Учебно-методическое пособие Для студентов, аспирантов Таганрог 2008




НазваниеУчебно-методическое пособие Для студентов, аспирантов Таганрог 2008
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Grammar tasks


Test А. Choose the correct form of Passive Voice.

1. A sound IRM program founds/founded/is founded on a well thought out IRM policy infrastructure.

2. The underlined secure network services installed/was installed/were installed in accordance with the operational documentation.


Test B. Put the verbs in brackets in the correct form of Passive Voice.

1. Uncertainty (measure) inversely with the respect to confidence.

2. This work (finish) next month.

3. The papers of the conference (translate) into 12 languages.

4. Both expected frequency and exposure factor for fire (increase) by not having a fire suppression system.

5. The system (develop) in 1998.

6. Exposure factor (express) as a per cent.

7. Generally accepted Information Security Principles (base) on an Authoritative Foundation of supporting documents and guidelines.

8. It is essential that the process of analyzing and accessing risk (understand) by all sides.

Test C. Put the verbs in brackets in the correct form of Active or Passive Voice.

1. Back in the 90-s, Anti-virus researchers first (fight back) by creating special detection routines designed to catch each polymorphic virus, one by one.

  1. By hand, line by line, they (write) special programs.

  2. W.F.Friedman’s monograph «The index of Coincidence and its Application in Cryptography» (appear) in 1918.

  3. US Army and Navy (work) entirely in secret, when their specialists (begin) making fundamental advances in cryptography.

  4. H.Feistel, who earlier (worked) on identification friend or foe devices for the Air Force, (change) the sphere of his scientific interests.

Communication.

At the customs.

You’re going through the customs. Talk to the customs officer about your trip and luggage.


Writing.

DEPARTMENT OF THE TREASURE

UNITED STATES CUSTOMS SERVICE

CUSTOMS DECLARATION

PRESENT TO THE IMMIGRATION AND CUSTOMS INSPECTORS

EACH ARRIVING TRAVELLER OR HEAD OF A FAMILY MUST WRITE IN THE FOLLOWING INFORMATION. PLEASE PRINT.



1. Family Name Given Name Middle Initial


2. Date of Birth (Mo./Day/Yr)



3. Vessel or Airline & FLT. No


4. Citizen of (country)

5. Resident of (country)

6. Permanent Address


7. Address while in the United States


8. Name and relationship of accompanying family members.


9. Are you or anyone in your party carrying Yes

Any fruits, plants, meats, other plant or

animal products, birds, snails, or other live No

organisms of any kind?

10. Have you or anyone in your party been Yes

on a farm or ranch outside the USA in the

last 30 days? No

11. Are you or any family member carrying Yes

over $ 50000 (or equivalent value in any

currency) in monetary instruments such as

coin, currency, traveler’s checks, money No

orders or negotiable instruments in bearer

form?

12. I certify that I have declared all items

acquired abroad as required here in and that all

oral and written statements which I have made

there are true, correct and complete.

SIGNATURE

NON-CITIZENS ONLY 13. US VISA ISSUED AT (place)

14. Visa Date (Mo./ Day / Yr.)



Additional vocabulary.

  1. Adjustment - совмещение

  2. flexibility – гибкость (применения, оперативность

  3. standard-conforming protocol – протокол стандартного соответствия

  4. bulk data – массив данных

  5. be exploitable into an attack – использоваться для атаки

  6. withstand an attack – противостоять/выдержать атаку

  7. small-ability smartcard – платежная карточка с невысокой платежеспособностью?????????????????????????????????

  8. cipher block chaining - сцепление блоков шифртекста

  9. initialization vector – вектор инициализации

  10. parity bit – бит четности

  11. discard the bytes – исключить байты

  12. random padding – произвольное дополнение незначащей информацией или фиктивными битами, холостое заполнение

  13. elliptic curve cryptography - криптография на основе эллиптических кривых

  14. digital signature - электронно-цифровая подпись

  15. digital signature generation – производство электронно-цифровой подписи

  16. digital signature verification – проверка электронно-цифровой подписи

  17. factorization algorithm - алгоритм разложения на простые множители



Unit 4. Modern Methods of Cryptanalysis.


