Complete the text using the words 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.

11. Complete the text.

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

• …
  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 … ciphertext.

• In
  those of the 56 cases where the flipped bit results in the
  ciphertext produced … 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 … algorithm, where the number of bits by
which a trial encipherment differs from the actual ciphertext is a
measure of one’s (lack of) altitude.

12. Translate into English the following passage.

Осуществляя
атаку, криптоаналитик может ставить
целью решение следующих задач:

1. Получение открытого
   текста из зашифрованного.

1. 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.

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Task 1

Match the words with their opposites. Then write a sentence with each word combination.

1. huge

A. patiently

2. unimportant

B. ability

3. impatiently

C. valuable

4. excluded

D. significant

5. inability

E. ugly

6. beautiful

F. private

7. responsible

G. included

8. public

H. irresponsible

9. worthless

I. tiny

Task 3

Complete the text with the given words.

landscapes, watercolours, exhibition, skilled, drawings, still lifes, portraits, oils, display, techniques

Last weekend, my friend Larry and I went to an art 1. _______________. There were a variety of paintings and 2. _______________ on 3. _______________. There were true-to-life 4. _______________ of famous people, beautiful 5. _______________ of waterfalls and valleys, and also 6. _______________. For landscapes, most artists used 7. _______________, but some of them worked in 8. _______________. 9. _______________ artists use interesting 10. _______________ to show the shadows.

Task 4

Fill in the gaps with comparatives and superlatives.

By far, this drawing is _________________ (valuable) in my collection.
This gallery is _________________ (busy) one I’ve ever been to!
The colours on this painting are _________________ (warm) than on that one.
That was the _________________ (bad) technique I’ve ever seen.
Lorna is _________________ (talented) sculptor I’ve seen. She makes sculptures out of clay.
The lines in Picasso’s pictures were drawn much _________________ (accurately) than I expected.
Which of these two vases do you find _________________ (good)?
I think that painting with watercolours must be _________________ (difficult) than painting with oils.
You should study _________________ (carefully) to improve your skills.
This picture is _______________ (great) I’ve ever seen.