Why Listening Doesnt Always Work Essays - Carbon Dioxide

Why Listening Doesn't Always Work The Night I Became a Convict (Well it sure seemed like it) Introduction: Police Sirens glaring ? lights flashing ? nervous and full of fright Thesis Statement: If all seems almost perfect and going so well, that is when carefulness and planning becomes most critical and imperative (Transition: It happened one night around two years ago.) I. Senior, high school doing excellent ? student body president and numerous awards- flying high in a small community A. Playing cards at friend's Mark house- got bored- suggested dry ice bombs B. Went get dry ice- made bombs in yard ? got on to bigger pranks C. Rode around- put into mailbox (exploded) ? then into other one (Transition: Little did we know.) II. Police pulled us over into driveway, Summoned us, people turned up in droves A. Parents' reaction, community's reaction B. Community service, apology to victims C. Rebuilding of mailboxes (Transition: Since then, everyone jokes and pokes fun at us) III. The regaining of our reputation, relief, humility A. Great humbling experience B. Taught us to think things over C. Not to be overcome with irrational thinking D. Hindsight is 20/20 Summary: Be thankful on your way to the top and don't forget the little things that got you there because one little mischievous action could ruin it. Your reputation is very fragile. Years to build-one action to tear it all down. Conclusion: And it was so that this event which now I can tell with a smile and in light-heartedness that had a very dramatic effect on my life and shaped it into what it is now. I now approach options with extreme caution and look at the possible consequences. Speech and Communcations

study on judges essays

study on judges essays 1. What are the major findings with regards to the impact of race in each area of study? Finding on this studies have been a major impact on Judges due to minority judges have been well looked at through the eyes of the world. Progress has been made in appointing minorities to the federal bench and nearly three out of four minorities are confirmed. 2. How has the policy of affirmative action helped in accomplishing the application of the goals of Justice and equality? Despite the progress that has been made in recent decades particularly with civil right laws and court decisions, most of the problems still persist. Supporters of initiative action who were opposed to an affirmative action wanted similar words to be used in the Civil Rights Act of 1964. Words to be included were discrimination, and preferential treatment. In the affirmative action there is a need of overt racism. Such remedies are still required to provide equal access for all. 3. What are the recommendations given by the ABA study group? To understand one another is required that we go through a generation of education. Even though we have overcome some of the shortfalls of the past dealing with racial justice we need to work ourselves to insure mutual respect be carried out among all citizens. 4. What are the conclusions drawn from this study? Today we can bring all our thoughts together in order to unite and to promote righteous Judgment, equal justice, and fairness. Most of our associations represent a powerful force to transform injustice into justice for all. ...

Every IB Geography Past Paper Available Free and Official

Every IB Geography Past Paper Available Free and Official SAT / ACT Prep Online Guides and Tips If you are preparing for your IB Geography SL/HL papers, studying your notes is likely not enough to get a 7. Taking practice tests using IB Geography SL/HL past papers is the only way to ensure you know what to expect the day of your exam. You'll be better prepared because you'll know the test length and format...and you'll be more confident because you're more familiar with the question formats! In this article, I'll let you know where to find IB Geography SL/HL past papers- both free and paid- to help you excel on your own IB Geography exam. Where to Find Free IB Geography Past Papers IBO has been getting stricter about allowing unauthorized official past papers to roam free online in the past few years, so many of the previous sources for free past papers are unavailable. Frustratingly, IBO has not moved to fill the void with any free official sample papers for Geography, as they have for other subjects. As soon as free official IB Geography papers are released, we'll be sure to update this article. In the meantime, while it's still possible to search for free IB Geography papers online, we don't recommend it because there's no guarantee that those papers are necessarily real past IB papers. I haven't found any unofficial IB Geography past papers that explicitly state they were created by people other than the IBO, but if you find one, I DO NOT recommend using it, as it most likely will be very different from the actual IB Geography