Ecryption/Decryption REST Service

aes.py

#!/usr/bin/python
# -*- coding: utf-8 -*-

"""
    Ecryption/Decryption REST Service
    =================================

    INSTALLATION
    ------------

        python -m venv .venv
        source .venv/bin/activate
        pip install flask pycryptodome pytest

    DEPLOY
    ------

        FLASK_APP=aes.py flask run

    USAGE
    -----

        curl -X POST http://localhost:5000/decrypt -d'encrypted=/gqxzcVtRUlw4nzSETa40dAIq4lOdonshBBjtQfY3ewicIKMwKIllXVZldsTPCGH'

"""

import base64
import hashlib

from Crypto import Random
from Crypto.Cipher import AES

from flask import Flask
from flask import request


class AESCipher(object):
    """
    AES Cipher tool for conveniently handling CBC mode.

    Inspired by https://stackoverflow.com/a/21928790/2235622
    """
    def __init__(self, key):
        self.bs = 16
        self.key = hashlib.sha256(key.encode()).digest()

    def encrypt(self, raw):
        raw = self._pad(raw)
        iv = Random.new().read(AES.block_size)
        cipher = AES.new(self.key, AES.MODE_CBC, iv)
        return base64.b64encode(iv + cipher.encrypt(raw.encode('utf-8')))

    def decrypt(self, enc):
        enc = base64.b64decode(enc)
        iv = enc[:AES.block_size]
        cipher = AES.new(self.key, AES.MODE_CBC, iv)
        return self._unpad(cipher.decrypt(enc[AES.block_size:])).decode('utf-8')

    def _pad(self, s):
        return s + (self.bs - len(s) % self.bs) * chr(self.bs - len(s) % self.bs)

    @staticmethod
    def _unpad(s):
        return s[:-ord(s[len(s) - 1:])]


def test_aes_roundtrip():
    """ Test Harness """
    cipher = AESCipher('thisisunsafe--changeit!')
    to_encrypt = 'MeinSuperGeheimesPasswort1337!'
    encrypted = cipher.encrypt(to_encrypt)
    print(encrypted)
    decrypted = cipher.decrypt(encrypted)
    assert to_encrypt == decrypted


"""
Start Web Service
"""

app = Flask(__name__)
cipher = AESCipher('thisisunsafe--changeit!')


@app.route("/decrypt/<to_decrypt>")
def decrypt(to_decrypt):
    return cipher.decrypt(to_decrypt)


@app.route("/decrypt", methods=['POST'])
def decrypt_post():
    return cipher.decrypt(request.form['encrypted'])


@app.route("/encrypt/<to_encrypt>")
def encrypt(to_encrypt):
    return cipher.encrypt(to_encrypt)