Timed Efficient Stream Loss-Tolerant Authentication (TESLA)

Timed Efficient Stream Loss-Tolerant Authentication (TESLA) When considered as a security solution for ADS-B, asymmetric-key encryption has two major drawbacks. The first issue is that current asymmetric-key schemes have no compact encryption implementations, and would result in an increase of the transmitted ADS-B message length. The second problem is that unique encrypted ADS-B messages would be required for each recipient. To maintain a fully-connected network of n nodes would necessitate (n2 à ¢Ã‹â€ Ã¢â‚¬â„¢ n) unique broadcasts rather than n in the current system [15], which obviously does not scale well as the size of the network increases. As a possible answer to these two drawbacks, Costin et al. [3] have suggested what they term a lightweight PKI solution. In the lightweight PKI approach, node A transmits its digital signature over n messages, so that after every n messages, the surrounding nodes have received As digital signature. The recipients keep the messages until the entire digital signature has been transmitted and they can authenticate the buffered messages. The authors suggest that the PKI key distribution necessary for this scheme could be done during an aircrafts scheduled maintenance cycle [13]. A security scheme called Timed Efficient Stream Loss-Tolerant Authentication (TESLA) is a variation on traditional asymmetric cryptography that has been proposed for use on broadcast networks [19], [20]. With TESLA, senders retroactively publish their keys which are then used by receivers to authenticate the broadcast messages. A broadcasting node produces an encrypted message authentication code (MAC) which is included with every message. After a designated time interval or number of messages, the key to decrypt the senders MAC is published. Listening receivers who have buffered the senders previous messages can then decrypt the messages that were broadcast. When applied to ADS-B, this technique imposes a time delay on the broadcast due to the need to buffer messages, but it provides integrity and continuity of messages sent over the network. TESLA is an adaption of the TESLA protocol designed for use on wireless sensor networks. The TESLA protocol requires nodes in the network to be loosely time synchronized, with each node having an upper bound on the maximum clock synchronization error. As discussed earlier, asymmetric encryption schemes have high computation and communication overhead, which limit their usefulness as security approaches on the bandwidth-constrained ADS-B network. The TESLA protocol overcomes this problem by employing asymmetric-key encryption through a delayed disclosure of symmetric keys, which results in an efficient broadcast authentication scheme. When one considers the bandwidth and interference limitations on the ADS-B frequency channel, the TESLA design adaptations identify this protocol as a viable scheme for providing security in ADS-B. However, there are two obstacles to applying TESLA to ADS-B. The primary issue is that, while sufficiently good time synchronization could be provided via GPS, it would require modification to the protocol to accommodate the GPS timestamp field. The second problem is that in order for TESLA to be used for verifying the identity of a network node, it needs to be reinitialized which leaves it susceptible to memory- based DoS attacks. In spite of these drawbacks, TESLA is a promising security scheme for integrating into ADS-B. B. Aircraft Address Message Authentication Code The cryptographic solutions PKI and TESLA both have shortcomings in that they require modifications to the current ADS-B protocol. The Aircraft Address Message Authentication Code (AA-MAC) security solution utilizes a standard hash algorithm such as MD5 or SHA and a secret authentication key to perform message integrity [21]. The AA-MAC message source integrity scheme would require a slight modification to the existing protocol in that it would replace the current Aircraft Address (AA) field with the MAC, but the ADS-B message is otherwise unchanged. The AA-MAC approach proposes a different aircraft identification strategy, assigning a unique identifier to each aircraft that is good for the duration of a particular flight. As with PKI cryptographic approaches, the distribution of the secret key presents challenges for AA-MAC. Since MAC requires just one key which is used to uniquely identify a sender on the network, the simplest approach would be to distribute the secret key only whe n an aircraft intends to enter the air traffic control system and ADS-B network. The purpose here is to demonstrate a compatible security scheme that will mitigate threats posed by message injection and modification attacks, which are among the most critical vulnerabilities in the current ADS-B implementation. While AA-MAC does not provide data integrity, it is highly compatible with the existing 1090ES protocol and can be implemented at low cost relative to other security proposals, offering a feasible partial security solution for ADS-B. 4.1.2. Non-Cryptographic Schemes As we have seen, cryptographic security schemes are difficult to implement in a way that are not compatible with the existing infrastructure, primarily due to the problem of key distribution and management. Non-cryptographic approaches to network security avoid the challenge of key management and instead involve either some form of fingerprinting on the physical layer, or a frequency modulation scheme such as spread spectrum. A. Fingerprinting Schemes such as fingerprinting encompass various methods for authentication and identification, either based on hardware or software imperfections or characteristics of the frequency channel which are hard to replicate. Identifying signatures for legitimate nodes on the network provides data useful for the implementation of systems to detect network intrusions [22]. Software-Based Fingerprinting schemes attempt to isolate distinct characteristics of the software operating on network equipment. The development teams for different network equipment manufacturers often take widely varied paths when implementing software on a given device. These differences can be cataloged and later exploited to tell apart dissimilar network devices, and can be used to verify their continuity up to a certain degree. Hardware-Based Fingerprinting approaches seek to identify and catalog unique network hardware differences. Some of these differences can be used for radiometric fingerprinting, which takes advantage of differences in the modulation of a radio signal to catalog unique device signatures. Clock skew is another identifiable hardware feature that can be used to establish uniqueness between wireless devices. Since no two clocks are perfectly synchronized, time difference can be used to create signatures and enable identification. A third category of fingerprinting is Channel/Location-Based Fingerprinting. This fingerprinting method tries to exploit natural characteristics of the communications channel. Various approaches utilizing received signal strength (RSS), channel impulse response (CIR) and the carrier phase have shown that this can be a viable alternative to more traditional authentication and verification measures.