test. Where to Find Paid IB Geography Past Papers To get secure IB Geography past papers, buy them from the IBO. Their store has six full IB Geography SL and IB Geography HL past papers and markschemes from 2015 to 2018 available for purchase. Unfortunately, since papers and markschemes are sold separately and individually, buying all the papers and markschemes for a single test will run you around $18 for HL and $12 for SL. Buying all six available exams is pretty pricey, so we advise sticking to the two most recent tests in the store- November 2017 and May 2018- because these papers will be most similar to the test you take. Two exams should provide plenty of practice for most students. (Currently, only SL/HL paper 1 and HL paper 3 are available for November 2018, so if you want extra paper 3 practice for HL or paper 1 practice for both SL and HL, you might also consider getting those.) How to Use These Past Papers A full practice IB Geography test will take you 2 hours and 45 minutes for SL or 4 hours and 30 minutes for HL. If you are going to spend that much time, you need to be getting realistic practice and learning from these tests. To ensure you do, follow these guidelines. #1: Take the Test Over 2 Days The actual IB exam schedule splits Paper 1 and Papers 2 and 3 over two days. SL and HL students take Paper 1 the first day. Both take Paper 2 the second day, and HL students also take Paper 3 the second day. You should mimic this schedule so that you have realistic practice. #2: Use Accurate Test Timing You need to get used to the pacing of the test. The time allowed per paper is: Geography SL Paper 1- 1 hour 30 minutes Paper 2- 1 hour 15 minutes Geography HL Paper 1- 2 hours 15 minutes Paper 2- 1 hour 15 minutes Paper 3- 1 hour Stick to this timing exactly. Don’t give yourself even an extra second. Otherwise, you won’t be prepared for the pacing of the real exam. Also, you will likely get an unrealistic, inflated practice test score if you give yourself extra time. Stick to the real timing, so you get a realistic practice test score. #3: Check Your Answers Once you finish your exam, review your mistakes. You need to review so that you figure out what you are doing wrong before you take the real IB Geography exam. If you do not review, you will not know what mistakes you are making and will make the same ones on the actual IB Geography exam. Take a bit of time (at minimum an hour) to review. You should be emphasizing the quality of your practice and not the quantity of practice. It is far better to take two practice tests with in-depth review than eight tests with no review. What’s Next? Learn more about IB Geography: IB Geography Study Guide Check out where to find past papers for your other classes: Every IB Biology Past Paper Available: Free and Official Every IB Business and Management Past Paper Available: FREE and Official Where to Find IB Chemistry Past Papers - Free and Official Every IB Economics Past Paper Available: Free and Official Every IB English Past Paper Available: Free and Official Every IB History Past Paper Available: Free and Official Every IB Math Past Paper Available: Free and Official Where to Find IB Physics Past Papers - Free and Official Want to improve your SAT score by 160 points or your ACT score by 4 points? We've written a guide for each test about the top 5 strategies you must be using to have a shot at improving your score. Download it for free now:

Physical science Essay Example | Topics and Well Written Essays - 750 words

Physical science - Essay Example Thirdly, fission and fusion reactions possess the capacity turn the energy associated with ordering of subatomic particles into nuclear energy (How is Energy Converted). Fossil fuels pertain to fuels formed out of the organic remains of prehistoric plants and animals that undergo natural process of anaerobic decomposition and these fuels are chiefly comprised in coal, gas, and oil. It normally takes nearly 700 million years for decaying plant and animal matters to be fossilized upon exposure to extreme levels of heat and pressure into usable fossil fuels which are mostly rich in carbon with coal, natural gas, and petroleum by composition. Being a non-renewable source of energy, fossil fuels may be volatile or non-volatile as materials ranging from those of minimal C to H ratios as methane gas and liquid petroleum to materials with heavier carbon content than hydrogen as in the case of anthracite coal. In modern times, fossil fuels are confronted with the perils of continuous depletio n at a rate that alarmingly exceeds that of their production which implies that renewable substitutes with equivalent advantages ought to be discovered and settled at for corrective resolution (Lecture 10: Fossil Fuels as Energy Sources). Aside from being a flexible non-renewable energy source, according to their structure, depositional environment, and thermal reactions, fossil fuels draw a potential