2. Provide definitions in the context of protecting information in computers:

Access

Authenticate

Authorize

Certify

Encipherment

Password

Privacy

Protection

Security

Check them with the Glossary given at the end.

3. Answer the questions to the text and perform the tasks.

1. Give your own examples of systems requiring protection of information

2. What is the main difference between the notions protection and security?

3. Span the needs for organizational and personal privacy.

4. What are the three categories of the potential security violations? Describe them.

5. Why can release, modification, or denial of use occur contrary to the desire of

the person?

6. Give examples of security techniques sometimes applied to computer systems.

7. What are the other definitions of the terms protection and authentication?

8. Why are these terms considered to provide a narrow view of information

security?

4. Discuss the basic principles of information protection.

GRAMMAR REVISION

1. Use the correct tense form.

This story happened to Mr. Brown who (was living, lived, had lived) in the suburbs of one of the towns in England. One evening he (walked, was being walked, was walking) home from the railway station. The road (had been, was, being) dark and lonely. Suddenly he heard someone (was approaching, approached, approaching) him from behind and thought he (being followed, was being followed, was followed). Mr. Brown (was, had been, being) terribly frightened and started (run, ran, running). The footsteps still followed him. The man ran into an old cemetery and threw himself on the grass near one of the graves.

Lying there Mr. Brown thought, " If he (came, was coming, comes) here there (will be, is, was) no doubt he ( wanted, wants, will want) to rob me."

The man behind really came there too. Mr. Brown wondered what he (wants, wanted, will want) and why he (is following, had followed, was following) him.

The stranger said that he (was going, went, had gone) to Mr. Robertson's and he had been told that Mr. Brown (was living, lived, had lived) next door to the Robertsons. That's why he decided to follow him. And the stranger thought it was a sort of exercise Mr. Brown (was using, used, is using) to do in the evenings.

2. Put the questions to the following sentences.

1. The weather was stormy yesterday. (What?)

2. A lot of hamburgers are eaten in the USA. (How many?)

3. Ann has just come back from London. (When?)

4. He had to borrow some money. (Why?)

5. They have been quarrelling since morning. (How long?)

6. Stephen and Paul lead an adventurous life. (Who?)

7. We used to go to the theatre on Friday nights. (Where?)

8. Dick won't be able to join us tomorrow. (Why?)

9. She speaks English very well. (How?)

3. Andrea is giving a talk to her class at the language school about her first few weeks in Britain. Complete what she says. Put the verbs in brackets into the correct tense.

I.............................(arrive) about eight weeks ago. I..............................(not be) to Britain before, so I..............................(not know) what to expect. My friends Vince and Sue.............................. (meet) me at the airport. They..............................(wait) for me when I..............................(come) out of the arrivals gate. I..............................(be) very pleased to see them. You see, my cousin Carmen.............................(come) to stay with Sue the summer before last, but there..............................(not be) anyone to meet her at the airport, because

Sue.............................(have) an accident. Anyway, as I said, I..............................(be) here for about two months now. I..............................(learn)

a lot of English in that time and I..............................(do) a lot of things. I..............................(be) to London a Few times and last weekend I

..............................(go) to Oxford to see Sue. While Sue............................(show) me some of the colleges. I..............................(see) some people from my town in. Argentina. They..............................(arrive) in England the day before. We

..............................(be) all so surprised. We..............................(can't) believe it....

4. Supply some, any, no for the following sentences.

1. If you have ... news, call me back. 2. She helped borrow ... more money. 3. There is hardly ... place in this house where we can talk alone. 4. ... boy at the school had ever taken a scholarship to the university. 5. It meant real hardship to my mother unless I earned ... money at once. 6. My mother hoped that perhaps the school had ... funds to give me a grant. 7. It was unlikely that ... of the guests would take particular notice of it. 8. They understood each other without ... words. 9. "Let's go back home. It's already late." "I'd rather stay out a little longer." "I suppose we've got to go home ... time." 10. There isn't ... boot-polish in this tin. 11. You have ... fine flowers in your garden. 12. Go and ask him for ... more paper, I haven't ... in my desk. 13. Later we had ... tea. 14. He wants ... more pudding. You can take it away. 15. There are ... matches left. We must buy ... .16. I wouldn't go to his concert. He is ... pianist. 17. ... time ago I read his story in a magazine. 18. I don't think there is ... milk left in the jug. 19. ... student can answer the question.

