Complexity of Substitution Encryption and Decryption

An important issue in using any cryptosystem is the time it takes to turn plaintext into ciphertext, and vice versa. Especially in the field it is essential that the scrambling and unscrambling do not deter the authorized parties from completing their missions. The timing is directly related to the complexity of the encryption algorithm. For example encryption and decryption with substation ciphers can be performed by direct lookup in a table illustrating the correspondence, like the ones shown in example. One way thinking of this expression is that if one message is twice as long as another, it will take twice as long to encrypt.

Substitution Ciphers of Computing System

Children sometimes devise ‘secret codes’ that use a correspondence table with which to substitute a character or symbol for each character of the original message. This technique is called a monoalphabetic cipher or simple substitution, A substitution is an acceptance way of encryption text. Read More

Cryptanalysis in security system

A cryptanalysts chore is to break an encryption. That is the cryptanalyst attempts to m, deduce the original meaning of a ciphertext message. Better yet, he or she hopes to determine which decrypting algorithm matches the encrypting algorithm, so that other message encoded in the same way can be broken. Thus a cryptanalyst can do any or all of six different things-

Attempt to break a single message

Attempt to recognize patterns in encrypted messages, to be able to break subsequent ones by applying a straightforward decryption algorithm

Attempt to infer some meaning without even breaking the encryption, such as noticing an unusual frequency of communication or determining something by whether the communication was short or long.

Attempt to deduce the key in order to break subsequent message easily

Attempt to find weaknesses in the implementation or environment of use of encryption.

Terminology process

Encryption is the process of encoding a message so that its meaning is not obvious. Decryption is the reverse process, transforming an encrypted message back into its normal, original form. Alternatively the terms encode and decode or encipher and decipher are used instead of encrypt and decrypt. That is we say that we encode encrypt or encipher the original message to hide its meaning. Then we decode, decrypt or decipher it to reveal the original message. A system for encryption and decryption is called a cryptosystem.

The original form of a message is known as plaintext, and the encrypted form is called cipher text. For convenience in explanation, we denote a plaintext message p as a sequence of individual characters p={p1, p2, …..pn}. Similarly cipher text is written as C={c1, c2,…..cm}. for instance, the plaintext message “ I want cookies” can be through  of as the message string { I, w ,a, n, t, c, o, o, k, I, e, s}. it may be transformed into cipher text { c1, c2, ……c14} and the encryption algorithm tells us how the transformation is done.            

Controls in security system

To consider the controls or countermeasures that attempts to prevent exploiting computing system vulnerabilities, we begin by thinking about traditional ways to enhance physical security. In the middle ages, castles and fortresses were built to protect the valuable people and property inside. The fortress might have had one or more security characteristics including-

• A strong gate or door to repel invaders
• Heavy walls to withstand objects thrown or projected against them
• A surrounding moat, to control access
• Arrow slits to let archers shoot at approaching enemies

   Read More 

Career Criminals

By contrast the career computer criminal understands the targets of computer crime. Criminals seldom change fields from arson or auto theft to computing more often criminals begin as computer professionals who engage in computer crime finding the prospects and payoff good. There is some evidence that organized crime and international groups are engaging in computer crime. Recently electronic spies and information brokers have begun to recognize that trading in companies or individuals secrets can be lucrative. 

What is Amateurs?

Amateurs have committed most of the computer crimes reported to date. Most embezzlers are not career criminals but rather are normal who observe a weakness in a y security system that allows them to access cash or other valuables. In the same sense computer criminals are ordinary computer professionals or users doing their jobs, when they discover they have access to something valuable. When no one objects the amateur may start using the computer at work to write letters maintain soccer league team standings or do accounting.  

Difference between VBScript and Java script

Java Script:

1.      Java script case sensitive

2.      Java Script will be run on client side.

3.      JavaScript will explore in all the browser

4.      JavaScript is  more like c++

5.      JavaScript is client side validation

Example: Var x;

             for(x=1;x<=10;x++)

            {

            document.write(x+”<BR>”);

           }

BV Script:

1.      VBScript not case sensitive

2.      VBScript both client  side and server side

3.      VBScript is like VB

4.      VB accept only internet explore

5.      VBScript for server side validation

   Example:
Dim x
For x=1 to 10
Document. Write x & “<BR>”
next

Fully integrated EDI and Financial EDI

Fully Integrated EDI:
Fully integrated EDI systems encompass electronic data sharing throughout all aspects of the purchasing and payments cycle. The fully integrated EDI system allows the purchasers computer system to electronically check inventory levels and production schedules to determine whether the requested item in stock or when it scheduled to be produced. 

Financial EDI: 
The banker EDI council defines financial EDI as the electronic exchange of payments related information or financially related documents in standard formats between partners. Financially EDI is the key distinguishing feature between partially and fully integrated EDI systems. Some farms may transfer funds electronically and produce the remittance advice in hard copy format that is sent through the postal service.

Internet Technology Clint / Server Application

In a client/ server application there are two major classes of Software:

Client Software:

Client Software usually residing on an end users desktop and providing navigation and display.

Server Software:

Server Software usually residing on a workstation or server class machine and providing backend data access services( where the data can be something simple like file or complex like a relational database). As an example: E-mail- the protocol is simple mail transport protocol and its purpose is allows the transmission of text message and binary attachments across the internet technology.  Another one is Chat and its protocol name is internet relay chat protocol, it provides away by one user to talk to one another in real time over the internet. The real time chat groups are called channels.