attraction due to the fact that most of world’s reserves of oil and natural gas come from deformed rocks whereas a great quantity of coal may be derived from sedimentary rock layers that do not undergo deformation. Sediments are readily found everywhere on which are comprised marine organic matter filled with oil and gas in high proportions to make opulent fossil fuel amounts. Because of low oxygen concentration on environments in which massive deposits are preserved and coal forms that gather toward bogs and swamps, fossil fuels can be acquired with much convenience. Under natu ral circumstances, fossil fuels are made beyond human intervention since thermal processes may occur spontaneously after decomposing organics goes through preservation to become fossil fuels at a later time. Aside from fossil fuels, renewable alternatives could be wind energy and geothermal energy or heat derived from the earth by means of a natural geologic process. As a form of solar energy, the energy of the wind is found to comprise turbulent masses of air rushing to even out the differences in atmospheric pressure formed when the sun heats the air more in one place than in another. For centuries, wind power has been utilized extensively in pumping water, grinding grain, and producing electricity of the modern age. Wind turbines as major replacements to windmills perform the course of wind power upon conversion of the wind’s kinetic energy to mechanical energy which sustains small to large farms and villages with clean and renewable loads of electricity (Freris, 1990). Mo dern technological advancements in the fields of engineering and science have revolutionized the old design in windmills with a flexible range of

Clinical Epidemiology and Decision Making Case Study Essay

Clinical Epidemiology and Decision Making Case Study - Essay Example These spores thus need water or moisture to germinate and flood provides them the ideal environment to grow. Molds if inhaled can cause allergic reactions that affect the respiratory tract. Other illnesses include sinus congestion, sore throat and breathing problems. The health risks can be more for children and elderly people as well as people with low immune systems. Mold can also have severe implications on structural strength of buildings as well which may compound the problem in flood stricken areas. The field of clinical epidemiology suggests that general practitioners must consider facts based on population based studies of diseases and base their treatment and design preventive measures on these measures. Clinicians may use these statistics towards better patient care. In this paper we attempt to explore how clinical epidemiology may be beneficial to guide and deal with detection, prevention and treatment of mold in flood hit areas. It is pertinent to note that mold may appea r soon after the flood and may carry on until there is moisture. For this reason it is important that the rehabilitation process may not be started unless all moisture dries out. For the purpose, the health practitioners treating the disease need to be advised before and immediately after the floods about the types of molds in the area as well as the extent of illness in the area. Also, the health practitioners need to know about the medical facilities that they would have as well as chalk out a method to deal in case that it takes the form of an epidemic. These practitioners need to be told that they must not look to test every individual due to resources constraints and would be better served to look for symptoms. 2. Types of Molds Evidence from clinical epidemiology suggests that there are three types of molds that can affect people in the aftermath of a flood. These are mentioned below: i. Allergenic These types of molds are the least damaging as they affect only those individua ls that are already weakened by illness or disease and a have a weakened immune system. Although these molds are present all year, they thrive in areas where the moisture content is significantly high. This essentially means that these types of molds can exist in the aftermath of a flood. These molds result in sneezing and cause allergic reactions. Thus they do not have life threatening affects unlike other types of molds that might result in severe respiratory problems including congestion of the windpipe and choking. Mold spores are examples of allergenic molds. ii. Pathogenic This type of mold may cause respiratory tract infections. For persons with a weakened immune system, this may result in severe illness and may be possibly life threatening. However, healthy individuals may develop hypersensitivity but do not incur infection. This is why it is imperative that children and elders are guarded against this type of a mold infection. The bipolaris mold is one example of a pathogen ic mold. The mold may manifest itself as mycotic keratitis and sinusitis etc. This type of a mold can affect both immune-competent as well as immune-compromised individuals with different repercussions. iii. Toxigenic The most devastating strain of mold produces myotoxin which can cause some seriously undesirable health problems. This is an extremely toxic strain of mold which may not only

