simulate the existing password-based schemes for formal security verification using AVISPA tool and provide a comparison among Das et al.'s scheme and other schemes. It is shown that Das et al.'s scheme outperforms other existing approaches.
    Int. J. of Trust Management in Computing and Communications. 01/2014; 2(1):78 - 102.
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    Ashok Kumar Das, Vanga Odelu, Adrijit Goswami
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    ABSTRACT: In a remote user authentication scheme, a remote server verifies whether a login user is genuine and trustworthy, and also for mutual authentication purpose a login user validates whether the remote server is genuine and trustworthy. Several remote user authentication schemes using the password, the biometrics, and the smart card have been proposed in the literature. However, most schemes proposed in the literature are either computationally expensive or insecure against several known attacks. In this paper, we aim to propose a new robust and effective password-based remote user authentication scheme using smart card. Our scheme is efficient, because our scheme uses only efficient one-way hash function and bitwise XOR operations. Through the rigorous informal and formal security analysis, we show that our scheme is secure against possible known attacks. We perform the simulation for the formal security analysis using the widely accepted AVISPA (Automated Validation Internet Security Protocols and Applications) tool to ensure that our scheme is secure against passive and active attacks. Furthermore, our scheme supports efficiently the password change phase always locally without contacting the remote server and correctly. In addition, our scheme performs significantly better than other existing schemes in terms of communication, computational overheads, security, and features provided by our scheme.
    TheScientificWorldJournal. 01/2014; 2014:719470.
  • Siddharth N Shah, Ashok Kumar Das
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    ABSTRACT: Ideally, the insulin therapy must aim at the creation of a near normal glycaemic profile without the barriers of unacceptable weight gain or hypoglycaemia. Provision of a flexible insulin regimen would further enhance adherence to the prescribed therapy and positively impact glycaemic control. Insulin degludec addresses many of the aspirations of ideal basal insulin. Long duration of action, flat pharmacodynamic profile, low day-to-day variability translate into benefits of predictable glucose excursions, lower risk of hypoglycaemia at same glycaemic level and effective glycaemic with one daily injection in individuals. In conclusion, insulin degludec represents an important advancement in the treatment of type 1 and 2 diabetes.
    The Journal of the Association of Physicians of India 01/2014; 62(1 Suppl):5-9.
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    ABSTRACT: Context:We report a case of tumor induced osteomalacia with evidence of synchronous multifocal FGF23 production.Objective:The aim is to present a case of tumor induced osteomalacia and to highlight the fact that incomplete removal of multifocal FGF23 producing tumors, which are not entirely picked up by functional imaging could be the cause of failure of treatment.Setting:Department of Endocrinology of a tertiary care center in IndiaPatient:We report the case of a 42 year old male with tumor induced osteomalaciaIntervention:We treated the tumor induced osteomalacia with staged surgery of the two tumors. The FDG-avid lesion (considered the sole culprit lesion after functional imaging) was resected first followed by the non-FDG-avid lesion. The sequential removal of both the tumors resulted in complete cure.Results:The patient had hypophosphatemia and hyperphosphaturia. C-terminal FGF23 level was elevated. PET- CT showed two lesions -one, FDG-avid in the right leg and other, a non-avid lesion in the left thigh. After removal of the FDG-avid lesion, the hypophosphatemia persisted and the FGF23 level showed only modest reduction. He had complete clinical and biochemical resolution only after removal of the second non-FDG-avid tumor.Conclusions:We present the case of a tumor induced osteomalacia whose biochemical parameters did not improve after removal of the FDG-avid tumor initially. The possibility of multifocal FGF23 production was considered and the second, non-FDG-avid lesion was resected, which resulted in complete cure. Thorough clinical examination and meticulous follow up with documentation of the biochemical resolution is necessary for management of all patients with this rare disorder.
    The Journal of Clinical Endocrinology and Metabolism 12/2013; · 6.31 Impact Factor

Publication Stats

212 Citations
77.94 Total Impact Points

Institutions

  • 2014
    • International Institute of Information Technology, Hyderabad
      Bhaganagar, Andhra Pradesh, India
    • Biomedical Informatics Centre
      Chandigarh, Chandīgarh, India
  • 2012–2014
    • International Institute of Information Technology
      Poona, Mahārāshtra, India
  • 1986–2014
    • Jawaharlal Institute of Postgraduate Medical Education & Research
      • • Department of Endocrinolgy
      • • Department of Medicine
      Pondichéry, Pondicherry, India
  • 2010–2012
    • Jothydev's Diabetes and Research Center
      Thrissur, Kerala, India
  • 2011
    • Centre for IT Education
      Bhubaneswar, Orissa, India
    • Bhatia Hospital
      Mumbai, Mahārāshtra, India
    • International Institute of Information Technology, Bhubaneswar
      • Department of Computer Science and Engineering
      Bhubaneswar, Orissa, India
  • 2005–2007
    • IIT Kharagpur
      • Department of Computer Science & Engineering
      Khargpur, Bengal, India