add script and info for RSA encrypt/decrypt

.gitignore

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+# Byte-compiled / optimized / DLL files
+__pycache__/
+*.py[cod]
+*$py.class
+encrypted_file.txt
+
+# C extensions
+*.so
+
+# Distribution / packaging
+.Python
+build/
+develop-eggs/
+dist/
+downloads/
+eggs/
+.eggs/
+lib/
+lib64/
+parts/
+sdist/
+var/
+wheels/
+share/python-wheels/
+*.egg-info/
+.installed.cfg
+*.egg
+MANIFEST
+
+# PyInstaller
+#  Usually these files are written by a python script from a template
+#  before PyInstaller builds the exe, so as to inject date/other infos into it.
+*.manifest
+*.spec
+
+# Installer logs
+pip-log.txt
+pip-delete-this-directory.txt
+
+# Unit test / coverage reports
+htmlcov/
+.tox/
+.nox/
+.coverage
+.coverage.*
+.cache
+nosetests.xml
+coverage.xml
+*.cover
+.hypothesis/
+.pytest_cache/
+
+# Translations
+*.mo
+*.pot
+
+# Django stuff:
+*.log
+local_settings.py
+db.sqlite3
+
+# Flask stuff:
+instance/
+.webassets-cache
+
+# Scrapy stuff:
+.scrapy
+
+# Sphinx documentation
+docs/_build/
+
+# PyBuilder
+target/
+
+# Jupyter Notebook
+.ipynb_checkpoints
+
+# IPython
+profile_default/
+ipython_config.py
+
+# pyenv
+.python-version
+
+# celery beat schedule file
+celerybeat-schedule
+
+# SageMath parsed files
+*.sage.py
+
+# Environments
+.env
+.venv
+env/
+venv/
+ENV/
+env.bak/
+venv.bak/
+
+# Spyder project settings
+.spyderproject
+.spyproject
+
+# Rope project settings
+.ropeproject
+
+# mkdocs documentation
+/site
+
+# mypy
+.mypy_cache/
+.dmypy.json
+dmypy.json
+
+# Pyre type checker
+.pyre/
+
+# PyCharm specific
+.idea
+ 

LICENSE

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+MIT License
+
+Copyright (c) 2021 Vicky Rampin
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

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+# 2021 CSCI-GA3205 Homework 11
+Author: Vicky Rampin
+
+## Prompt
+Write a program to encrypt and decrypt a message (string) using the RSA algorithm. You can implement the functions you need or use the libraries.
+
+## Installation
+This script is made with Python 3.8 and uses the `argparse` and `pycryptodome` libraries. Ensure that you have [Python 3.8+](https://www.python.org/downloads/) and these libraries installed in order to run this script correctly.
+
+## Usage
+First, clone this repository to your machine. Open the command line on your machine and navigate to where you cloned this repository. To get help using `cd`, use [this tutorial](https://swcarpentry.github.io/shell-novice/02-filedir/index.html).
+
+Before running the script, you should know it expects one argument:
+1. `--msg`: provide a message that you want to encrypt and decrypt
+
+With this in mind, you can run it like so:
+
+```
+$ python index.py --msg="helloWORLD"
+```
+
+It will encrypt and decrypt the message using a randomly generated public and private key pair (RSA), and print as it goes.

index.py

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+import argparse
+from Crypto.Cipher import PKCS1_OAEP
+from Crypto.PublicKey import RSA
+
+
+def encrypt(text, pub):
+    public_key = RSA.importKey(pub)
+    public_key = PKCS1_OAEP.new(public_key)
+    encrypted_msg = public_key.encrypt(text)
+    return encrypted_msg
+
+
+def decrypt(text, priv):
+    private_key = RSA.importKey(priv)
+    private_key = PKCS1_OAEP.new(private_key)
+    decrypted_msg = private_key.decrypt(text)
+    return decrypted_msg
+
+
+def main():
+    # get arguments from command line
+    parser = argparse.ArgumentParser()
+    parser.add_argument('--msg', type=str)
+    args = parser.parse_args()
+
+    # generate public and private keys to use for encryption and decryption
+    key = RSA.generate(3072)
+    priv = key.export_key('PEM')
+    pub = key.publickey().exportKey('PEM')
+
+    # print original message
+    original = args.msg
+    print("Original message: " + original)
+
+    # print encrypted message
+    ciphertext = encrypt(original.encode(), pub)
+    print("Encrypted message: ")
+    print(ciphertext)
+
+    # print decrypted message
+    plaintext = decrypt(ciphertext, priv)
+    print("Decrypted message: " + plaintext.decode())
+
+
+if __name__ == '__main__':
+    main()