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CryptologyApplications of cryptology in private and commercial life. |
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Although people may doubt that they have any personal involvement with cryptology, most adults depend on it to protect their interests or rights in several areas. For example, the personal identity number (PIN) that must be entered into an automated teller machine (ATM), along with a bankcard to corroborate that the card is being used by an authorized bearer, may either be stored in the bank's computers in an encrypted form (as a cipher) or be encrypted on the card itself. The transformation used in this type of cryptography is called one-way; i.e., it is easy to compute a cipher given the bank's key and the customer's PIN but computationally infeasible to compute the plaintext PIN from the cipher, even though the key is known. This is to protect the cardholder from being impersonated by someone who has access to the bank's computer files. Similarly, the communications between the ATM and the bank's central computer are encrypted to prevent a would-be thief from tapping into the phone lines and recording the signals sent to the ATM to authorize the dispensing of cash in response to a legitimate user request and then later feeding the same signals to the ATM repeatedly to deceive it into dispensing money illegitimately. (see also Index: credit card ) |
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Another example is the means used to prevent forgers from counterfeiting winning lottery tickets. Unlike currency, which typically involves state-of-the-art engraving as well as specially compounded inks and watermarked or tagged papers that make counterfeiting difficult, lottery tickets are simply printed on pasteboard much like the admission tickets used by movie theatres and hence are easily counterfeited if one knows what to print on the ticket. Each ticket, however, has two numbers printed on it--one being the identifying number that will be announced when a winner is selected and the other being an encrypted version of this number. Thus, when the winning number is made known, the would-be counterfeiter is unable to print an acceptable forgery unless he also has successfully cryptanalyzed the lottery's cryptosystem. |
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The two preceding examples involve only the use of the authentication feature of a cryptosystem, although secrecy is incidental to the communications between the ATM and the bank's central computer. A novel application that involves all aspects of cryptography are "smart" credit cards, which have a microprocessor built into the card itself. Smart credit cards first saw general use in France in 1984 and promise to supplant in large part the simple plastic cards currently being used. Cryptology is essential to the functioning of these cards in several ways. The user must corroborate his identity to the card each time a transaction is made in much the same way that a PIN is used with an ATM. The card and the card reader execute a sequence of encrypted sign-/countersign-like exchanges to verify that each is dealing with a legitimate counterpart. Once this has been established, the transaction itself is carried out in encrypted form to prevent anyone, including the cardholder or the merchant whose card reader is involved, from eavesdropping on the exchange and then later impersonating either party to defraud the system. This elaborate protocol is carried out in such a way that it is transparent to the user, except for the necessity of entering a PIN to initiate the transaction. |
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There are many other novel areas in which cryptography plays a role in everyday life. In electronic mail, which has had a pilot test in the United States and was already in operation in France by 1984, the only way to provide an "envelope" for the messages is by some form of encryption. Increasingly, the data bases in which personal tax, income, credit-rating information, and other related data are compiled have become shared resources, remotely accessible to read from or to write into, so that cryptographic protection is vital for safeguarding the rights of the individual. Recognizing the threat to national security posed by breaches in computer-system security and attempts to eavesdrop on telecommunications, the U.S. government has taken steps to counteract the problem. Executive approval in 1984 of National Security Directive 145 led to the establishment of the National Telecommunications and Information Systems Security Committee, whose objective is to provide telephone and computer security for the federal government and its contractors. Clearly, information security--and this generally means cryptographically protected information--is one of the major problems faced by postindustrial society, and as such touches almost every aspect of private and commercial life. |
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To cite this page:
"Cryptology: GENERAL CONSIDERATIONS: Applications of cryptology in private and commercial life." Britannica Online. <http://www.eb.com:180/cgi-bin/g?DocF=macro/5001/60/2.html> [Accessed 15 February 1999]. |
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