Building

Run the following command to build the program:

make

Execution

Run the following command to encrypt plaintext1.txt with key1.txt:

 ./a3-program plaintext1.txt key1.txt

Testing

A quick way to test is by running:

make test

which builds, and runs the program with the plaintext set to test/test1plaintext.txt and the key set to test/test1key.txt.

The key files:

• test1key.txt
• test2key.txt
• test3key.txt

Along with the plain-text files:

• test1plaintext.txt
• test2plaintext.txt
• test3plaintext.txt

are provided for testing purposes.

Expectations

At a mininum, you should implement separates routines to perform the following operations (I’m using the names from the FIPS document):

• SubBytes(), InvSubBytes() that performs the s-box substitutions.
• KeyExpansion() that expands the input key into the 11 round keys.
• ShiftRows(), InvShiftRows() that shifts the rows.
• MixColumns(), InvMixColumns() that does the matrix multiplication in GF(256).

You should also have a routines for the encryption and decryption algorithms (encrypt(), decrypt()). Please use the names provided above to make your code easier to read and grade.