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Operates, popular, as, using, considerable, is combined1. The Data Encryption Standard remains quite … and used in different applications. 2. Many block ciphers have been designed and released, with … variation in quality. 3. Stream ciphers create a long stream of key material which … with the plaintext. 4. A hidden internal state in a stream cipher changes as the cipher …. 5. … the secret key material, that internal state is initially set up. 6. Block ciphers can be used … stream ciphers.
6. Read the text and name key points raised in it. Symmetric Key Algorithm
Symmetric-key cryptography refers to encryption methods in which both the sender and receiver share the same key (or, less commonly, in which their keys are different, but related in an easily computable way). This was the only kind of encryption publicly known until June 1976. The modern study of symmetric-key ciphers relates mainly to the study of block ciphers and stream ciphers and to their applications. A block cipher is, in a sense, a modern embodiment of Alberti’s polyalphabetic cipher: block ciphers take as input a block of plaintext and a key, and output a block of ciphertext of the same size. Since messages are almost always longer than a single block, some method of knitting together successive blocks is required. Several have been developed, some with better security in one aspect or another than others. They are the modes of operation and must be carefully considered when using a block cipher in a cryptosystem. The Data Encryption Standard (DES1) and the Advanced Encryption Standard (AES2) are block cipher designs which have been designated cryptography standards by the US government (though DES’s designation was finally withdrawn after the AES was adopted). Despite its deprecation as an official standard, DES (especially its still-approved and much more secure triple-DES variant) remains quite popular; it is used across a wide range of applications, from ATM3 encryption to e-mail privacy and secure remote access. Many other block ciphers have been designed and released, with considerable variation in quality. Many have been thoroughly broken. Stream ciphers, in contrast to the “block” type, create an arbitrarily long stream of key material, which is combined with the plaintext bit-by-bit or character-by-character, somewhat like the one-time pad. In a stream cipher, the output stream is created based on a hidden internal state which changes as the cipher operates. That internal state is initially set up using the secret key material. RC44 is a widely used stream ciphe. Block ciphers can be used as stream ciphers. Cryptographic hash functions are a third type of cryptographic algorithm. They take a message of any length as input, and output a short, fixed length hash which can be used in (for example) a digital signature. For good hash functions, an attacker cannot find two messages that produce the same hash. MD45 is a long-used hash function which is now broken; MD5, a strengthened variant of MD4, is also widely used but broken in practice.
Notes: 1DES – Data Encryption Standard – стандарт шифрования данных; 2AES – Advanced Encryption Standard – улучшенный стандарт шифрования, стандарт AES; 3ATM – Automatic Teller Machine – банкомат; 4RC4 – Rivest cipher 4 – (потоковый, поточный) шифр Райвеста 4, (Потоковый шифр с ключом переменного размера, его алгоритм базируется на использовании случайных перестановок. Шифр может надёжно служить для безопасной (защищённой) связи и обмена секретными данными); 5MD – Message Digest – алгоритм MD (Серия алгоритмов (MD2, MD4, MD5) разработана Рональдом Райвестом для приложений, использующих цифровую подпись. MD4 используется в системе безопасности Windows NT, чтобы из битовой последовательности произвольной длины получить уникальную битовую последовательность конечной длины.)
7. Read the following statements and say whether they are true or false. Correct the false ones. 1. Symmetric-key cryptography refers to the encryption methods in which the sender and receiver share either different keys or the same key. 2. A block of plaintext and a key are output for block ciphers. 3. Some methods of connecting together successive blocks have been developed longer because messages are usually shorter than a single block. 4. Some method of separating successive blocks is necessary in block ciphers. 5. When using a block cipher, there’s no need to take into account the modes of operation. 6. Symmetric-key cryptography was a single type of encryption that was popular before 1976.
8. Match parts A and B to complete the sentences
9. Read paragraph 2 and describe the principles of block cipher operation.
10. Using information of paragraph 3 make the description of US cryptography standards.
11. Read paragraph 4 and make description of stream ciphers.
12. Using information of paragraph 5 explain the essence of cryptographic hash functions.
13. Make an outline of the text.
14. Make a short summary of the text in a written form using your outline. The phrases given below will help you. 1. The text deals with …. 2. … are discussed. 3. They include …. 4. It shows …. 5. To sum up …. 6. Intensive efforts have been devoted to …. 7. The efforts continue in the direction of ….
Part B
15. Study the words and word combinations to the following text. Point out the main question of it. Security, objectives, privacy, data integrity, authentication, non-repudiation.
