http://en.wikipedia.org/wiki/Computer_security
The technologies of computer security are based on Link Removed due to 404 Error. As security is not necessarily the primary goal of most computer applications, designing a program with security in mind often imposes restrictions on that program's behavior.
There are several approaches to Link Removed due to 404 Error in Link Removed due to 404 Error, sometimes a combination of approaches is valid:
There are various strategies and techniques used to design security systems. However there are few, if any, effective strategies to enhance security after design. One technique enforces the Link Removed due to 404 Error to great extent, where an entity has only the privileges that are needed for its function. That way even if an Link Removed due to 404 Error gains access to one part of the system, fine-grained security ensures that it is just as difficult for them to access the rest.
Furthermore, by breaking the system up into smaller components, the complexity of individual components is reduced, opening up the possibility of using techniques such as Link Removed due to 404 Error to prove the correctness of crucial software subsystems. This enables a Link Removed due to 404 Error to security that works well when only a single well-characterized property can be isolated as critical, and that property is also assessible to math. Not surprisingly, it is impractical for generalized correctness, which probably cannot even be defined, much less proven. Where formal correctness proofs are not possible, rigorous use of Link Removed due to 404 Error and Link Removed due to 404 Error represent a best-effort approach to make modules secure.
The design should use "Link Removed due to 404 Error", where more than one subsystem needs to be violated to compromise the integrity of the system and the information it holds. Defense in depth works when the breaching of one security measure does not provide a platform to facilitate subverting another. Also, the cascading principle acknowledges that several low hurdles does not make a high hurdle. So cascading several weak mechanisms does not provide the safety of a single stronger mechanism.
Subsystems should default to secure settings, and wherever possible should be designed to "fail secure" rather than "fail insecure" (see Link Removed due to 404 Error for the equivalent in safety engineering). Ideally, a secure system should require a deliberate, conscious, knowledgeable and free decision on the part of legitimate authorities in order to make it insecure.
In addition, security should not be an all or nothing issue. The designers and operators of systems should assume that security breaches are inevitable. Full Link Removed due to 404 Error should be kept of system activity, so that when a security breach occurs, the mechanism and extent of the breach can be determined. Storing audit trails remotely, where they can only be appended to, can keep intruders from covering their tracks. Finally, Link Removed due to 404 Error helps to ensure that when bugs are found the "Link Removed due to 404 Error" is kept as short as possible.
The technologies of computer security are based on Link Removed due to 404 Error. As security is not necessarily the primary goal of most computer applications, designing a program with security in mind often imposes restrictions on that program's behavior.
There are several approaches to Link Removed due to 404 Error in Link Removed due to 404 Error, sometimes a combination of approaches is valid:
- Trust all the software to abide by a security policy but the software is not trustworthy (this is Link Removed due to 404 Error).
- Trust all the software to abide by a security policy and the software is validated as trustworthy (by tedious branch and path analysis for example).
- Trust no software but enforce a security policy with Link Removed due to 404 Error that are not trustworthy (again this is Link Removed due to 404 Error).
- Trust no software but enforce a security policy with trustworthy mechanisms.
There are various strategies and techniques used to design security systems. However there are few, if any, effective strategies to enhance security after design. One technique enforces the Link Removed due to 404 Error to great extent, where an entity has only the privileges that are needed for its function. That way even if an Link Removed due to 404 Error gains access to one part of the system, fine-grained security ensures that it is just as difficult for them to access the rest.
Furthermore, by breaking the system up into smaller components, the complexity of individual components is reduced, opening up the possibility of using techniques such as Link Removed due to 404 Error to prove the correctness of crucial software subsystems. This enables a Link Removed due to 404 Error to security that works well when only a single well-characterized property can be isolated as critical, and that property is also assessible to math. Not surprisingly, it is impractical for generalized correctness, which probably cannot even be defined, much less proven. Where formal correctness proofs are not possible, rigorous use of Link Removed due to 404 Error and Link Removed due to 404 Error represent a best-effort approach to make modules secure.
The design should use "Link Removed due to 404 Error", where more than one subsystem needs to be violated to compromise the integrity of the system and the information it holds. Defense in depth works when the breaching of one security measure does not provide a platform to facilitate subverting another. Also, the cascading principle acknowledges that several low hurdles does not make a high hurdle. So cascading several weak mechanisms does not provide the safety of a single stronger mechanism.
Subsystems should default to secure settings, and wherever possible should be designed to "fail secure" rather than "fail insecure" (see Link Removed due to 404 Error for the equivalent in safety engineering). Ideally, a secure system should require a deliberate, conscious, knowledgeable and free decision on the part of legitimate authorities in order to make it insecure.
In addition, security should not be an all or nothing issue. The designers and operators of systems should assume that security breaches are inevitable. Full Link Removed due to 404 Error should be kept of system activity, so that when a security breach occurs, the mechanism and extent of the breach can be determined. Storing audit trails remotely, where they can only be appended to, can keep intruders from covering their tracks. Finally, Link Removed due to 404 Error helps to ensure that when bugs are found the "Link Removed due to 404 Error" is kept as short as possible.
