Computers and Privacy part 3

RSA Public Key Cryptography

Several algorithms are used today for public-key asymmetric encryption. The most widely known is called the RSA algorithm, named after its inventors, Ronald Rivest, Adi Shamir, and Len Adleman. This method is based on multiplying two prime numbers to come up with the key pair. Further mathematical functions are performed after the multiplication to create the actual key pair. It's a simple matter to use a computer to come up with a rather large prime number, but it's a difficult computation task to take the result of this multiplication and the subsequent operations performed and determine which two prime numbers were used to generate it.

If you want to learn more about RSA, visit the Web site for the company founded to market this technology: www.rsasecurity . com. The RSA Security Web site is an excellent resource for encryption techniques overall, but also has a lot of information pertaining to the RSA algorithm, which has been licensed to a large number of software and hardware security providers.

Because of the difficulty in cracking RSA-encrypted data, it has been adopted by a large number of vendors, including Sun, Microsoft, and Novell, and is the most widely used cryptosystem today.

Digital Certificates

Digital certificates are used to bind a person's name (or an identity) to a public key. Certificates, then, must come from a trusted authority. The certificate itself is determined to be valid (that is, it was issued by the certificate authority [CA] it claims to represent) by a digital signature. Because the public key of a CA can be known to anyone, it is a simple computational matter to use the CA's public key to determine that the digital signature is valid. After this is done, the certificate itself can be assumed to contain a valid identity (a user, a corporation, or another entity) associated with a public key. Using a digital certificate, you then can obtain the public key for a person and use it to encrypt data to be sent to that person, who then can use his own private key to read your message.

CAs can be trusted companies on the Internet, or you can act as your own CA in your company. Included with Windows 2000 Advanced Server and the family of Windows 2003 servers, for example, is Microsoft's Certificate Services, which can be used within a company that wants to manage its own digital certificates. If you have branch offices and want to use digital certificates to certify public keys used for communicating over the Internet, you can set up your own certificate servers in your enterprise. Or you can use a commercial company (such as VeriSign) and obtain certificates from a third party.

In practice, it also is possible for a hierarchy of certificate servers to be set up, with a single root server being the most trusted certificate server in your enterprise. Then, child certificate servers are created, which can be validated by the end user because the child certificate server itself has a Certificate from the root server (or another server in the hierarchy leading back to the root server) that validates its certificate. It's all a game of trust, however. If the secret key of the root server's key pair becomes compromised, it's possible to impersonate the certificate server and all security is lost. Most certificates also are issued with an expiration date, which can be used to ensure that new certificates, created using a new key pair, are in use.

For this reason, should you choose to operate your own certificate server(s) in your network, you need to take extreme security precautions to safeguard the private key. Likewise, if you use a third- party commercial certificate service, you need to read the policy of that company to determine how it verifies the identity of the end users that it issues certificates to. For example, a CA might simply verify the email address of the requestor and issue a certificate. For a software publisher, the CA might conduct some kind of background check and require further evidence before it issues certificates to the company. Before you decide to use a commercial service for issuing digital certificates, be sure you investigate the company's policies for both issuing and revoking certificates.

Pretty Good Privacy (PGP)

One of the most popular encryption programs on the Internet for a number of years now has been PGP, originally developed by Phillip Zimmerman. PGP uses public-key cryptography and has been ported to many computer platforms, including Unix, Linux, and, of course, all versions of Windows from Windows NT and Windows 95 onward.

PGP Corporation currently markets the commercial version of PGP. PGP is available in a Universal Series version for network gateways, Whole Disk Encryption for desktop and enterprise systems, command-line for servers and mainframes, and home and professional desktop versions. PGP also maintains a Global Directory of PGP keys, replacing the PGP Keyserver service. A 30-day trial of the home desktop version is available.

PGP has been established as an Internet proposed standard through the Request for Comments (RFC) process. RFC 2440, "OpenPGP Message Format," was written in 1998 and details the specification.

An international site devoted to PGP also can be used to download PGP. Visit the PGPi Project International PGP home page at www pgpi. org/ to learn more about PGP International. The downloads available from this site include support for the following platforms:

Amiga Atari BeOS EPOC (Psion, and so on) MacOS

Newton OS/2 PalmOS Unix MS-DOS

Windows 3.x Windows 95/98/NT Windows Me Windows 2000 Windows XP

As you can see, various operating systems are supported by the International PGP site, which is working to establish PGP as a standard for encryption on the Internet. In addition to the standard PGP package, which provides for a number of applications, such as document encryption and email, a number of other products also are available, such as PGPdisk (for encrypting disks) and PGPphone (for making secure phone calls on the Internet).