Parking slot system Essay

INTRODUCTION A parking space is a location that is designated for parking, either paved or unpaved. Parking spaces can be in a parking garage, in a parking lot or on a city street. It is usually designated by a white-paint-on-tar rectangle indicated by three lines at the top, left and right of the designated area. The automobile fits inside the space, either by parallel parking, perpendicular parking or angled parking. (http://en.wikipedia.org/wiki/Parking_space) In most countries where cars are the dominant mode of transportation, parking lots are a feature of every city and suburban area. Shopping malls, sports stadiums, mega churches and similar venues often feature car parks of immense area. Wikipedia(2007) There are lots of parking space here in the Philippines who are traditionally operated by the security guards. We don’t have a choice but to follow that traditional operation. Every day that we are traveling in the mall or in any place, we need to find a parking slot. Sometimes there is traffic inside the parking area because most of the drivers can’t find a parking slot for their vehicles. The traditional process of any parking areas are like a cycle, you will enter on the entrance and didn’t know if there is a space for you to able to park your car and you will be driving cyclical on the parking lot and suddenly you will be irritated because you can’t find any space for your car, and you have no choice but to head the exit. This is the cycle that every people experienced every minute, every hour or every day in every parking lot area. The problem of the parking areas is it can’t manage only by the security guard’s, they can’t search the whole area in every minute to know if there is a space for the new incoming drivers on the parking lot unless there is a security guard in every designated area. And most of the parking areas are too small for the customers who have private vehicles. The reasons why we are proposing this research is to reduce the problem of the vehicle drivers who are suffering to find an available space or slot in the parking areas. This research aim to help all the drivers to find a parking space faster and easier than the traditional system. STATEMENT OF THE PROBLEM How may the manual system be described in terms of: 1.1Time Time consuming of finding a space in parking lot. 1.2AccuracyandConsistency. Increase of problem in parking lot. 1.3Speed Slow in finding a slot for vehicles. 1.4Security No security guard will monitor your vehicles. How may the proposed system be described in terms of: 1.1Time Saving your time to find a parking space. 1.2AccuracyandConsistency Use automated car parking system to reduce wasting of time finding a parking slot. 1.3Speed It’s more quickly to find parking slot. 1.4Security The automated car parking system is more secured than the traditional system.

