It is an assembly language labVigenere cipher MIPS Mars

Lab Overview:

You will be implementing the Vigenere cipher ( see https://en.wikipedia.org/wiki/Vigen%C3%A8re_cipher ) to encrypt and decrypt strings provided as the program arguments.

There are two required functions for this lab as shown below:

encode(address of cipher key, address of clear text, address of cipher text): Takes in the addresses of 2 properly terminated strings and the address of memory for output. It will encode the clear text using the given key and store it in the cipher text memory. Be sure to properly terminate the output string.

decode(address of cipher key, address of cipher, text address of clear text): Takes in the addresses of 2 properly terminated strings and the address of memory for output. It will decode the cipher text using the given key and store it in the clear text memory. Be sure to properly terminate the output string.

Neither of these functions perform input or output, this will be the responsibility of your main code.

Instead of providing a flow chart for the code, we are instead providing the source code in C. The code contained in cipher.c is fully functional except that it does not use program arguments for brevity. Match its output format. Do not use a C compiler to write the code.

Program Flow:

Outside of the functions your code has a few requirements.

Use the program arguments to determine both the key and the clear text. The key will be the first string while the second will be the clear text.

Print out the given clear text and the key.

Encode using the encode function and print out the encoded version.

Decode using the decode function and print out the decoded version. They should match and

you may not print out the input text again.

For ease of use we are limiting the length of the clear text to 100 characters. Part of your data segment should include declarations for both the encoded and decoded versions of your string. Assume sane input and do not attempt to correct invalid input.

Program Arguments:

As in lab 3 we are using program arguments as input to your program. Unlike lab 3 we will not be providing you the code that handled them for you.

Arguments to your program are stored as strings, you saw this when you had to convert the decimal number to binary. Strings are separated by spaces unless enclosed by double quotes.

In this case we have four program arguments: A, quick, brown fox and jumped. We use a0 and a1 to interface with the program arguments in the following manner:

a0 (argc): This is an integer value telling us how many program arguments have been received. This value can be used to iterate over all the submitted strings.

a1 (argv): This is an array of memory addresses to strings. Loading a1[0] for example would return the address where A is stored while a1[1] would return the address to quick. Each string is null terminated.

For the purposes of this program you will need to use the first two elements of the array.

Sample Output: For full credit you must match the output format. The output below is from three separate runs of the program The given key is: Latin The given text is: repetitio est mater studiorum The encrypted text is FdNb5U]X1Th[-UY[?UiMW; siv The decrypted text is: repetitio est mater studiorum The given key is: ABC The given text is: abcdefghijklmnopqrstuvwxyz The encrypted text is: "S&%') (*,+-/.0213546879;:t