16. Read the text and write out key words and phrases revealing the contents of the paragraphs.
17. Read the text and find out the topical sentences of the paragraphs.
18. Find 1 or 2 sentences which can be omitted as inessential in each logical part.
19. Look through the text and choose the best title. 1. Cryptographic Secrecy 2. Cryptographic Procedures 3. The Concept of Information 4. Cryptographic Goals Text B
Of all the information security objectives the following four form a framework upon which the others will be derived: privacy or confidentiality; data integrity; authentication; and non-repudiation. Confidentiality is a service used to keep the content of information from all but those authorized to have it. Secrecy is a term synonymous with confidentiality and privacy. There are numerous approaches to providing confidentiality, ranging from physical protection to mathematical algorithms with render data unintelligible. Data integrity is a service which addresses the unauthorized alteration of data. To assure data integrity, one must have the ability to detect data manipulation by unauthorized parties. Data manipulation includes such things as insertion, deletion, and substitution. Authentication is a service related to identification. This function applies to both entities and information itself. Two parties entering into a communication should identify each other. Information delivered over a channel should be authenticated as to origin, date of origin, data content, time sent, etc. For these content reasons this aspect of cryptography is usually subdivided into two major classes: entity authentication and data origin authentication. Data origin authentication implicitly provides data integrity (for if a message is modified, the source has changed). Non-repudiation is a service which prevents an entity from denying previous commitments or actions. When disputes arise due to an entity denying that certain actions were taken, a means to resolve the situation is necessary. For example, one entity may authorize the purchase of property by another entity and later deny such authorization was granted. A procedure involving a trusted third party is needed to resolve the dispute. A fundamental goal of cryptography is to adequately address these four areas in both theory and practice. Cryptography is about the prevention and detection of cheating and other malicious activities.
20. Sum up the text using the key words and word combinations and the topical sentences.
21. Find the sentences containing: a) the main idea of the text; b) specifying information.
22. Express your attitude to the facts given in the text. You may use the following phrases: - it is full of interesting information …. - I find the text rather/very cognitive …. - I’ve learnt a lot …. - I don’t agree with it ….
23. Say which facts presented in the text you ve already been familiar with.
24. Make a questionnaire to the text and interview your partner on the problem raised in the text.
Part C
25. Read the title of text and say what information is presented in it.
26. Scan the following text and say what problems are described in it.
From the History of Cryptography
Cryptography has a long and fascinating history. The most complete non-technical account of the subject is Kahn’s The Codebreakers. This book traces cryptography from its initial and limited use by the Egyptians some 4000 years ago, to the twentieth century where it played a crucial role in the outcome of both world wars. Completed in 1963, Kahn’s book covers those aspects of the history which were most significant (up to that time) to the development of the subject. The predominant practitioners of the art were those associated with the military, the diplomatic service and government in general. Cryptography was used as a tool to protect national secrets and strategies. The proliferation of computers and communications systems in 1960s brought with it a demand from the private sector for means to protect information in digital form and to provide security services. Beginning with the work of Feistel at IBM in the early 1970s and culminating in 1977 with the adoption as a U.S. Federal Information Processing Standard for encrypting unclassified information, DES, the Data Encryption Standard, is the most well-known cryptographic mechanism in history. It remains the standard means for securing electronic commerce for many financial institutions around world.
27. Find the following information in the text: a) the main fields of cryptography usage; b) the most common cryptographic mechanism.
28. What can you add to the text using your knowledge in the field of cryptography?
Unit VII New electronics: research and development Word List
Part A 1. Read the following words in each line and define their roots. Translate the words into Russian: 1) operate, operation, operator, operative; 2) reduction, reductive, reduce; 3) equip, equipment, equipped; 4) develop, developer, development; 5) similar, similarity, similarly.
2. Fill in the gaps with the words derived from the words in brackets. 1. Smuggling is a (grow) problem. 2. The screening systems available are typically bulky, expensive and require ultra high (sensitive) as the sensor is remote from the cargo. 3. The Ferret will reduce the need for customs and security officials to enter or unpack freight (contain). 4. The Ferret is (equip) with a suite of sensors that is more sensitive than any currently employed in conventional cargo scanners. 5. UK researchers have made huge advancements in terms of miniaturisation and improving the (capable) of the sensors.
3. Find out the equivalents to the following words and word combinations in paragraphs 1 and 2 of the text below. Разнообразие, системы тщательной проверки, требовать, груз, риск потенциального заражения, крайняя необходимость, альтернативное решение, недостатки, взрывчатые вещества, рентгеновские лучи.
4. Fill in the gaps with one of the following words:   Конфликты в семейной жизни. Как это изменить? Редкий брак и взаимоотношения существуют без конфликтов и напряженности. Через это проходят все...  Что будет с Землей, если ось ее сместится на 6666 км? Что будет с Землей? - задался я вопросом...  ЧТО ПРОИСХОДИТ, КОГДА МЫ ССОРИМСЯ Не понимая различий, существующих между мужчинами и женщинами, очень легко довести дело до ссоры...  ЧТО И КАК ПИСАЛИ О МОДЕ В ЖУРНАЛАХ НАЧАЛА XX ВЕКА Первый номер журнала «Аполлон» за 1909 г. начинался, по сути, с программного заявления редакции журнала... Не нашли то, что искали? Воспользуйтесь поиском гугл на сайте:
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