Vocabulary


What do the following forms and word combinations mean?

Incomprehensible ciphertext, automated aids, removing one bit of drudgery, overlapping superencipherment group, hill climbing algorithm, subkey, recover a DES key, encipher the known plaintext, flipped bit results, (original) trial key, trial encipherment, avalanche property of DES, ciphertext-only solution, mimic the process (of natural selection), chain of discrete elements


Texts

Pre-reading task.


What do you know about cryptanalysis? What cryptographic algorithms can you name?

Text 1. Cryptanalysis.

Cryptanalysis is hard work, requiring a willingness to endure many false starts, and a painstaking attention to detail. It requires intelligence to see subtle patterns in incomprehensible ciphertext.

Automated aids to cryptanalysis come in many forms. Some collected statistical information about ciphertexts, thus removing one bit of drudgery from human shoulders. Others, such as the Bombe used in attacking the German Enigma, or the DES cracker built by the Electronic Frontier Foundation, or the converted unit record equipment (punched card machines) which compared Japanese code messages to one another at various displacements to find messages with overlapping superencipherment groups, work by trying thousands, or millions, of possibilities, one after another.

Neither of these techniques is adequate to deal with many cipher systems, particularly modern ones. A well-designed cipher will not offer a simple opportunity to try different possibilities to find partial information about the key, and will have a key large enough to make trying every possible key hopeless. Nor is ordinary statistical information about the frequencies and contacts of bytes in the ciphertext likely to be much use.

Thus, approaches taken from the field of AI (artificial intelligence) have been tried. In these approaches, it is attempted to combine the speed of the computer with steps that at least slightly move towards the skill and judgement of a human cryptanalyst.

Hill-climbing

Because the individual bits of the subkeys in DES are actual bits taken from the 56-bit DES key, an approach like the following to recover a DES key must have occurred to many people.

Given a block of known plaintext, and its corresponding ciphertext, starting with a random 56-bit possible key, do the following:

  • Encipher the known plaintext with that key, and with every one of the 56 other keys obtained by inverting one bit of that key.

  • Compare the resulting ciphertext to the actual ciphertext.

  • In those of the 56 cases where the flipped bit results in the ciphertext produced differing in fewer bits from the actual ciphertext than that produced by the original trial key, invert that bit of the trial key to obtain the next trial key.

This is a simple example of a hill-climbing algorithm, where the number of bits by which a trial encipherment differs from the actual ciphertext are a measure of one's (lack of) altitude.

It would, however, never work against DES. That is because of the avalanche property of DES; changing a single bit in a DES key results in every bit of the block being enciphered being changed randomly after only a few rounds.

Thus, even attempting to improve the hill climbing algorithm above by, for each trial, enciphering the known plaintext for eight rounds with the trial key, and deciphering the actual ciphertext for eight rounds with the trial key, and then determining the number of bits by which these two results differed would not be enough to help.

Another idea would be to choose two rounds of DES, and by determining the input to those rounds by enciphering the known plaintext by the previous rounds, and the required output from those rounds by deciphering the actual ciphertext by the following rounds, examine the two 48-bit subkeys for the rounds, and, by examining the four possibilities for each group of 6 bits in those subkeys to produce the required change in each half of the block, find those which are consistent with the origin of those two subkeys from the original 56-bit key, and then try the resulting new 56-bit key or keys on the basis that it or they might be improvements over the preceding trial key.

Genetic Programming

A thesis by A. J. Bagnall described the ciphertext-only solution of some simple rotor machines by means of the technique of genetic programming.