 

Summarize the text.

Text B

Functional Levels of Information Protection.

Many different designs have been proposed and mechanisms implemented for protecting information in computer systems. One reason for differences among protection schemes is their different functional properties--the kinds of access control that can be expressed naturally and enforced. It is convenient to divide protection schemes according to their functional properties. A rough categorization is the following.

a) Unprotected systems: Some systems have no provision for preventing a determined user from having access to every piece of information stored in the system.

b) All-or-nothing systems: These are systems that provide isolation of users, sometimes moderated by total sharing of some pieces of information. If only isolation is provided, the user of such a system might just as well be using his own private computer, as far as protection and sharing of information are concerned. More commonly, such systems also have public libraries to which every user may have access. In some cases the public library mechanism may be extended to accept user contributions, but still on the basis that all users have equal access.

c) Controlled sharing: Significantly more complex machinery is required to control explicitly who may access each data item stored in the system. For example, such a system might provide each file with a list of authorized users and allow an owner to distinguish several common patterns of use, such as reading, writing, or executing the contents of the file as a program.

d) User-programmed sharing controls: A user may want to restrict access to a file in a way not provided in the standard facilities for controlling sharing. For such cases, and a myriad of others, a general escape is to provide for user-defined protected objects and subsystems. A protected subsystem is a collection of programs and data with the property that only the programs of the subsystem have direct access to the data (that is, the protected objects). Access to those programs is limited to calling specified entry points. Thus the programs of the subsystem completely control the operations performed on the data.

e) Putting strings on information: The foregoing three levels have been concerned with establishing conditions for the release of information to an executing program. The fourth level of capability is to maintain some control over the user of the information even after it has been released. Such control is desired, for example, in releasing income information to a tax advisor; constraints should prevent him from passing the information on to a firm which prepares mailing lists. The printed labels on classified military information declaring a document to be "Top Secret" are another example of a constraint on information after its release to a person authorized to receive it. There is a consideration that cuts across all levels of functional capability: the dynamics of use. This term refers to how one establishes and changes the specification of who may access what. At any of the levels it is relatively easy to envision (and design) systems that statically express a particular protection intent. But the need to change access authorization dynamically and the need for such changes to be requested by executing programs introduces much complexity into protection systems.

In many cases, it is not necessary to meet the protection needs of the person responsible for the information stored in the computer entirely through computer-aided enforcement. External mechanisms such as contracts, ignorance, or barbed wire fences may provide some of the required functional capability. This discussion, however, is focused on the internal mechanisms.

Supplementary reading.

Text C

Design Principles.

Whatever the level o f functionality provided, the usefulness of a set of protection mechanisms depends upon the ability of a system to prevent security violations.. Design and construction techniques that systematically exclude flaws are the topic of much research activity, but no complete method applicable to the construction of large general-purpose systems exists yet. This difficulty is related to the negative quality of the requirement to prevent all unauthorized actions.

In the absence of such methodical techniques, experience has provided some useful principles that can guide the design and contribute to an implementation without security flaws. Here are eight examples of design principles that apply particularly to protection mechanisms.

a) Economy of mechanism: Keep the design as simple and small as possible. As a result, techniques such as line-by-line inspection of software and physical examination of hardware that implements protection mechanisms are necessary. For such techniques to be successful, a small and simple design is essential.

b) Fail-safe defaults: Base access decisions on permission rather than exclusion. This principle, suggested by E. Glaser in 1965, means that the default situation is lack of access, and the protection scheme identifies conditions under which access is permitted. It applies both to the outward appearance of the protection mechanism and to its underlying implementation.

c) Open design: The design should not be secret. The mechanisms should not depend on the ignorance of potential attackers, but rather on the possession of specific, more easily protected, keys or passwords. This decoupling of protection mechanisms from protection keys permits the mechanisms to be examined by many reviewers without concern that the review may itself compromise the safeguards. In addition, any skeptical user may be allowed to convince himself that the system he is about to use is adequate for his purpose.

d) Psychological acceptability: It is essential that the human interface be designed for ease of use, so that users routinely and automatically apply the protection mechanisms correctly. Also, to the extent that the user's mental image of his protection goals matches the mechanisms he must use, mistakes will be minimized. If he must translate his image of his protection needs into a radically different specification language, he will make errors.

UNIT 2

Read and translate the text.

Text А