The PGPi Project also is making PGP available in various languages, and also is currently translating the documentation. PGPi is a nonprofit organization dedicated to further developing and distributing PGP technology throughout the world. In addition, for some platforms, the source code is available so that you can examine it before compiling it on your system.

Expressing the Role of the User by Creating an Archetypal Character

Identifying an average user of the Internet, is at best implausible, and, more probably, impossible; but this does not exonerate systems designers from trying. The previous section described how a research method was devised to establish purpose, for the design of a novel IS, but mentioned at the outset how it is the wants or needs of the end-user that must always be the overriding purpose of any such system. Consequently, the method, although sufficient for ensuring compatibility between system and organization, was not enough to guarantee end-user satisfaction. As work began on prototype development, it became apparent that identification of end-users of the system needed further clarification.

Discussion revealed that the organization had very clear perspectives on some members of the public that take an interest in the heritage. They could be described as those that already made use of its services, its current customer base, and a very concrete understanding of their needs and wants already existed. Accordingly, there was a feeling that the customer, or potential user, was already known, and did not therefore need to be discovered, nor included in either development or system-testing. However,because the PastScape project was exploring an untapped area, its resulting application had the potential to reach a whole new customer base, customers whose identities were not yet discovered. Although internal belief and external reality may have been a perfect match, there was no evidence to assert this possibility, and without a concrete external user to target, the system risked only satisfying an internalized viewpoint, without necessarily improving the organization's dissemination of information. Furthermore, there is always a danger, with such an internalised viewpoint, that the wrong emphasis can be placed on decisions; for example, regarding which particular dataset should take advantage of a new, and potentially advantageous, system.

Many organizations are structured in such a way that different sections, divisions or departments have responsibility, and therefore ownership, for different elements of the organization's data. This carries with it the possibility that a dataset will be chosen according to some sort of purely internal motivation, rather than for the benefit of an intended user. In an attempt to resolve this issue satisfactorily, i.e. to promote wider internal acceptance of the principles of user-centred design, two different approaches were established. The first was to compose a "typical" user; the second was to explain the correlation between the potential new system and certain current business practices. These two approaches are outlined here:

The Intelligent 12-year-old

Because the perfect typical, or average, user does not, unfortunately, exist, early usability experiments for this project were conducted with the involvement of a variety of potential user-group representatives. The test- subject volunteer force (some 48 people, half of whom were males, and the other half, females) was composed of equal ratios of: heritage professionals; computer experts; lay people with no expertise in either heritage or computing; and, children aged between 9 and 11 years. However, in everyday discussions with EH staff it was impractical, to say the least, to try and explain that every element of the system was being designed to disseminate information to this convoluted cross section of society. Thus, all four types, and both genders, became assimilated into a single, easily explained, "intelligent 12-year-old". From the moment that this creation took life, explaining or rationalising any element of the system, to almost anyone, took on a new and surprising simplicity and clarity. Most people seemed to naturally understand what was meant by an intelligent 12-year-old, had no problem seeing why such a character had arisen from our collection of test subjects, and, perhaps most interestingly, accepted that such a persona was appropriate, as an "average" user of the Internet with a possible interest in heritage matters.

From Data to Information

The second approach taken, to demonstrate the importance of a target audience, was to clarify the functionality of a usable system by relating it to more easily recognised, non-IS, business functions. It was necessary, at various stages, to attain approval from people within EH who were well acquainted with dealing with the public, and whose natural responses revolved around familiar business processes, usually from a non-IT viewpoint, but often with an informed knowledge of web or IS principles. Drawing on the results of the initial analytical method, and through discussion with internal staff, a picture was revealed of some of the business practices that were already being used to disseminate database information to the public, and to other heritage professionals. The area of the organization's business structure that was most relevant to the project at that time, centred around EH's National Monuments Record Centre (NMRC) where members of the public could request heritage information. An enquiry would elicit a search by a team of in-house professionals, using various national databases and archives, and the results would be supplied to the enquirer. Essential to this process, which is of course an information system, are: the existence of data; an understanding of the data; an interpretion of the user's requirement; and delivery of appropriate information. Appropriate, of course, to the end-user. This, the process of turning data into information, is illustrated in Fig. 8.1. Within the NMRC, the in-house professionals perform this complex task by interpreting what the user wants, being able to understand the terminology and structure of the data, and then by presenting a suitable end-product.

Taking this already-understood process, or service to the use, and equating it to what a good IS should provide, was a useful ally in the explanation of the new interface, especially to those who were regular users of the Internet; many web-sites fail to provide this absolutely essential service, instead simply making raw data available. Such sites are not truly information systems, they are data storage systems with multiple-user access.