Statistical techniques for cryptanalysis

Statistical techniques for cryptanalysis Introduction: Cryptography is the art of writing messages in code or cipher, to disguise, and thereby secure the content of a particular stream of text. When encrypted, a plain text message can be revealed only through the use of the key used to encode the cipher. Cryptography does not mask the existence of the message, but does disguise its content [1]. In contrary, cryptanalysis is the art of recovering the plaintext of a message without access to the key. Successful cryptanalysis may recover the plaintext or the key for a specific ciphertext [2]. There are five general types of cryptanalytic attacks:- 1. Ciphertext-only attack: In this type of attack, the cryptanalyst has a series of cipher texts encrypted using the same encryption algorithm. Then, the cryptanalyst deduces the plain text of each of the cipher texts or identifies the key used to encrypt the cipher text 2. Known-plaintext attack: In this type of attack, the cryptanalyst has a series of ciphertext and their corresponding plaintext values encrypted using a specific key. The cryptanalyst then tries to deduce the key by forming a relationship between the ciphertext and plaintext entries. 3. Chosen-plaintext attack: In this type of attack, the cryptanalyst not only has access to the ciphertext and associated plaintext for several messages, but he also chooses the plaintext that gets encrypted. His job is to deduce the key used to encrypt the messages or an algorithm to decrypt any new messages encrypted with the same key. 4. Frequency analysis: It is the study of thefrequency of lettersor groups of letters in aciphertext. The method is used as an aid to breakingclassical ciphers. Frequency analysis is based on the fact that, in any given stretch of written language, certain letters and combinations of letters occur with varying frequencies. 5. Rubber-hose cryptanalysis: The cryptanalyst threatens, tortures or blackmails the person who has the key until they give it up. Among the many cryptanalytic techniques, frequency analysis or frequency counting is the most basic technique applied to break substitution cipher based algorithms, among the varied list of attack techniques. The basic use of frequency analysis is to first count the frequency of ciphertext letters and then associate guessed plaintext letters with them. More complex use of statistics can be conceived, such as considering counts of pairs of letters digrams, trigrams, and so on. This is done to provide more information to the cryptanalyst. It exploits the weakness in the substitution cipher algorithm to encrypt similar plaintext letters to similar ciphertext letters. Frequency analysis based cryptanalysis techniques were used to break ciphers based on the traditional cryptographic algorithms, but they do not work well with the modern block cipher based cryptographic algorithms. Statistical properties of English: Frequency analysis based cryptanalysis uses the fact that natural language is not random in nature and single alphabetic based substitution does not hide the statistical properties of the natural language. In the case of encryption using monoalphabetic substitution, to start deciphering the encryption it is useful to get a frequency count of all the letters. The most frequent letter may represent the most common letter in English, E followed by T, A, O and I whereas the least frequent are Q, Z and X [7]. Statistical patterns in a language can be detected by tracing the redundancy of the text in the language. It has been realized that various universal regularities characterize text from different domains and languages. The best-known is Zipfs law on the distribution of word frequencies [5], according to which the frequency of terms in a collection decreases inversely to the rank of the terms. Zipfs law has been found to apply to collections of written documents in virtually all langu ages [5]. English language characters have a very high redundancy rate when used for cryptographic substitutions. If we have a message encrypted using the substitution cipher that needs to be cracked, we can use frequency analysis. In other words, if the sender has used an encryption scheme, that replaces one letter in the English to be another letter in English, we can still recognize the original plain text as, the frequency characteristics of the original plain text will be passed on the new cipher text characters [4]. To apply frequency analysis, we will need to know the frequency of every letter in the English alphabet, or the frequency characteristics of the language used by the sender to encrypt the text. Below is