A computer system consists of a set of hardware and software objects. The protection domain is a set of pairs of objects and rights needed to access those objects. An access matrix is a representation of protection domains. (It is more conceptual than actual however.) Each row specified the object, and a right that can be performed as…
User authentication is the act of verifying the identity of a person who wishes to connect to a computer or a network. This can be done in several ways, but most commonly is through a user name and password. For more complex, or sensitive systems, you may be asked to use two (or more) factor authentication….
Computer security is the freedom from theft of or damage to hardware, software, or information, and from disruption or misdirection of services. Protection is the set of mechanisms and policies that guarantee computer security, including the confidentiality, integrity, availability, and authenticity of all data and services. Common types of compromised computer security Information disclosure Information modification Information…
Two conditions must hold for a deadlock to occur with reusable resources: Hold and wait: A process is already holding one resource and is requesting another resource. Circular wait: A process must issue a resource request that closes a cycle involving at least two processes and two resources. Deadlock is structurally impossible if either of…
One approach to dealing with deadlocks is to allow deadlocks to occur and to provide means for detection and recovery. Recovery from a deadlock can be accomplished by destroying one or more of the processes involved in the deadlock, or by removing some of the resources held by the deadlocked processes. However, this causes a…
The Bubble Sort is one of the simplest sorts you can write, from a developer’s perspective. Unfortunately, it is one of the slowest to run from the computer’s perspective. A bubble sort works on the following idea. Given a list of values, start at the top value and look at the next value. If the…
Quickly finding and sorting data is a very important part for many developers as it allows users to search and find data quickly. While many languages have built in sorting algorithms, sometimes we only have a template that we need to finish. This is especially true for complex data types which aren’t as easy to…
If our data is pre-sorted then a binary search starts to make a lot of sense. It is like the guessing game we mentioned earlier where you need to find a number between 1 and 100. No one asks for 1, then 2, then 3… until they find it. Instead we ask for the mid…