Genetic programming is a method by which a computer produces an answer to a question, or even a computer program to perform a task, by mimicing the process of natural selection. As noted in the thesis, and in the book Artificial Life by Stephen Levy, this technique was originated by John Holland in the mid-1960s, and his student David Goldberg was one of the first to refine the technique so that it could be used in practice with real problems of importance.

It can be thought of as a special case of the hill-climbing algorithm, in that a quantitative measure of how "warm" the computer is in approaching the desired solution is required.

Programs or answers must be in the form of a chain of discrete elements, such that there is at least a reasonable likelihood that a chain formed by taking one chain, and replacing a span of elements within it by the corresponding elements from another chain, will "make sense". Random mutations are also usually used, although genetic crossover has been found to be much more important.

Starting with a random selection of solutions, those that work best are retained, and used as the parents of the next generation of solutions to be tried. Often, this retention is also randomized, so that better solutions have a higher probability of being retained.

One type of mutation that happens in real life has not, to my knowledge, been used for genetic programming yet. Occasionally, plants and animals will increase the size of their genetic inheritance by duplicating part of it. Thus, a finite state machine could mutate by becoming a machine with twice as many states. It might be useful to make provision for this where a problem might be more complex to solve than initially realized.

What automated aids to cryptanalysis do you remember? Characterize them in a few words.

What are the approaches to cryptanalysis?


Text 2. Cryptanalytic Methods for Modern Ciphers. Read the text and write its summary. Point out the facts that are new for you. Present them orally.

Block ciphers like DES are intended to be very hard to break, and they are largely successful in achieving this. Having even copious quantities of corresponding plaintext and ciphertext, it is intended that the fastest way to discover the key, so as to be able to decrypt other messages, would be a brute-force search, that is, trying every possible key until the right one is found.

Many block ciphers appear to meet this condition. Two cryptanalytic methods that can do slightly better with some of the earlier block ciphers, such as DES and LUCIFER, are differential cryptanalysis and linear cryptanalysis.

Other techniques, which are of interest against weaker ciphers, and which partially account for the fact that DES has sixteen rounds, instead of eight, such as hill-climbing techniques and genetic algorithms, are discussed in the next section.

In the book The Hut Six Story, Gordon Welchman first revealed one of the innovations used with the Bombe in connection with the cryptanalysis of the German Enigma. He also noted that it embodied a general principle which made present-day ciphers weaker than they might be expected to be.

Differential Cryptanalysis

However, if one is fortunate enough to have a large quantity of corresponding plaintext and ciphertext blocks for a particular unknown key, a technique called differential cryptanalysis, developed by Eli Biham and Adi Shamir, is available to obtain clues about some bits of the key, thereby shortening an exhaustive search.

After two rounds of DES, knowing both the input and output, it is trivial to determine the two subkeys used, since the outputs of both f-functions are known. For each S-box, there are four possible inputs to produce the known output. Since each subkey is 48 bits long, but the key is only 56 bits long, finding which of the four possibilities is true for each group of six bits in the subkeys is a bit like solving a crossword puzzle.

Once the number of rounds increases to four, the problem becomes much harder. However, it is still true that the output depends on the input and the key. For a limited number of rounds, it is inevitable, without the need for any flaws in the S-boxes, that there will be some cases where a bit or a combination of bits in the output will have some correlation with a simple combination of some input bits and some key bits. Ideally, that correlation should be absolute with respect to the key bits, since there is only one key to solve for, but it can be probabilistic with respect to the input and output bits, since there need to be many pairs to test.

As the number of rounds increases, though, the simple correlations disappear. Differential cryptanalysis represents an approach to finding more subtle correlations.

Instead of saying "if this bit is 1 in the input, then that bit will be 0 (or 1) in the output", we say "changing this bit in the input changes (or does not change) that bit in the output".