a list of average frequencies for letters in the English language. So, for example, the letter E accounts for 12.7% of all letters in English, whereas Z accounts for 0.1 %. All the frequencies are tabulated and plotted below:- For example, let us consider the following sentence: We study Cryptography as part of our course. Using a simple substitution cipher, let us consider the following: a->c , b-> d, c->e..w->y, x->z, y->a, z->b So, the cipher text becomes: yg uvwfa etarvqitcrja cu rctv qh qwt eqwtug. A simple frequency analysis of the cipher text can be carried out and the results are as given below: The above data can be used by a cryptanalyst to identify the key or the plaintext by using simple substitution to the cipher text till a suitable plaintext value is not identified. Apart from the use of mono alphabetic frequency analysis, cryptanalysts also identify frequency of paired letters better known as digram frequency and that of three letter words, called as Trigram frequencies. These help the cryptanalyst to exploit the redundant features of English language to break the cipher. The most common Digrams (in order): th, he, in, en, nt, re, er, an, ti, es, on, at, se, nd, or, ar, al, te, co, de, to, ra, et, ed, it, sa, em, ro. The most common Trigrams (in order): the, and, tha, ent, ing, ion, tio, for, nde, has, nce, edt, tis, oft, sth, men Table 1: Digram and Trigram Frequencies [6] These help in identifying the most commonly used terms in English to break a cipher. The digram frequencies are used to break two letter words such as an, to, of etc and the trigram frequencies are used to break three letter words such as the, are, for etc. After breaking a significant two letter and three letter words, it is practically east to identify the key from the cracked values of plaintext by matching the corresponding values in the ciphertext. This huge weakness in English language is used to break cipher texts encrypted using simple algorithms that make use of English alphabets. In practice the use of frequency analysis consists of first counting the frequency of ciphertext letters and then assigning guessed plaintext letters to them. Many letters will occur with roughly the same frequency, so a cipher with Xs may indeed map X onto R, but could also map X onto G or M. But some letters in every language using letters will occur more frequently; if there are more Xs in the c iphertext than anything else, its a good guess for English plaintext that X is a substitution for E. But T and A are also very common in English text, so X might be either of them also [4]. Thus the cryptanalyst may need to try several combinations of mappings between ciphertext and plaintext letters. Once the common single letter frequencies have been resolved, then paired patterns and other patterns are solved. Finally, when sufficient characters have been cracked, then the rest of the text can be cracked using simple substitution. Frequency analysis is extremely effective against the simpler substitution ciphers and will break astonishingly short cipher texts with ease. Attacks on Traditional algorithms Encrypting using traditional algorithms have been defenseless against cryptanalytic attacks as they use bit by bit encryption, which can be easily broken using frequency analysis based attacks. 1. Caesar Cipher: Considering the case of one of the oldest ciphers, the Caesar Cipher, this cipher replaces one letter of the plaintext with another to produce the ciphertext, and any particular letter in the plaintext will always, turn into the same letter in the cipher for all instance of the plaintext character. For instance, all Bs will turn into Fs. Frequency analysis is based on the fact that certain letters, and combinations of letters, appear with characteristic frequency in essentially all texts in a particular language [9]. For instance, in the English language, E is very common, while X is not. Likewise, ST, NG, TH, and QU are common combinations, while XT, NZ, and QJ are very uncommon, or even impossible to occur in English. This clearly shows how the Caesar cipher can be broken with ease by just identifying the frequency of each letter in the cipher text. A message encrypted using Caesar cipher is extremely insecure as an exhaustive cryptanalysis on the keys easily breaks the code. 2. Substitution Ciphers: The Caesar cipher forms a subset of the entire set of substitution ciphers. Here, the key of the encryption process is the permutation of all the twenty six characters of the English alphabets. Rather than choosing a particular key for all encryption process, we use a different key for successive encryption processes. This technique increases the number of possible key to 26!, which is about 4 X 1026, which eliminates the exhaustive cryptanalysis attack on the keyspace [7]. To decrypt the cipher the, statistical frequency distribution of single letter occurrence in English language is analyzed. Then, the