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Encryption: From PyCrypto to CryptoJS
Raw
README.md

Encryption: From PyCrypto to CryptoJS

Sample code to encrypt using Python and decrypt in Javascript

Raw
app.js
var encrypted;
// Send the #to_encrypt string to be encrypted by Python and populate the Encryption Result Section
$("#do_encrypt").click(function () {
var post_data = {
to_encrypt: $("#to_encrypt").val()
};
$.post("/encrypt", post_data, function (data) {
encrypted = data;
$("#encrypt_key").val(data.key);
$("#encrypt_iv").val(data.iv);
$("#encrypt_ct").val(data.ciphertext);
$("#do_decrypt").removeAttr("disabled");
});
});
// Output the decryption result to #decrypted, based on encrypted data from #do_encrypt
$("#do_decrypt").click(function () {
var key = CryptoJS.enc.Hex.parse(encrypted.key),
iv = CryptoJS.enc.Hex.parse(encrypted.iv),
cipher = CryptoJS.lib.CipherParams.create({
ciphertext: CryptoJS.enc.Base64.parse(encrypted.ciphertext)
}),
result = CryptoJS.AES.decrypt(cipher, key, {iv: iv, mode: CryptoJS.mode.CFB});
$('#decrypted').val(result.toString(CryptoJS.enc.Utf8));
});
Raw
index.html
<html>
<head>
<title>Encryption: from Python to JS</title>
<link rel="stylesheet" href="//netdna.bootstrapcdn.com/bootstrap/3.0.3/css/bootstrap.min.css" type="text/css" />
<script src="//ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js"></script>
</head>
<body>
<div class="container">
<h1>Encryption: from Python to JS</h1>
<!-- To Encrypt Section -->
<div class="panel panel-default">
<div class="panel-body">
<div class="form-group">
<label for="to_encrypt">To encrypt:</label>
<textarea id="to_encrypt" class="form-control">A very secret statement made by an import person.</textarea>
</div>
<button id="do_encrypt" type="button" class="btn btn-primary">Encrypt Using Python</button>
</div>
</div>
<!-- Encrypted Result Section -->
<div class="panel panel-default">
<div class="panel-body">
<label>Encryption Result:</label>
<div class="form-horizontal">
<div class="form-group">
<label for="encrypt_key" class="col-sm-2 control-label">Key:</label>
<div class="col-sm-10">
<input id="encrypt_key" class="form-control" disabled>
</div>
</div>
<div class="form-group">
<label for="encrypt_iv" class="col-sm-2 control-label">IV:</label>
<div class="col-sm-10">
<input id="encrypt_iv" class="form-control" disabled>
</div>
</div>
<div class="form-group">
<label for="encrypt_ct" class="col-sm-2 control-label">Encrypted:</label>
<div class="col-sm-10">
<textarea id="encrypt_ct" class="form-control" disabled></textarea>
</div>
</div>
</div>
</div>
</div>
<!-- Decrypt Section -->
<div class="panel panel-default">
<div class="panel-body">
<div class="form-group">
<label for="decrypted">Decrypt:</label>
<textarea id="decrypted" class="form-control"></textarea>
</div>
<button id="do_decrypt" type="button" class="btn btn-primary" disabled>Decrypt Using JS</button>
</div>
</div>
</div>
<script src="//crypto-js.googlecode.com/svn/tags/3.1.2/build/rollups/aes.js"></script>
<script src="//crypto-js.googlecode.com/svn/tags/3.1.2/build/components/mode-cfb.js"></script>
<script src="app.js"></script>
</body>
</html>
Raw
server.py
#!/usr/bin/env python
import os, json
import binascii
from cgi import parse_header, parse_multipart
from urlparse import parse_qs
from BaseHTTPServer import BaseHTTPRequestHandler, HTTPServer
from Crypto import Random
from Crypto.Cipher import AES
# ------------------------------
# DEFINE Encryption Class
class Cryptor(object):
'''
Provide encryption and decryption function that works with crypto-js.
https://code.google.com/p/crypto-js/
Padding implemented as per RFC 2315: PKCS#7 page 21
http://www.ietf.org/rfc/rfc2315.txt
The key to make pycrypto work with crypto-js are:
1. Use MODE_CFB. For some reason, crypto-js decrypted result from MODE_CBC
gets truncated
2. Use Pkcs7 padding as per RFC 2315, the default padding used by CryptoJS
3. On the JS side, make sure to wrap ciphertext with CryptoJS.lib.CipherParams.create()
'''
# AES-256 key (32 bytes)
KEY = "01ab38d5e05c92aa098921d9d4626107133c7e2ab0e4849558921ebcc242bcb0"
BLOCK_SIZE = 16
@classmethod
def _pad_string(cls, in_string):
'''Pad an input string according to PKCS#7'''
in_len = len(in_string)