In fact, however, a complete pattern of which bits change and do not change in the input and in the output is the subject of differential cryptanalysis. The basic principle of differential cryptanalysis, in its classic form, is this: the cipher being attacked has a characteristic if there exists a constant X such that given many pairs of plaintexts A, B, such that B = A xor X, if a certain statement is true about the key, E(B,k) = E(A,k) xor Y for some constant Y will be true with a probability somewhat above that given by random chance.

Linear Cryptanalysis

Linear cryptanalysis, invented by Mitsuru Matsui, is a different, but related technique. Instead of looking for isolated points at which a block cipher behaves like something simpler, it involves trying to create a simpler approximation to the block cipher as a whole.

For a great many plaintext-ciphertext pairs, the key that would produce that pair from the simplified cipher is found, and key bits which tend to be favored are likely to have the value of the corresponding bit of the key for the real cipher. The principle is a bit like the summation of many one-dimensional scans to produce a two-dimensional slice through an object in computer-assisted tomography.

Extensions of Differential Cryptanalysis

The technique of differential cryptanalysis, in addition to being very powerful by itself, has served as a basis for the development of even more powerful techniques, such as those surveyed here and in the next section.

Truncated differentials

It is of course possible that some of the bits of E(A,k) xor E(B,k) will be more likely to match those of Y than others. If one can, in addition, ignore some of the bits of A and B, one has a truncated differential for the cipher being attacked, and this technique, due to Lars R. Knudsen, has been found to be very powerful. (Being able to ignore some bits of A and B may allow two or more truncated differentials to be used together, and this is why it is important.)

Higher-order Differentials

Another important addition to the available techniques deriving from differential cryptanalysis is the use of higher-order differentials, which first appeared in a paper by Xuejia Lai.

A differential characteristic of the type described above, where for a large number of different values of A, B equals A xor X, and the encrypted versions of A and B for a given key, k, are expected to have the relation E(A,k) = E(B,k) xor Y, if a target statement about the key k is true, can be made analogous to a derivative in calculus, and then it is termed that Y is the first derivative of the cipher E at the point X.

A second-order derivative would then be one involving a second quantity, W, such that E(A,k) xor E(B,k) = E(C,k) xor E(D,k) xor Z is expected to be true more often than would be true due to chance, where not only is B = A xor X, but C = A xor W and D = B xor W. In that case, Z is the second derivative of the cipher E at the point X,W. Since xor performs the function of addition and subtraction, the four items encrypted for any A are just lumped together in this case, but if differential cryptanalysis were being performed over another field where the distinction is significant, then Y=E(A+X,k)-E(A,k) and Z=(E(A+X+W,k)-E(A+W,k))-(E(A+X,k)-E(A,k)) would be the appropriate equations to use. This technique is important because a second order derivative can exist at a point for the first coordinate of which no first order derivative exists, or is probable enough to be useful.

And similarly, a third order derivative is derived from the difference of two second order derivatives, based on another constant difference, and so on.

The Boomerang Attack

Recently, a means of improving the flexibility of differential cryptanalysis was discovered by David A. Wagner. Called the boomerang attack, it allows the use of two unrelated characteristics for attacking two halves of a block cipher.



This diagram shows how the attack might work if everything goes perfectly for a particular initial block. The numbered points in the diagram show the steps involved in the attack.

  1. Start with a random block of plaintext. Based on the characteristic known for the first half of the cipher, if we XOR a certain vector with it, called d1 (equal to 00100000 in the diagram), the result after half-enciphering the two plaintext blocks, before and after the XOR, will differ by c1 (equal to 00110110 in the diagram), if what we wish to learn about the key happens to be true.

  2. Since the characteristic applies only to the first half of the cipher, the results after the whole block cipher won't be related. Take those two results, and XOR each one with d2 (equal to 01001011 in the diagram), which is the vector corresponding to the characteristic for the second half of the cipher. In each case, XORing d2 with a ciphertext block is expected to change the result after deciphering halfway by c2 (equal to 00010000 in the diagram), again, if something is true of the key.

