Rotor Machine Cipher

Rotor Machine cipher is a substitution cipher which falls under the subcategory of polyalphabetic substitution ciphers.

What is a rotor machine?
Rotor machine is an electro-mechanical equipment used to encrypt and decrypt plaintext to ciphertext in cryptography which was widely used in the 1930s-1950s. One of the most common implementation of rotor machine is Enigma machine which is shown below.

How Rotor Machines Operate
Recommended reference to understand the operation of rotor machine is given below.
http://www.cleavebooks.co.uk/trol/trolc07.pdf

Computer Security and Availability

Computer security is preventing and detecting unauthorized use of your system. It is said that the system which doesn’t allow any users to access its data and functions, has the highest security. In other hand more and more features and high performance will result in less secure systems. But such systems with no access, no performance and minimal features are simply useless in modern days. So we have to clearly balance between security and availability.
And another important fact about computer security in a enterprise is that the decisions regarding security ultimately should be driven by business requirements, not security requirements. Security requirements should be dictated by the business need, not the other way around.
A good article to refer about how to balance security and availability that I recommend is given below.
http://www.continuitycentral.com/feature0362.htm
Another good article for security for small business organizations is given below,
http://www.corpcomputerservices.com/network-security.php