Английский язык: Аннотирование и реферирование текста

215 Positive Identification of Users . A computer system needs a sure way of identifying the people who are authorized to use it. The identification procedure has to be quick, simple, and convenient. It should be so thorough that there is little chance of the computer being fooled by a clever imposter. At the same time, the computer must not reject legitimate users. Unfortunately, no identification system cur- rently in use meets all these requirements. At present, signatures are widely used to identify credit-card holders, but it takes an expert to detect a good forgery. Sometimes even a human expert is fooled, and there is no reason to believe that a com- puter could do any better. A variation is to have the computer analyze a person's hand movements as he signs his name instead of analyzing the signature it- self. Advocates of this method claim that different persons' hand movements are sufficiently distinct to identify them. And while a forger might learn to duplicate another person's signature, he probably would not move his hand exactly the way the person whose signature he was forging did. Photographs are also sometimes used for identification. But, people find it inconvenient to stop by a bank or credit card company and be photographed. Companies might lose business if they made the pictures an absolute requirement. Also, photographs are less useful these days, when people frequently change their appearance by chang- ing the way they wear their hair. Finally, computer programs for ana- lyzing photographs are still highly experimental. Cash-dispensing systems often use two identification numbers: one is recorded on a magnetic stripe on the identification card, and the other is given to the cardholder. When the user inserts his card into the cash-dispensing terminal, he keys in the identification number he has been given. The computer checks to see that the number recorded on the card and the one keyed in by the user both refer to the same person. Someone who stole the card would not know what number had to be