Seasonal Allergens

In Austin many people suffer from seasonal allergies which are triggered by mold spores and pollen grains mainly during spring and fall. Mold spores are responsible for causing seasonal allergic rhinitis also known as hay fever. Molds did not have a specific bloomy seasons but their presence in the air is affect by weather conditions such as rain, temperature, humidity and wind. There numbers increase during warm humid summer months and reach their peak during fall. O the other hand pollen grains have specific pollination period usually depending on the origin of the plant.When allergen substances and pollen grains enter the body, they cause the immune system to respond through an allergic reaction. During seasonal allergens people who are allergy sufferers should be encouraged to avoid the allergens by staying indoors. Allergy sufferers should learn to avoid early morning outdoor activities mainly because this is when pollen grains are being transferred from one tree to another. Pol len Allergy Pollens grains are protective sacks that certain male gametes that are necessary for plant fertilization.During pollination time, these male gametes are transferred to female plant for fertilization. Wind loving plants now rely on the wind to transfer their pollens grains. This is the main cause of allergic problems because the pollen grains of wind loving plant are very light in weight and air borne particles. In Austin, Texas trees like oak and elm pollinate during spring and therefore cause seasonal allergies in early spring. Ragweed plant is disastrous to allergy sufferers because it pollinates from mid August to October.The pollen grains of this plant are very light weight and can travel to a distance of 400 miles from the plant. Mold allergy Micro-scoping mold spores are present all year round floating in the air just like pollen grains, but they peak during summer and fall. Mold air borne allergies are both found indoors and outdoors and include cladosporium and a spergillus. The most common sign of these season allergens are sore throat, itchiness, running nose, sneezing and congestion. During seasonal allergic periods, pollen grain and mold spores are very high and they stick on clothing, hair, skin and pets.Pollen grain transfer usually takes place during the early morning period Cedar fever Cedar fever is also referred to as mountain cedar allergy which seasonally starts from December all the way to February. This allergy is caused by the mountain cedar tree and tree of the cypress family. The mountain cedar tree grows naturally to a maximum of 30 feet. It is an evergreen tree which the most allergenic tree in Austin Texas. The tree has both male and female plants and it pollinates from October to May. During this period, the male plant transfers its pollen grain to the female plant.This occurs mainly during the windy seasons when the branches of this tree are disturbed and its pollen grains appear like smoke in the air. Oak allergy Oak t rees shed allergen amount of pollen grains starting from February to late May. The sufferers of oak allergy usually reach the peak of their symptoms during mid April. Oak tree allergies can range from moderate to severe allergic reaction. Austin has a great diversity of oak tree are yellowish in colour will stick on house roofs, cars and outdoor furniture’s. Seasonal allergensAustin is rated among the top five worst places hit by allergies. It has three unique pollen seasons which occur during the Fall, the Spring and Winter. In the Fall, the ragweed plant and other weed are responsible for releasing their pollen grains usually from mid August all the way to early November. In Austin, this season last for a long period than in any other part of the country. During the Spring, the oak tree, Elm and Ash trees transfer their pollen grains starting from February to early June. In the winter, the mountain cedar tree releases its pollen from December up to February.Pollen counts fr om the central Texas are the highest pollen counts of any type of plant in the world. During days of high cedar pollen counts, people who are allergic to cedar cannot go outdoors without having serious allergenic symptoms. (Guyton, AC, and Hall, JE, 2006). Scientific review of human allergies Abstract Allergies are disorders of the immune systems that occur as a reaction to environmental substances. An allergic response also known as immediate hypersensitivity is characterized by excessive activation of mast cell by immunoglobulin E.Allergic responses can be divided into two pathophysiological phases including the acute response and the late-phase response. The acute or immediate response occurs immediately after being exposed to a particular allergen. Allergic responses consist of primary responses and secondary responses. A primary immune response occurs after a first encounter with an antigen. Human allergies have two major risk factors which include environmental and host factor s. Host factors include age, heredity and race while environmental factors vary from exposure to infectious diseases, dietary changes, allergen counts and environmental pollution.Allergic symptoms could be moderate or severe depending on the immune system of the affected person. Human allergies Scientific research studies suggest that allergies are the fifth leading chronic disease and affect more than 50 million people in the United States. There are various types of allergies ranging from allergic rhinitis to food allergy. Allergic rhinitis causes swelling of the nasal mucosa and respiratory discomfort such as running nose and sneezing. Skin allergies cause blisters and itchy rashes that rise from touching allergic substances.Allergy swelling can cause swallowing difficulties. Anaphylactic allergies cause severe symptoms such as bronchoconstiction, skin reaction and sometimes lead to death. Scientific studies show that children who have allergic parents have a higher likelihood of developing similar allergies. The human’s immune systems is developed in such a manner that it can detect a foreign organism in the body. If a foreign substance such as pollen is identified the body defence mechanism came into action to fight the foreign substance. The body produces immunoglobulin E to fight the detected foreign organism.