PROGRAM THRASHED

PROGRAM THRASHED
*Trojan Horse:-
Many system have mechanism for allowed programs, written by users to be executed by other user. If these programs are executed in a domain that provides the access nights of the executing user. The other user may be misused these nights. A text editor program, for example may include forced to the search the file to be edit for certain keywords if any are formed the entire file may be copied to a special area access by to the creator of a text editor. A code segment that misused in environment is called a Trojan Horse.

*Trap Door:-
The designer of a program or system mind leaved a code in the software that only she/he is capable of using this type of security be reach as trap door was showed in the movie/war game. The code might check for the specific user ID or password, it might normal security procedure. This accounting crediting can add up to a large amount of many considering the number of transaction  that a large bank executes.
 A flavor trap door could be included in a compiler. The compiler could generate standard object code as well as a trap door regardness of the source code being compile.
Trap Door pose a difficult problem because to detect them we have to analyses all the source code for all components of a system given that software system may consist of millions of line of code. This analysis is not done frequently and frequently is not done at all.

*Virus:-

Another form of program threat is a virus. Viruses are self-replicating and are designed to infect another program. A virus is a fragment of code as with most viruses are very specific to architecture OS and application. Viruses are a particular problem for user of personal computer.  
Viruses are usually born via email. They can also spread users download programs from internet files sharing services or exchanged inflected disk. Another common form of virus transmission uses Microsoft office file such as  Microsoft word documents.
These document can certain macros (visual basic program) that programs in the office suit(word, power-point, excel) will execute automatically.

*Encryption:-
Encryption is means for constructing the possible receivers of a message because it solve a wide variety of communication sequrity problem. Encryption is used frequently in many aspects of modern computing.
An Encryption algorithm enables the sender of a message to ensure that only a computer processing a certain key can read the memory.
Example:-Two users communicating securely over an insecure channel. We refer to this figure throughout the section, note that key exchange can take place directly between the two parties or via a trusted third party that is a certificate authority.

*Spooling:-
A pool is a buffer that codes output for a device such as a printer that can't accept data string although a printer can search only one job at a time. Several's application may wish to point their output concurrently without having them output mixed together. The OS solved the problem by intercepting all output is spooled to a separate disk file when an application finished printing the spooling system queue  the corresponding spool file for output to the computer. The spooling system copies the queued spool file to the printer at one time. In some OS spooling is managed by a system process. The OS provides a control interface that enables users ans system administrators to display the queue, remove unwanted job before these job point. Suspended print while the printer is serviced and so on.