digram and trigram frequencies of standard English words are compared with the frequencies of the trigrams in the cipher to finally reconstruct the key and in turn decipher the text. This is an efficient method to break the substitution cipher as, each plaintext letter is represented by the same ciphertext letter in the message. So, all properties of plaintext are carried on to the cipher text. 3. Vigenere Cipher: In a Vigenere cipher, there is greater security as, a given plaintext letter is not always represented by the same ciphertext letter. This is achieved by using a sequence of n different substitution ciphers to encrypt a message. This technique increases the possible number of keys from 26! to (26!)n. Although this was considered to be unbreakable, the Kasiskis method of attacking a Vigenere cipher yielded successful results of decrypting the message. According to this method, the first step is to find the key length (n). Find identical segments of plain text that get encrypted to the same ciphertext, when they are b positions apart, where b=0 mod n. According to Kasiski, the next step is to find all the identical segments of length greater than 3, and record the distance between them [7]. This can then be used to predict the length of the key (n). Once this is found the key is found by an exhaustive search of the keyspace for all possible combinations to identify the key. This is done by substituting all possible values for n to generate substrings. Once the substring is formed, the plaintext message can be automatically identified by using the back substitution of the key into the cipher [7]. This can be done for all possible values for n until finally arriving at the actual key, which reveals the plaintext that was encrypted. This method can take a long time to break the key to identify the plaintext incase the key length is very long, as the keyspace value would be large for larger keys. Defeating frequency based attacks: Frequency based attacks have been used for a long time to break traditional encryption algorithms. It uses the fact that, traditional encryption algorithms do not eliminate the statistical properties of the language upon encryption. The first way to defeat frequency based attacks is to encrypt blocks of characters at a time rather than single letters [7]. This would ensure that, the same text in the plaintext is not encrypted to the same text in the ciphertext upon encryption. For e.g., if we use the Caesar cipher encryption scheme, the word ADDITIONAL will be encrypted to CFFKVKQPCN, we can see that the alphabets A, D and I are repeated more than once and at each instance, the encryption scheme used always encrypts A to C, D to F and I to K. This can clearly be used during frequency analysis to analyze the redundancy of the characters and in turn map them back to get the original plaintext character. Using a block encryption scheme, one can be satisfied that, this phenomenon does not occur as, in a block encryption scheme, the whole plaintext is broken into chunks or blocks of data, that is fed in as input to the encryption algorithm. The algorithm then, reads the input block along with the key and encrypts th e complete block of plaintext, rather than individual characters, so there is a smaller chance that two blocks will produce the same chunk of ciphertext. The second way of defeating frequency analysis is to make use of synonyms of words [7], rather than repeating the same word over and over again in a sentence. There are a lot of words in English, which have more than one synonym, thus providing with a set of words to be used as convenient in the particular context. To help in the selection of a synonym, grammar checking would have to be used to ensure that, the meaning expressed in the sentence is not altered by changing the words. Attacks against this technique could include creating a list of the best synonyms, but this would not help the attacker as different word could be used at each instance the same meaning needs to be expressed, defeating the benefit of this technique. This technique of using alternate words to represent common words to defeat cryptanalysis attacks is called Homophones [7] in cryptography. A third technique that can effectively defeat cryptanalysis is Polyalphabetic substitution, that is, the use of several alphabets to encrypt the message [3], rather than using the same substitution technique again and again. The Vigenere Cipher is a form of Polyalphabetic cipher. This ensures that, no two characters are encrypted to the same ciphertext alphabet in the same message. This ensures that, direct frequency analysis of the cipher is not possible to successfully retrieve the original message. However, other techniques need to be used to identify the key length, if this is possible, then frequency analysis attack could be used to identify the original plaintext message successfully. Finally, a possible technique that could