pad_size = cls.BLOCK_SIZE - (in_len % cls.BLOCK_SIZE)
return in_string.ljust(in_len + pad_size, chr(pad_size))
@classmethod
def _unpad_string(cls, in_string):
'''Remove the PKCS#7 padding from a text string'''
in_len = len(in_string)
pad_size = ord(in_string[-1])
if pad_size > cls.BLOCK_SIZE:
raise ValueError('Input is not padded or padding is corrupt')
return in_string[:in_len - pad_size]
@classmethod
def generate_iv(cls, size=16):
return Random.get_random_bytes(size)
@classmethod
def encrypt(cls, in_string, in_key, in_iv=None):
'''
Return encrypted string.
@in_string: Simple str to be encrypted
@key: hexified key
@iv: hexified iv
'''
key = binascii.a2b_hex(in_key)
if in_iv is None:
iv = cls.generate_iv()
in_iv = binascii.b2a_hex(iv)
else:
iv = binascii.a2b_hex(in_iv)
aes = AES.new(key, AES.MODE_CFB, iv, segment_size=128)
return in_iv, aes.encrypt(cls._pad_string(in_string))
@classmethod
def decrypt(cls, in_encrypted, in_key, in_iv):
'''
Return encrypted string.
@in_encrypted: Base64 encoded
@key: hexified key
@iv: hexified iv
'''
key = binascii.a2b_hex(in_key)
iv = binascii.a2b_hex(in_iv)
aes = AES.new(key, AES.MODE_CFB, iv, segment_size=128)
decrypted = aes.decrypt(binascii.a2b_base64(in_encrypted).rstrip())
return cls._unpad_string(decrypted)
# ------------------------------
# DEFINE HTTP Handler
class EncryptHandler(BaseHTTPRequestHandler):
'''
Simple webserver that server index.html and static "*.html" and "*.js" files,
which special "/encrypt" URL that would return a JSON with encrypted data
'''
PORT_NUMBER = 8087
SCRIPT_PATH = os.path.dirname(__file__)
def _return_http_code(self, http_code):
self.send_response(http_code)
self.end_headers()
def _return_file(self, in_file):
''' '''
if os.path.exists(in_file):
with open(in_file) as f:
self.send_response(200)
if in_file.endswith(".html"):
self.send_header('Content-type',"text/html")
elif in_file.endswith(".js"):
self.send_header('Content-type',"text/javascript")
else:
self.send_header('Content-type',"text/plain")
self.end_headers()
self.wfile.write(f.read())
else:
self._return_http_code(404)
def _return_json(self, in_dict):
'''Send JSON back to client from a dictionary'''
self.send_response(200)
self.send_header('Content-type','application/json')
self.end_headers()
self.wfile.write(json.dumps(in_dict))
def do_GET(self):
'''
Serve static .html and .js files
'''
request_path = self.path
if request_path == "/":
self._return_file("index.html")
elif request_path.endswith(".html") or request_path.endswith(".js"):
self._return_file(self.SCRIPT_PATH + request_path)
else:
self._return_http_code(404)
return
def parse_POST(self):
'''
parse POST body
'''
ctype, pdict = parse_header(self.headers.getheader('content-type'))
if ctype == 'multipart/form-data':
postvars = parse_multipart(self.rfile, pdict)
elif ctype == 'application/x-www-form-urlencoded':
length = int(self.headers.getheader('content-length'))
postvars = parse_qs(self.rfile.read(length), keep_blank_values=1)
else:
postvars = {}
return postvars
def do_POST(self):
'''
Perform the encryption in Python
'''
if self.path == "/encrypt":
postvars = self.parse_POST()
if postvars:
to_encrypt = ''.join(postvars["to_encrypt"])
iv, encrypted = Cryptor.encrypt(to_encrypt, Cryptor.KEY)
result = {
"key": Cryptor.KEY,
"iv": iv,
"ciphertext": binascii.b2a_base64(encrypted).rstrip()
}
#print "Encrypt result: %s" % result
self._return_json(result)
else:
print "Error: POST received no data."
self._return_http_code(500)
else:
self._return_http_code(404)
return
# ------------------------------
# START WEB SERVER
try:
#Create a web server and define the handler to manage the
#incoming request
server = HTTPServer(('', EncryptHandler.PORT_NUMBER), EncryptHandler)
print 'Started httpserver on port ' , EncryptHandler.PORT_NUMBER
#Wait forever for incoming htto requests
server.serve_forever()
except KeyboardInterrupt:
print '^C received, shutting down the web server'
server.socket.close()
@kodeine
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kodeine commented Jul 21, 2017

It does not work on Python 3.4, can you please port it to py3?

return in_string.ljust(in_len + pad_size, chr(pad_size)).encode()
TypeError: must be a byte string of length 1, not str

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