  3. With two intermediate results that differ by c1, if each one has c2 XORed to it, the two results of the XOR will still differ by c1. Since this difference now relates to the first half characteristic, it can be seen in the final output, thus indicating the truth or otherwise of two hypotheses about the key.

This increases the potential effectiveness of differential cryptanalysis, because one can make use of characteristics that do not propagate through the complete cipher. Also, certain kinds of added complexities, such as a bit transpose in the middle of the cipher, do not serve as a barrier to this method, since two values differing by an XOR with some value merely differ by an XOR with some other value after a bit transpose.

However, it has its limitations. It only produces a result if both characteristics are present; it does not allow testing for each characteristic independently. Even so, it seems to double the number of rounds a cipher needs to be considered secure.

Since at one end of a sequence of rounds, the precise difference between blocks that is required for the characteristic must be input, it isn't possible directly to cascade this method to break a block cipher into four or more pieces.

Note that any single Feistel round has a large family of "characteristics" that is 100% probable, but which tells nothing about the key, since any pattern that involves leaving the half that is input to the F-function unchanged, but involves an XOR to the half that is XORed with the output of the F-function applies, so one of the things this method can do is allow the use of attacks against the first or last 15 rounds of DES against 16-round DES. Hence, if by some other trick a block cipher with 16 rounds could be broken into 16 pieces like this, one could test for an informative characteristic which applied to any single round.

Vocabulary tasks

Form different parts of speech and translate them.

Cipher


Give as many word combinations as possible and translate them.

Key

Solution


Make the word combinations.

  1. ciphertext-only a) a DES key

  2. flipped b) ciphertext

  3. hill climbing c) aids

  4. trial d) the process

  5. recover e) bit results

  6. mimic f) of discrete elements

  7. incomprehensible g) solution

  8. chain h) algorithm

  9. automated i) encipherment

  10. superencipherment j) key



Complete the text using the terms and word combinations given below.

Running through, a strong encryption algorithm, maps, in parallel, the cryptanalyst, the actual message, computing power


There are several distinct types of cryptoanalytic attack. The type used depends on the type of cipher and how much information ….. has.

Types of cryptoanalytic attacks. A standard cryptoanalytic is to determine the key which … a known plaintext to a known ciphertext. This plaintext can be known because it is standard or because it is guessed. If the plaintext segment is guessed it is unlikelely that its exact position is known however a message is generally short enough for a cryptoanalyst to try all possible positions … . In some systems a known ciphertext-plaintext pair will compromise the entire system however … will be unbreakable under this type of attack.

A brute force attack requires a large amount of … and a large amount of time to run. It consists of trying all possibilities in a logical manner until the correct one is found. For the majority of the encryption algorithms a brute force attack is impractical due to the large number of possibilities.

Another type of brute force attack is a dictionary attack. This essentially involves … a dictionary of words in the hope that the key (or the plaintext) is one of them. This type of attack is often used to determine passwords since people usually use easy to remember words.

In a ciphertext only attack the cryptanalyst has only the encoded message from which to determine the palintext, with no knowledge whatsoever of …. A ciphertext only attack is presumed to be possible, if not easy. In fact, an encryption techniques resistance to a ciphertext only attack is considered the basis for its cryptographic security.


Translate into Russian the following passage. Translate Paragraph 3 in written.

Quantum cryptography is another kind of cryptography in this world. With it, you can create a communications channel where it is impossible to eavesdrop without disturbing the transmission. The laws of physics secure this quantum channel: even if the eavesdropper can do whatever he wants, even if the eavesdropper has unlimited computing power.

According to quantum mechanics, particles don't actually exist in any single place. They exist in several places at once, with probabilities of being in different places if someone looks. However, it isn't until a scientist comes along and measures the particle that it "collapses" into a single location. But you can't measure every aspect (for example, position and speed) of a particle at the same time. If you measure one of those two quantities, the very act of measuring it destroys any possibility of measuring the other quantity.