be used to defeat frequency analysis is to encrypt a single character of plaintext with two ciphertext characters [3]. Upon encountering the same character twice, then different characters should be used to encrypt the message. This can be achieved by using a key size double that of the plaintext message and then encrypting the same plaintext with two values in the key and save them together for the same plaintext character. This would ensure that no two plaintext characters will have the same ciphertext character, defeating the frequency analysis method of breaking the cipher. Modern encryption algorithms and cryptanalysis: Modern cryptographic algorithms take a better approach in defeating frequency analysis based attacks. The cryptographic algorithms nowadays use block encryption, rather than encrypting characters bit by bit, thus eliminating the redundancy of ciphertext alphabets for similar plaintext alphabets. Block ciphers are the central tool in the design of protocols for shared-key cryptography. A block cipher is a function E: {0, 1}k ÃÆ'- {0, 1}n à ¢Ãƒ ¢Ã¢â€š ¬Ã‚   {0, 1}n. This notation means that E takes two inputs, one being a k-bit string and the other an n-bit string, and returns an n-bit string [2]. The first input is the key, which is used to encrypt the secret message. The second string is called the plaintext, and the output is called a ciphertext. The key-length k and the block-length n are parameters associated to a specific block cipher. They vary from block cipher to block cipher, and depend on the design of the algorithm itself. Some of the most trusted symmetric ciphers inclu de AES, Triple-DES, Blowfish, CAST and IDEA. In public-key cryptography, the most commonly used cryptosystems are RSA and the Diffie-Hellman systems, which have not been found to have any vulnerabilities till date. Preferably, the block cipher E is a public specified algorithm. In typical usage, a random key K is chosen and kept secret between a pair of users. The function EK is used by the sender to encrypt the message, for a given key, before sending it to the intended receiver, who decrypts the message using the same key [2]. Security relies on the secrecy of the key. So, at first, one might think of the cryptanalysts goal as recovering the key K given some ciphertext, intercepted during transmission. The block cipher should be designed to make this task computationally difficult. In order to achieve this, the algorithms that are used to encrypt the message must be designed with a high degree of mathematical complexity, which cannot be reversed to obtain the plaintext from a known ciphertext. The length of the key used during encryption of a message plays an important role in deciding the effectiveness of an algorithm. Key length is conventionally measured in bits, and most of the well known strong ciphers have key lengths between 128 and 256 bits. A cipher is considered strong if, after years of attempts to find a weakness in the algorithm, there is no known effective cryptanalytic attack against it. This indicates that, the most efficient way of breaking an encrypted message without knowing the key used to encrypt it is to brute force it, i.e. trying all possible keys. The effort required to break an encrypted message is determined by the number of possible keys, known as thekeyspace. Knowing the speed of the computer to break the key, it is easy to calculate how long it would take to search the keyspace to break a particular cipher [2]. For example, considering a cipher that uses 128-bit keys, each bit can either be 0 or 1, so, there are 2128 or 3ÃÆ'-1038 keys approximately. Suppose we imagine that about ten billion computers are assigned the task of breaking the code, each capable of testing ten billion keys per second, then, the task of running through the entire keyspace would take around 3ÃÆ'-1018seconds, which is about 100 billion years. But, in fact, it would be necessary to run through only half the keyspace to hit upon the correct key, which would take around 50 billion years. This is longer than the estimated age of the universe according to modern cosmology, which is about 15 billion years [2]. This shows that, it is practically infeasible to crack modern cryptographic algorithms using Brute Force attacks. So, one can imagine the effectiveness of the modern cryptographic algorithms and their resistance towards cryptanalytic attacks. Conclusions: Cryptography has progressed in recent years and modern cryptographic algorithms have proved to be successful in defending against most forms of cryptanalytic attacks. Frequency analysis based attacks have proved to exploit the weaknesses in traditional encryption algorithms into revealing the plaintext message that was encrypted using them. The natural language used to encrypt messages is not considered to be random in nature, which is exploited by frequency counting based attacks. Based upon the frequency of letters that occur