An object is referenced by its unique name in

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Unformatted text preview: ard and checks to see if the card produced belongs to an authorized user. Obviously, security can be ensured only if the item to be produced is unforgeable and safely guarded. 3. Proof by Property. In this approach, the system is designed to verify the identity of a user by measuring some physical characteristics of the user that are hard to forge. The measured property must be distinguishing, that is, unique among all possible users. For example, a special device (known as a biometric device) may be attached to each terminal of the system that verifies some physical characteristic of the user, such as the person's appearance, fingerprints, hand geometry, voice, signature. In deciding the physical characteristic to be measured, an important factor to be considered is that the scheme must be phycologically acceptable to the user community. Biometric systems offer the greatest degree of confidence that a user actually is who he/she claims to be, but they are also generally the most expensive to implement. Moreover, they often have user acceptance problems because users see biometric devices as unduly intrusive. In practice, a system may use a combination of two or more of these authentication methods. 'For example, the authentication mechanism used by automated cash-dispensing machines in banks usually employs a combination of the first two approaches. That is, a user is allowed to withdraw money only if he or she produces a valid identification card and specifies the correct password corresponding to the identification number on the card. To provide good security with password-based authentication, it is important that passwords are kept secret and passwords are chosen in such a manner that they are difficult to guess. Access Control Once a user or a process has been authenticated, the next step in security is to devise ways to prohibit the user or the process from accessing those resources/information that he/she/it is not authorized to access. This issue is called authorization and is dealt with by using access control mechanisms. When talking about access control in co...
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This document was uploaded on 04/07/2014.

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