That can be used to generate a secret key. As they travel, photons vibrate in some direction; up and down, left to right or more likely at some angle. Normal sunlight is unpolarized; the photons vibrate every which way. When a large group of photons vibrate in the same direction they are polarized. Polarization filters allow only photons that are polarized in a certain direction through; the rest are blocked. For example, a horizontal polarization filter only allows horizontally polarized photons through. Turn that filter 90 degrees, and only vertically polarized photons can come through.

Let's say you have a pulse of horizontally polarized photons. If they try to pass through a horizontally polarized filter, they all get through. Slowly turn that filter 90 degrees; the number of photons getting through gets smaller and smaller, until none get through. You'd think that turning the filter just a little will block all the photons, since the photons are horizontally polarized. But in quantum mechanics, each particle has a probability of suddenly switching its polarization to match the filter. If the angle is a little bit off, it has a high probability. If the angle is 90 degrees off, it has zero probability. And if the angle is 45 degrees off, it has a 50 percent probability of passing through the filter.


Translate into English the following passage.

Осуществляя атаку, криптоаналитик может ставить целью решение следующих задач:

  1. Получение открытого текста из зашифрованного.

  2. Вычисление ключа шифрования.

В общем случае, вторая из перечисленных задач является существенно более сложной, чем первая. Однако, имея ключ шифрования, криптоаналитик может впоследствии расшифровывать все данные, зашифрованные найденным ключом. Такая атака (в случае ее успешного осуществления) называется полным раскрытием алгоритма шифрования.

Атаки на алгоритмы шифрования принято классифицировать в зависимости от того набора информации, который имеет злоумышленник перед осуществлением своей атаки.


Grammar

Future Time. Active and Passive Voice.


Active Voice.

Предсказания, прогнозы и обещания выражаются при помощи глагола will. В таких предложениях могут употребляться I think/Perhaps и их эквиваленты.

I think we will finish the project soon.


Going to также может употребляться для прогнозов, если результаты предсказанных действий очевидны или действия обязательно произойдут.

Look! The computer is going to break!

Somebody is going to attack the Intranet.


Future Continuous употребляется для выражения длительных действий, процесса, который будет происходить в определенный момент времени в будущем.

This time next month we’ll be staying in a hotel in Australia.


Future Perfect употребляется для выражения действий, совершенных к определенному моменту в будущем.

By the time he gets there, the conference will have started.


Will и going to употребляются также для выражения намерений. Will выражает намерения, решение о которых принято во время разговора, в качестве ответной реакции на изменяющиеся условия или новую информацию; going to выражает запланированные, обдуманные заранее действия.

We are going to launch a new project. – I will join the work if you don’t mind.


Present Continuous употребляется для выражения запланированных действий в ближайшем будущем.

Im leaving tomorrow afternoon.


Present Simple употребляется различных расписаниях, графиках, афишах.

Our train leaves at 13.32 tomorrow.


После союзов when, until, as soon as употребляются настоящие времена.

We’ll wait until you finish the work.

Grammar tasks.

Test A. Choose the correct form.

  1. We’re sure this approach will/is going to be unique.

  2. We will/are going to buy new equipment.

  3. This laboratory will/is going to work over a speech synthesizer.

  4. I’ve got problems with this program. – I will/am going to help you.


Test B. Complete the sentences with the verbs in brackets and will/going to.

  1. Could you meet our colleagues at the airport? – OK. I (do) it.

  2. I (launch) this program tomorrow.

  3. Where you (stay) in London?

  4. I think biometrics (use) for identification and authentication everywhere.


Test C. Put the verbs in brackets into a suitable form.

  1. Don’t phone between 8.00 and 14.00. We (make) a presentation.

  2. By the time he (arrive) at the office the work already (start).

  3. According to the timetable the bus (arrive) at 8. Chris (come) an hour later.


Passive Voice.