in the ciphertext, one can guess the plaintext characters due to their redundancy rate and the specific combination of letters in a word. This weakness can be repelled by using stream ciphers, which do not carry the redundancy in the plaintext to the ciphertext. Modern block cipher, encrypt a chunk of plaintext into ciphertext and vice versa, eliminating the redundancy of language used in encryption. Although the algorithm plays an important part, it is the key length used in block ciphers that helps in repelling cryptanalysis. Modern ciphers use a key length starting from 128 bits, eliminating the possibility of a brute force attack to decrypt the message. The higher the key length, the more time it takes to break these ciphers. These advantages have made modern cryptographic algorithms more popular among the security community. No known weaknesses have been found in these algorithms yet, that may allow one to identify the plaintext message. Bibliography: [1] Stallings, W., Cryptography and Network Security, Chapter 1, Third Edition, Prentice Hall, 2003 [2] Schneier, B., Applied Cryptography, Chapter 1, Second Edition, John Wiley Sons, New York City, New York, USA, 1996 [3] Hart, G.W., To Decode Short Cryptograms, Communications of the ACM 37(9), 1994, pp. 102-108 [4] Lee, K.W., Teh, C.E., Tan, Y.L., Decrypting English Text Using Enhanced Frequency Analysis, National Seminar on Science, Technology and Social Sciences (STSS 2006), Kuantan, Pahang, Malaysia [5] Zipf, GK., Human Behaviour and the Principle of Least Effort, 1949, Cambridge: Addison Wesley Publications. [6] Lewand, R.E., Cryptological Mathematics, The Mathematical Association of America, 2000, Pages 345-346 [7] Stamp, M and Low, R.M., Applied Cryptanalysis, 2007, Chapter 1 and 2, John Wiley Sons, New York City, New York, USA [8] http://www.simonsingh.net, Online internet frequency analysis tools [9] http://www.textalyser.net, online text analysis and frequency analysis information

Five of Frankenstein Essay

This line suggests that the creature was fairly friendly, rather than demonical: ‘†¦ while a grin wrinkled his cheeks’. The creature was very similar to a new born baby, with no experience in life and no knowledge of how to communicate and act: ‘His jaws opened, and he muttered some inarticulate sounds’. Despite the creature’s lack of knowledge and experience, Victor somehow manages to treat the creature in an appalling manner. These set of events portray Victor as somebody who is very cruel and selfish, furthermore, it makes the reader sympathise for the creature. The idea of bringing someone into the world by stitching together pieces of dead bodies and passing electricity through the corpse raises the question of immoralities; moreover the way Victor brought life into the world and then abandoned it is a terrible lot worse. In this story, Victor Frankenstein acted similarly to the Ancient Greek character ‘Prometheus’, as he played God. He felt that he had the right to create new life. He then realised how wrong it was, however by that time it was too late. In the 19th century, most people in England were very religious, so the way Victor plays God in the story would have been widely frowned upon. It was extremely uncommon for people to see boundaries and morals being questioned and stretched in this way. The creature that Victor created was far from a monster, it was but a helpless, needy being that he had abandoned, and it was not very different from abandoning a new born baby. Society cruelly rejected him due to his appearance, which goes to show how narrow minded society can be. This could have been part of the message that Mary Shelley wished to send out. The true monstrous figure in the story is Victor. This is all down to his cruel nature and the disgust he shows towards the creature he spent two years trying to bring to life. Victor even goes as far as describing the creature as a ‘half-distinguished light’, meaning he felt the creature was merely ‘half of a human being’. The author, Mary Shelley, in my opinion was trying to send out the messages: it is wrong to play God and that society can sometimes be very judgemental. The reasons are that Mary Shelley depicts the creature as helpless, confused and needy, so that the reader will sympathize towards him, whereas she depicts Victor as a cruel and selfish person, which supports the point of playing God being wrong. The reason I believe Mary Shelley tried to send out the message of society often being judgemental is so that people will realise that appearances are not everything, and that they can learn to avoid judging people by this before getting to know their past and present situation. 1,060 words Aran Atwal Show preview only The above preview is unformatted text This student written piece of work is one of many that can be found in our GCSE Mary Shelley section. Download this essay Print Save Here’s what a teacher thought of this essay 4 star(s).