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Detective RSA

In this assignment, you will use RSA functions to discover the secret behind the mysterious sus.txt and rev.txt files.

The content of the file sus.txt is encrypted using a public key. Your task is to find the correct private key out of 20 possible keys in the key_pairs directory to decrypt that message. The starter code is in rsa.py. Complete it and submit only rsa.py to Gradescope.

Options to implement

a. Generate public and private keys 
b. Find the right key and decrypt the message in sus.txt 
c. Sign a message and verify it 
d. Find Miss Reveille's key pair that she used to sign rev.txt 
q. Quit

a. Generate a public/private key pair, encrypt, and decrypt

  1. Generate a public/private key pair using 2048 bits key length using the function generate_keys(). Save the public and private keys in two files.
  2. Encrypt a plaintext using the function encrypt_message().
  3. Decrypt a cyphertext using the function decrypt_message().

b. Find the right key and decrypt the message in sus.txt

  1. Write the function find_decrypt_key(), to find which key in the key_pairs directory can decrypt the sus.txt message.
  2. Once you find the right key, decrypt the file sus.txt.
  3. Write the decrypted message in the file sus_decrypted.txt. Note: You should realize it was written by Miss Rev.
  4. Your next task is to find Miss Rev's signature key in the key_pairs directory. This is not the same key as the one used in part b.

c. Sign a message using the private key from part a.1 and verify the signature

Write the functions sign_message() and verify_message() to sign and verify a message, respectively.

  1. Sign a message using the private key from part a.1.
  2. Write the signature in a file signed_msg.txt.
  3. Verify the signature using the public key from part a.1.

d. Identify the real Reveille's signature

Find the correct Reveille's signature by verifying the signature of the message in sus_decrypted.txt. Use a method similar to part b to find which key is used to sign the messagerev.txt.

PyCryptodome

We need pycryptodome to run this program. If not installed, to install pycryptodome in Python 3, type:

make install

or

python3 -m pip install pycryptodome

Usage

To run the program, type:

make run

To clean up the files generated by the program, type:

make clean

Important notes:

  1. A small starter video here: https://youtu.be/4Le42qqSZeA
  2. You only need read(r) and write(w) access to the files. Use the b flag when opening the files along with r and w. Read more at: https://www.programiz.com/python-programming/methods/built-in/open
  3. In the key_pairs directory, the public key suffix is _pub, and the private key suffix is _priv.
  4. Your program will be manually tested for correctness with additional test cases.
  5. Your program should execute with no errors and warnings.