Prevention of Blackhole Attack in MANET using Certificateless Signature Scheme

Mobile AdHoc Networks (MANETs) are the network of self-configuring nodes. Such nodes communicate through single as well as multi-hop modes without the aid of any centralized administrator or pre-existing network infrastructure. Due to this reason, MANETs have gained a highly significance in modern wireless networking technologies. Such networks are extremely vulnerable to one of the security attack i.e. blackhole attack. It is a malicious node when an attacker is able to send a fake route reply to the originator of a route request packet. Such attackers discard the legitimate packets and replay packets in the whole network thereby adversely affecting network performance. Most of the security protocols for MANET are using bilinear pairing methods to provide security against security attacks and it takes high computing cost for the computation of pairing operations. Nowadays, researchers are using certificate-less signature schemes in distributed environments to provide efficient security. This signature scheme is very popular because it does not use any certificate authority for the management of security certificates. In this paper, we proposed an efficient technique to prevent blackhole attack in MANET using RSA-based certificateless signature scheme without using any bilinear pairing operations. Our scheme provides security against forgery and blackhole attacks and is evaluated under a discrete logarithm problem. Proposed scheme outperforms existing schemes in terms of these metrics viz., throughput, packet delivery ratio, routing overhead and end-to-end delay when we are varying mobility and fixed percentage of malicious nodes. Our proposed scheme not only detects or prevents the blackhole attack but it is also capable to provide important security services viz., integrity, authentication and non-repudiation

Practice of Oral and Maxillofacial Surgery in Nepal: Its Scope and Influencing Factor

Objectives. Oral and maxillofacial surgery is a relatively newer and growing specialty of dentistry in Nepal whose scope is not yet estimated. The objective of this study was to estimate the scope and the factors influencing the scope of oral and maxillofacial surgery in Nepal. Study Design. In this cross-sectional study, all the oral and maxillofacial surgeons who were registered in the Nepalese Association of Oral and Maxillofacial Surgeons (NAOMS) were included (purposive sampling). The structured questionnaires were distributed to them, the collected data were entered in Microsoft excel 2010, and variables were analyzed using descriptive statistics (percentage) by SPSS 16.0. Results. Out of 46 questionnaires distributed, 35 were responded and returned (response rate = 76%). Majority of participants (77.1%) were in 30–39 years of age group. Male to female ratio was 4 : 1. More than half (68.6%) of the participants had practice experience of 20 years. The ratio of the surgeons practiced in Medical/Dental Teaching Hospital to those in Government Hospital was 3 : 1. Sixteen (45.7%) participants practiced in Capital Valley and none in Far-Western Development Region. Traumatology was practiced by thirty-four (97.1%) participants although only twenty-three (65.7%) participants had primary interest in it. Each of oncology, orthognathic surgery, implantology, and cleft lip/palate surgery was performed by <8% of the participants. Common factors influencing the practice were inadequate training (71.4%) and insufficient facilities/infrastructures (45.7%). Conclusion. The scope of oral and maxillofacial surgery is limited in Nepal, and oncology, implantology, cleft lip/palate, and orthognathic surgery have received little attention

Prevention of Blackhole Attack in MANET using Certificateless Signature Scheme

1061-1072Mobile AdHoc Networks (MANETs) are the network of self-configuring nodes. Such nodes communicate through single as well as multi-hop modes without the aid of any centralized administrator or pre-existing network infrastructure. Due to this reason, MANETs have gained a highly significance in modern wireless networking technologies. Such networks are extremely vulnerable to one of the security attack i.e. blackhole attack. It is a malicious node when an attacker is able to send a fake route reply to the originator of a route request packet. Such attackers discard the legitimate packets and replay packets in the whole network thereby adversely affecting network performance. Most of the security protocols for MANET are using bilinear pairing methods to provide security against security attacks and it takes high computing cost for the computation of pairing operations. Nowadays, researchers are using certificate-less signature schemes in distributed environments to provide efficient security. This signature scheme is very popular because it does not use any certificate authority for the management of security certificates. In this paper, we proposed an efficient technique to prevent blackhole attack in MANET using RSA-based certificateless signature scheme without using any bilinear pairing operations. Our scheme provides security against forgery and blackhole attacks and is evaluated under a discrete logarithm problem. Proposed scheme outperforms existing schemes in terms of these metrics viz., throughput, packet delivery ratio, routing overhead and end-to-end delay when we are varying mobility and fixed percentage of malicious nodes. Our proposed scheme not only detects or prevents the blackhole attack but it is also capable to provide important security services viz., integrity, authentication and non-repudiation

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Dentigerous Cystic Changes in the Follicles Associated with Radiographically Normal Impacted Mandibular Third Molars

Objective. To assess the incidence of dentigerous cystic changes in the follicles of radiographically normal impacted mandibular third molars. Methods. One hundred and thirteen follicles obtained after surgical removal of impacted mandibular third molars with radiolucency of less than 2.5 mm in the radiograph were sent for histopathologic evaluation to evaluate pathologic changes. Results. The incidence of dentigerous cystic changes observed was 15.9%, that is, 18 out of 113 patients (51 males and 62 females), with the maximum incidence of cystic changes seen in the follicular space size of 0.5 mm. The mean age of the patients included was 27.8 ± 8.1. The most common indication for extraction among the patients in this study was recurrent pericoronitis (95%). There were no statistically significant differences in occurrence of cystic changes based on age, gender, angulation, relation to ramus, depth, side of impaction, and follicle size (P>0.05). Conclusion. Dental follicles obtained from surgically removed impacted mandibular third molars should be submitted for histopathologic examination irrespective of the radiographic size of the follicle

A cross sectional study of ossicular chain disruption in COM patients and associated pre-operative predictors in a tertiary care center

Aim: Both types of COM, mucosal as well as squamous may lead to erosion of the ossicles. Pre-operative assumption of ossicular necrosis enables the surgeon to plan surgical steps, duration for surgery and arrangement for specific equipments and materials required for ossiculoplasty. Our objective was to find out magnitude of ossicular chain discontinuity in COM patients and to find out its association with clinical presentation like duration of discharge and hearing loss, otoscopic examination, findings of X- Ray mastoid (lateral/oblique) and pure tone audiometry (PTA).Method:This is a descriptive type hospital based cross sectional study. 100 patients were included in the study. All the patients underwent preoperative otoscopy, PTA and X ray mastoid. All patients underwent needful otological surgery in form of tympanoplasty or mastoid surgery and findings including ossicular chain status and erosion of the individual ossicles were noted.Results: Ossicular chain was found to be disrupted in 43 cases. Our study showed positive correlation for retraction pathology (p=0.00), long standing history of ear discharge (p=0.269), sclerosed mastoid (p=0.00). Moderate type of conductive hearing loss was also associated significantly with ossicular necrosis (p= 0.00, 0.112). Incudo-stapedial joint exposure had no significant relation with ossicular erosion.Conclusion:We conclude that history, otoscopic findings, PTA and x-ray mastoid can be reliable pre-operative predictors of ossicular erosion.Ossicular chain erosion was more prevalent in patients having cholesteatoma, long duration of ear discharge &amp; hearing loss, retraction pockets as compare to perforation, postero-superior quadrant involvement, moderate CHL and sclerosed mastoid