Употребление. Страдательный залог употребляется, когда исполнитель действия неважен или неизвестен. Для говорящего гораздо важнее описать действие, совершенное над объектом. Эта особенность пассивного залога отражается в построении предложений.

Построение предложений в страдательном залоге. Наибольший интерес представляет объект действия, поэтому то, на что направлено действие в страдательном залоге занимает место подлежащего. Исполнитель действия либо не упоминается, либо находится после глагола с предлогом by. Предложения в страдательном залоге строятся по схеме: be+ третья форма глагола в соответствующем времени. Форма глагола be должна соответствовать лицу и числу подлежащего, как показано в примерах.

Future Simple Your luggage will be brought to your room.

Твой багаж принесут в твою комнату.

Future Perfect The letter will have been written by 5 o’clock tomorrow. Письмо будет написано к 5 часам.

Future-in the Past Perfect (He said that) The letter would have been written by 5 o’clock the next day. Он сказал, что письмо будет написано к пяти часам.

Модальные глаголы и конструкции в страдательном залоге подчиняются одной схеме построения: сan, may, must, might, should, have to, ought to, be to – be done.

Например: It must be done. Это обязательно нужно сделать.


Grammar tasks


Test А. Choose the correct form of Passive Voice.

1. In this case unauthorized physical access will prevent/will be prevented/will prevented.

2. Knowing about the risk, one is prepares/will prepared/will be prepared to mitigate it .

3. The underlined secure network services will be installed/will have been installed/is installed in accordance with the operational documentation.


Test B. Put the verbs in brackets in the correct form of Passive Voice.

1. This work (finish) next month.

2. The papers of the conference (translate) into 12 languages.

3. The system (develop) by 2010.

4. It is essential that the process of analyzing and accessing risk (understand) by all sides.


Test C. Put the verbs in brackets in the correct form, Active or Passive Voice.

1. We (meet) at the airport tomorrow.

2. If the BUSINESS module (choose) this (use) to generate a detailed questionnaire appropriate to the system under review.

3. Our consumers (hope) the results of the risk assessment (obtain) soon.


Communication

You need to make a reservation of a room in the hotel. Phone there and discuss it.

Writing


THE ROYAL HOTEL

ROOM RESRVATION REQUEST

Please reserve (insert numbers of the rooms)




Twinbedded




Doublebedded




Single




From night of




To morning of




With breakfast




Without breakfast




Name




Address




Telephone No




Approximate time of arrival






Additional vocabulary

  1. converted unit record equipment (punched card machines) - счётно-перфорационная машина, счётно-аналитическая машина

  2. measure of one's (lack of) altitude – мера, уровень, степень (отсутствия) высоты

  3. brute-force search - исчерпывающий поиск, поиск методом перебора

  4. linear cryptanalysis – линейный криптоанализ

  5. obtain clue – получить ключ

  6. flaw – изъян, дефект, слабое место

  7. summation of many one-dimensional scans – сложение множества одномерных сканограмм

  8. produce a two-dimensional slice through an object – получить двумерное изображение объекта в разрезе

  9. truncated differential – отсеченный дифференциал

  10. calculus – исчисление, дифференциальное и интегральное исчисление, математический анализ

  11. higher-order differential - дифференциал высшего порядка

  12. second-order derivative - производная второго порядка

  13. xor – исключающее «или»

  14. unrelated characteristics - несвязанные характеристики



Unit 5. Steganography.

Vocabulary


What do the following forms and word combinations mean?

Covert communication, coin a term, steganography medium, microdots, size-reduction method, in nonobvious way, semagram (open code), convey a message, doodle, carrier text, overt communication, covert communication, warchalking, cue code, covered (concealment) cipher, grille cipher, null cipher, digital watermarking, nefarious application, financial fraud.
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