(Leznoff. A. , (1999). Allergic symptoms usually occur when a sensitive person is exposed to a substance that could be harmless to other normal people. Allergic symptoms are mainly inherited but could also develop at any age depending on the time of exposure to allergens. There are three major categories of allergens including inhalants such as pollens, mold and dust. The other categories are ingestions and injected substances such as drug, beverages and vaccines. Allergies are disorders of the immune systems that occur as a reaction to environmental substances.An allergic response also known as immediate hypersensitivity is characterized by excessive activation of mast cell by immunoglobulin E. most allergic substances are airborne particles especially dust and pollen grains. Hay fever is an allergic reaction that occurs in response to airborne pollen and it causes sneezing, irritation of the nose and the redness of the eyes. Inhaled pollen grains could also cause asthmatic symptoms trough bronchoconstriction, shortness of breathe, wheezing and excessive production of mucus in the lungs.Allergic reactions can also result from food, medication and insect bites. Food allergies may cause symptoms such as vomiting, abdominal pains, swelling of the skin or diarrhea. Insect bites and medication cause a systematic response that is also known as anaphylaxis which affects multiple systems of the body. Human allergies have two major risk factors which include environmental and host factors. Host factors include age, heredity and race while environmental factors vary from exposure to infectious diseases, dietary changes, allerge n counts and environmental pollution. (http://www.setel. com/~allergy/Products/allergy) Seasonal allergy responses and how human health is affected Abstract Seasonal allergens have very adverse reactions on different people depending on the type of allergen and the immune system of each individual. Seasonal allergies could interfere with a person’s ability to perform their daily duties. In the United States, up to 35million people suffer from seasonal allergies and as a result, an average of 4 million workdays are lost each year. A majority of allergy sufferers have reported that they have difficulty sleeping or working effectively.Seasonal allergic responses During seasonal allergens people who are allergy sufferers should be encouraged to avoid the allergens by staying indoors. This method is effective when they limit outdoor activities especially when the pollen counts are at their peak. If one cannot afford going outdoors, they must take a shower and change clothes immedi ately after, because pollen grains stick to hair, clothing and skin. Allergy sufferers should learn to avoid early morning outdoor activities mainly because this is when pollen grains are being transferred from one tree to another.In cases where one must work outdoor, they should wear a dust and pollen mask that helps to prevent inhaling pollen grains, mold spores and dust. Allergy sufferers could respond to seasonal allergens through immunotherapy, whereby they get allergy vaccines which lead to reduction in allergic symptoms. After taking shots for a period of 3 to 5 years, allergy sufferers experience reduced symptoms and thus need less medication. Allergy shots are more effective for inhalants and insect bite allergies. other people can respond to allergens by taking medication to control the allergic symptoms.The common types of medication used include lung inhalers, nasal sprays and oral medication. Allergic symptoms could be moderate or severe depending on the immune system o f the affected person. Allergies are overreactions of the immune system to foreign substances such as pollen grains, peanuts, insect bites and certain medications. Allergic symptoms usually include sneezing, running nose, itching, skin rashes and wheezing. On many occasions allergic reactions could lead to asthma, which occurs when the airways are temporarily blocked or even narrowed due to exposure to certain allergens.Symptoms of an asthma attack mainly include difficulty breathing, wheezing, shortness of breathe or coughing. (http://allergies. about. com/od/alternatives/Alternative_Allergy_Treatment_Options. htm) Allergic responses Allergic responses can be divided into two pathophysiological phases including the acute response and the late-phase response. The acute or immediate response occurs immediately after being exposed to a particular allergen. Allergic responses consist of primary responses and secondary responses. A primary immune response occurs after a first encounter with an antigen.This type of response is small and has a long induction phase. On the other hand, secondary responses occur after a second exposure to a particular antigen. The acute allergic response occurs within minutes following an allergen exposure caused by the release of histamine and mast cell granules. This acute allergic response is referred to as type 1 allergic reaction. The type 1V allergic reaction may occur within a period of 6 hours to 12 hours after an exposure to an allergen. On detecting a foreign substance in the body, the immune system reacts to the antigen in two responses which include cellular response and antibody response.In cellular response, the immune system produces special white blood cells which are referred to as T lymphocytes, which have the capability of binding to the foreign antigens and destroying them. In the antibody response, the immune system reacts by producing and releasing blood proteins known as antibodies into the bloodstream. (Levinson , W. , (2004). When allergen substances and pollen grains enter the body, they cause the immune system to respond through an allergic reaction. The immune system produces antibodies which have mast cells attached to them.These antibodies bind to the allergen substances either on the skin, in the nose or in the respiratory system. On binding with allergens, mast cells become activated and release histamine, a substance that produces most of the symptoms associated with allergic reactions. The symptoms include wheezing, itching, sneezing and nasal congestions. Although these symptoms are meant to assist the body in fighting off the foreign substances, they could sometimes be very severe and fatal on some people. References Allergies, (2006a), Alternative Allergy Treatment Options, [Online], retrieved from Internet on 10 January 2007, http://allergies.about. com/od/alternatives/Alternative_Allergy_Treatment_Options. htm Allergy, (2006), What is Allergy, [Online], retrieved from Interne t on 10 January 2007, http://www. setel. com/~allergy/Products/allergy Guyton, AC, and Hall, JE, (2006), Textbook of Medical Physiology-11th Edition, Published by Elsevier, Pa. , ISBN 13-81-8147-920-3 Levinson, W. , (2004), Medical Microbiology & Immunology, 8th Edition, McGraw Hill Companies, ISBN 0-07-143199-3 Leznoff. A. , (1999), Provocative challenges in patients with multiple chemical sensitivity, J Allergy Clin Immunol 1997 Apr; 99 (4):438-42

Major General Romeyn B. Ayres in the Civil War