The Storyboard stage

Mention what will be your animation medium: 2D or 3DMention the software to be used for animation development: JAVA, Flash, Blender, Shikav, Maya..etc

Medium : 3D

Software to be used for animation development: Blender

Title of the concept, subject. Name of the author

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Title of the concept : Rotor Machine

Subject : Cryptography

Name of Author : Kadambari Devarajan

Definitions of the keywords used in the animation 2

Encryption : In cryptography, encryption is the process of transforming information (referred to as plaintext) using an algorithm (called cipher) to make it unreadable to anyone except those possessing special knowledge, usually referred to as a key. The result of the process is encrypted information (in cryptography, referred to as ciphertext).

Decryption : The reverse process of Encryption that is used to make the encrypted information readable again is called Decryption.

Cipher : In cryptography, a cipher (or cypher) is an algorithm for performing encryption or decryption.

Rotor Machine : This is an electromechanical device used for encrypting and decrypting messages.The machine consists of a set of independently rotating cylinders through which electrical pulses can flow.

Describe the concept chosen and clearly illustrate how you want to explain the concept in the animation.

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* The rotor machine is worth animating, since it offers great scope to explain ciphers, encryption, decryption, and provide an introduction to cryptography, along with a historical perspective using examples of existing rotor machines.

* This would be a visual aid in understanding complex, polyalphabetic subsititution ciphers in general cryptography, apart from help understand related concepts of encryption, decryption, types of ciphers, etc. This could be done in 2D as well, but 3D would be apt as each stage of the transformation can be understood clearly this way, as would the step-by-step process of how encryption here works.

* A Rotor Machine is an electro-mechanical device used for encrypting and decrypting secret messages. It contains a set of rotating discs, with an array of electrical contacts, called 'rotors'. A complex scrambling of the input if done using a fixed subsititution of letters implemented by means of the wiring in the electrcial contacts. The security of this is ensured since after encrypting each letter, the rotor advances positions and thereby changing the substitution.

Problem Statement :Describe examples/experiments/analogies through which you will explain (use bullets).

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Problem Statement : The concept of a rotor machine is to be implemented in the form of an animation to explain the tenets of the use of ciphers in cryptography.Examples : Existing rotor machines such as the 'Enigma Machine' and types of ciphers, use of ciphers etc.in networks and other applicationsExperiments : Exercises involving enciphering and deciphering text based on classical ciphers.Analogies : Real-world applications of cryptography, ciphers etc., analogies involving famous ciphers.

Problem statement: Stepwise description and illustrations (Add more slides if necessary)

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* The machine consists of a set of independently rotating cylinders through which electrical pulses can flow.

* Each cylinder has 'n' input pins and 'n' output pins, with internal wiring that connects each input pin to a unique output pin, where each input and output pin can be associated with a letter of the alphabet.

* If the key for letter A is depressed, an electric signal is applied to the first pin in the first cylinder and flows through the internal connection to the (n-1)th output pin.

* After each input key is depressed, the cylinder rotates one position, so that the internal connections are shifted accordingly. After 'n' letters of plaintext, the cylinder would be back to the initial position. Thus, we have a polyalphabetic substitution algorithm with a period of 'n'.

* Use multiple cylinders wherein the output pins of one cylinder are connected to the input pins of the next. With multiple cylinders, the one closest to the operator input rotates one pin position with each keystroke. Suppose it is a three cylinder system, for every complete rotation of the innercylinder, the middle cylinder rotates one pin position. And, for every complete rotation of the middle cylinder, the outer cylinder rotates one pin position.

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Weaknesses in Rotor Machines of use during interception: First, a letter can never be encrypted to itself. This property is of great help in using 'cribs'—short sections of plaintext thought to be somewhere in the ciphertext—and could be used to eliminate a crib in a particular position. For a possible location, if any letter in the crib matched a letter in the ciphertext at the same position, the location could be ruled out.

A second Enigma weakness was that the plugboard connections were reciprocal, so that if A was plugged to N, then N likewise became A. Similarly, for some networks, the rules forbid a letter being connected to an adjacent one on the alphabet.

Some devices such as the 'Cyclometer', 'Zygalski's Perforated Sheets', distributed computing, 'bomba kryptologiczna' or the Cryptologic Bomb and the British and American Bombe, can also be used for decryption. Even complex frequency analysis techniques would rarely be successful.

List out user interactions that will be there to enhance the understanding of the concept in the animation.

* The user can try varying the input given to the Rotor Machine and understand how encryption works using this mechanism. * Another possible user interaction is to actually let the user design his/her own rotor machine by specifying number of cylinders, inputs etc. This will involve additional work and can be considered an extension of this animation, or simulated separately.

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A small questionnaire with answers based on the concept.

Q1. Is the rotor machine an effective tool for encrypting and decrypting secret messages?A1. Yes.

Q2. How does the rotor machine ensure continuous secure encryption?A2. By advancing postions after each letter, i.e.changing subsitution.

Q3. How can the complexity of encryption be increased?A3. By increasing the number of rotors / cylinders.

Q4. Can the complexity of the system be varied?A4. Yes, my many means.

Q5. Can rotor machines be applied in other domains?A5. Yes. For example, Image Processing and networks, among others.

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Links for further reading/references 9

1. http://en.wikipedia.org/wiki/Rotor_machine

2. http://www.jproc.ca/crypto/

3. http://users.telenet.be/d.rijmenants/en/timeline.htm

4. http://en.wikipedia.org/wiki/Enigma_machine

5. http://users.telenet.be/d.rijmenants/en/faq.htm

6. Cryptography and Network Security : Principles and Practice, by William Stallings