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Security: Internet

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Introduction
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Security in General
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Privacy
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Integrity
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Usability
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Can I Use Cryptographic Software?

Computer Security Primer-The Internet:

Privacy

First a quick statement about privacy:
Don't count on it. Don't trust your life to it.

Your computer, like anything you write down, or speak in public could be copied, or later repeated. Your data, stored on another computer, such as that provided on a shell account at your ISP, is completely out of your control. This does not impugn the honesty of your ISP, nor even of employees there. It is merely a statement of fact. Whereever in the world your data is sitting at any given time - unless it is on your computer, disconnected from any network, and within your physical supervision - there is a chance that someone else could have access to it. Because the screen of your computer is, in effect, essentially a low-power radio transmitter, even what you look at on your screen in privacy could be viewed by others if it is worth their while to use expensive and complex methods of capturing that information.

By definition, your data is that data that you created, or that should be in your control and deals with you or your personal or commercial business.

That definition means that when you make a purchase with a credit card, your data is out of your control. When you make a purchase from anyone who keeps records of that purchase, your data is out of your control. When you pay taxes, or register to vote, or have an untoward encounter with a public official or with the police, however trivial, your data is out of your control. Many of these things are beyond your capacity to prevent. What you type into your own computer should not be beyond your capacity to reasonably safeguard against normal hazards. When you use a public access terminal, even what may remain on the local computer when you leave is unguarded information. You should realize that, and use it accordingly.

Before you Connect

Many things we do with computers are personal, today. It may be the writing of a letter, calculating and displaying with a spreadsheet, even playing a game is really usually nobody else's business. But, it is possible for us to safeguard that information, such that even if another gains access to our computer it is difficult if not impossible for them to ``get to'' our data. The tool used for this is a computer program which uses encryption. Encryption merely takes the data and stores it in a different format. That encrypted format is unavailable to anyone without the correct passphrase or password using the same, or compatible program. Also, not all encryption is equal in strength, just as not all locks on a door are of equal strength.

The use of strong encryption is possible in most of the world today. Some of the strongest available escaped US export restrictions several years ago, and is maintained in a world-wide volunteer effort. In most of the world, it is legal to use it. Noteable exceptions are some of the republics from the former Soviet Union, where government sponsored encryption must be used if any is used, and in France, where special government permission is required. China, Iran and Iraq seemingly also have restrictions on all use of encryption technology. This is not a guarantee that it is legal where you, the reader, is located, but rather the result of occasional doublechecking. One listing is maintained within the various PGP distributions.

But the use of such encryption technology is only as solid as your practices. If you make your pass-phrase easily guessable, it is like using a door lock with a simple (skeleton) key. If you leave it written down, it is like leaving your keys laying around for someone to borrow. If you only sometimes use it, it is like leaving the door unlocked at times. And because this is about privacy, if you leave copies around which are not encrypted, even in a WINDOWS\TEMP\ file or comparable place on other system-types, it is the same as keeping private papers in a safe, with a copy laying on the desk.

Shell Accounts

... and other things on the net depend upon security on your end, on the other end (the remote site), and even in between.

Even though, we know that data left on your shell account are outside your control, it does not mean that you will wish to leave such things open to everyone. Usually, your login is protected by a password or pass-phrase. Yet, that password MIGHT be, and today, normally is sent without that encryption we spoke of above, between your computer, where you type it, and the account on your ISP's machine. This means that anything between your machine and that machine, including your password, could be ``sniffed'' by anyone with physical access to any part of the network between your keyboard and the software at your ISP which receives it. But even with this hole in security, it is probable that only the telephone lines between you and your ISP, and perhaps your ISP's internal network are between you and your shell or E-Mail account, when you are at home or your normal office. If you use that account from a public access terminal, or across the net from a friend or associate's computer, however, it may be that a copy could even be stored as you type it, either within this other computer you are using, or somewhere between it and your account. Only you can determine if this is too great of a risk. For most people it is not too great a risk. Yet other technologies are available even for a shell login, if your ISP supports it and compatible software is available for your computer operating system, such as ``secure shell''.

Web Pages - Secure?

When entering credit card numbers to place an order through a web page, for example, it may, indeed, be too great of a risk, to allow that information to be captured by someone else. While a public access terminal may be just fine for casual use, it may not be the place you wish to enter your credit card number into a web page. Also, not all web pages are the same, and telling the difference is reasonably easy, but requires you to understand it. We'll cover this technical point first, then touch on some things that may seem obvious.

Two main ``protocols'' are used on the World Wide Web. You may notice them in the slot on your browser that displays web addresses. Each URL has several letters at the front which identify the ``scheme'' or ``protocol''. http is the one most often seen, and it is so common, that some browsers will insert it if you do not. This is actually an acronym for HyperText Transport Protocol. A second adds the letter s to that (S for Secure). Plain http is much like the plain E-Mail we spoke of above. There is no security, except that there may be noone in a position to look, or with the interest to look.

With https, though, the data passed in both directions between your computer and the server your computer communicates with is encrypted. This means that someone in between should not be able to decypher and view the content. This is not absolute, however. Some of the servers released prior to mid-June 1998 (which at this writing includes most), had some debugging code inadvertantly left in place, which allowed their security to be broken. Similarly, some servers are themselves insecure (like locking the door and leaving the window wide open). Hence, according to the truism stated above - when the data leaves your control, it is out of your control. It should be safer if transferred via https whether or not a window on your browser pops up to tell you about it, or if you check the security of the current page with a menu option in your browser. Much more information is available elsewhere, as the actual strength of the encryption used may also vary.

Now for the obvious part. When you send such sensitive information to someone else, you must judge their fitness and reliability to both properly protect it, and to use it properly. Anything in a computer can be easily copied. If you know the business or person, or have done business with them in the past, you may know something about the risks, or at least be able to form an opinion. Size does not imply reliability!


This story Copyright © Bruce Gingery. All rights reserved.

Copyright © 1996, 1997, 1998 Dr. Raj Mehta. All rights reserved.