Cryptography, Computer Engineering

Basically I need implement program using LC3 assembly language where I can type any message using ASCII code (this will my input). Then read the output in cipher text. It has to be a combination of this to labs in the bottom. ( please make sure design the flow chart for the program)

Computer Organization and Architecture Lab 4: Cryptography

Description:

An encryption algorithm transforms "plain text" into "cipher text." Just like a door needs a key to lock and unlock it, an encryption algorithm often requires a key to encrypt and decrypt a message. For example, suppose the plain text message is HELLO WORLD. An encryption algorithm consisting of nothing more than replacing each letter with the next letter in the alphabet would produce the cipher text IFMMP XPSME. The decryption algorithm simply replaces each letter with the one before it, and presto: the plain text HELLO WORLD is produced.
Procedure:

Implement, in LC-3 assembly language, an encryption/decryption program that meets the following requirements:
1. The key is 6 and stored at x31 00.
2. Your message is restricted to a maximum of 32 characters. They are stored at x3110 to x311 F. The last ASCII code of the text string must be EOT (x04).
3. The encryption algorithm is as follows. Each ASCII code in the message will be transformed as follows:
• The low order bit (LSB) of the code will be toggled. That is, if it is a 1, it will be replaced by 0 and vice verse.
• The key will be added to the result of step 1 above.
• The result should be stored at location x3120 to x312F.
• For example, if the input (plain text) is A and the encryption key is 6, the program should take the ASCII value of A, 01000001, toggle bit [3:0], producing 01001110 and then add the encryption key, 6. The final output character would be 01000110, which is the ASCII value F.
4. Decryption algorithm is as follows. Each ASCII code in the message will be transformed as follows:
• Subtract the encryption key from the ASCII code.
• Toggle the low order bit of the result of ste

• The result should be stored back to location x311 0 to x311 F.
Notes and Suggestions:
• The first line of your programs must specify the memory address of the first instruction of your program. LC-3 simulator will place your program starting at that address. For this assignment, you should place your program starting at x3000 (using the .ORIG pseudo¬op) .
• If you are using a Windows machine, use the LC3Edit program to type in your programs.
On Sun and Linux workstations, pico, emacs, and vi are several of the text editors you can use. Your program file needs to be in plain text format.

Posted Date: 2/22/2013 6:42:19 AM | Location : United States







Related Discussions:- Cryptography, Assignment Help, Ask Question on Cryptography, Get Answer, Expert's Help, Cryptography Discussions

Write discussion on Cryptography
Your posts are moderated
Related Questions
advantages of sdr

Define Edge-triggered S-R flip-flop Basic Symbol small triangle, called the dynamic input indicator, is used to identify an edge-triggered flip-flop. Truth Table.

Image Capturing Download the following grey level 512x512 standard images in TIF format: a-Lena       b-Baboon     c-Bridge       d-Airfield Use Matlab to decrease the siz

Calculate the number of trunks that can be supported on a time multiplexed space switch given that, 32 channels are multiplexed in each stream, while the control memory access time

All digital devices are made from circuits whichcan be switched between two possible states.These two states are represented by a voltagelevel at the output of the circuit e.g. 0V

What are the components of I-way Infrastructure? There are three components of the I-way infrastructure: • Consumer access equipment • Local on-Ramps • Global informat

Two Layer Artificial Neural Networks: However decision trees are whenever powerful they are as a simple representation scheme. Whereas graphical on the surface that they can b

What do you mean by u-area (user area) or u-block? This having the private data that is manipulated only by the Kernel. This is local to the Process, i.e. every process is a

Why disable statements are not allowed in functions? If  disble  statement  is used  in function,it  invalids  function  and  its  return  value.  So  disable statements aren't

Question: (a) Program instructions and data are brought into memory first, in order to be executed. Explain how the CPU enables an instruction to be executed? (b) Describe