This is an example how to write an encrypted file using Python, so that it can be decrypted using openssl.
Thanks for Joe Linoff for the code.
This is an example how to write an encrypted file using Python, so that it can be decrypted using openssl.
Thanks for Joe Linoff for the code.
FROM python:2.7-alpine | |
ENV PYTHONUNBUFFERED True | |
RUN apk add --update openssl py-pip build-base python-dev \ | |
&& pip install pycrypto \ | |
&& apk del build-base python-dev \ | |
&& rm -rf /var/cache/apk/* | |
ADD . /app/ | |
WORKDIR /app | |
RUN chmod u+x /app/test.sh | |
CMD "/app/test.sh" | |
#!/usr/bin/env python | |
#!python | |
''' | |
Implement openssl compatible AES-256 CBC mode encryption/decryption. | |
This module provides encrypt() and decrypt() functions that are compatible | |
with the openssl algorithms. | |
This is basically a python encoding of my C++ work on the Cipher class | |
using the Crypto.Cipher.AES class. | |
URL: http://projects.joelinoff.com/cipher-1.1/doxydocs/html/ | |
''' | |
# LICENSE | |
# | |
# Copyright (c) 2014 Joe Linoff | |
# | |
# 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. | |
import argparse | |
import base64 | |
import os | |
import re | |
import hashlib | |
import sys | |
from getpass import getpass | |
from Crypto.Cipher import AES | |
VERSION='1.1' | |
# ================================================================ | |
# get_key_and_iv | |
# ================================================================ | |
def get_key_and_iv(password, salt, klen=32, ilen=16, msgdgst='md5'): | |
''' | |
Derive the key and the IV from the given password and salt. | |
This is a niftier implementation than my direct transliteration of | |
the C++ code although I modified to support different digests. | |
CITATION: http://stackoverflow.com/questions/13907841/implement-openssl-aes-encryption-in-python | |
@param password The password to use as the seed. | |
@param salt The salt. | |
@param klen The key length. | |
@param ilen The initialization vector length. | |
@param msgdgst The message digest algorithm to use. | |
''' | |
# equivalent to: | |
# from hashlib import <mdi> as mdf | |
# from hashlib import md5 as mdf | |
# from hashlib import sha512 as mdf | |
mdf = getattr(__import__('hashlib', fromlist=[msgdgst]), msgdgst) | |
password = password.encode('ascii','ignore') # convert to ASCII | |
try: | |
maxlen = klen + ilen | |
keyiv = mdf(password + salt).digest() | |
tmp = [keyiv] | |
while len(tmp) < maxlen: | |
tmp.append( mdf(tmp[-1] + password + salt).digest() ) | |
keyiv += tmp[-1] # append the last byte | |
key = keyiv[:klen] | |
iv = keyiv[klen:klen+ilen] | |
return key, iv | |
except UnicodeDecodeError: | |
return None, None | |
# ================================================================ | |
# encrypt | |
# ================================================================ | |
def encrypt(password, plaintext, chunkit=True, msgdgst='md5'): | |
''' | |
Encrypt the plaintext using the password using an openssl | |
compatible encryption algorithm. It is the same as creating a file | |
with plaintext contents and running openssl like this: | |
$ cat plaintext | |
<plaintext> | |
$ openssl enc -e -aes-256-cbc -base64 -salt \\ | |
-pass pass:<password> -n plaintext | |
@param password The password. | |
@param plaintext The plaintext to encrypt. | |
@param chunkit Flag that tells encrypt to split the ciphertext | |
into 64 character (MIME encoded) lines. | |
This does not affect the decrypt operation. | |
@param msgdgst The message digest algorithm. | |
''' | |
salt = os.urandom(8) | |
key, iv = get_key_and_iv(password, salt, msgdgst=msgdgst) | |
if key is None: | |
return None | |
# PKCS#7 padding | |
padding_len = 16 - (len(plaintext) % 16) | |
padded_plaintext = plaintext + (chr(padding_len) * padding_len) | |
# Encrypt | |
cipher = AES.new(key, AES.MODE_CBC, iv) | |
ciphertext = cipher.encrypt(padded_plaintext) | |
# Make openssl compatible. | |
# I first discovered this when I wrote the C++ Cipher class. | |
# CITATION: http://projects.joelinoff.com/cipher-1.1/doxydocs/html/ | |
openssl_ciphertext = 'Salted__' + salt + ciphertext | |
b64 = base64.b64encode(openssl_ciphertext) | |
if not chunkit: | |
return b64 | |
LINELEN = 64 | |
chunk = lambda s: '\n'.join(s[i:min(i+LINELEN, len(s))] | |
for i in xrange(0, len(s), LINELEN)) | |
return chunk(b64) | |
# ================================================================ | |
# decrypt | |
# ================================================================ | |
def decrypt(password, ciphertext, msgdgst='md5'): | |
''' | |
Decrypt the ciphertext using the password using an openssl | |
compatible decryption algorithm. It is the same as creating a file | |
with ciphertext contents and running openssl like this: | |
$ cat ciphertext | |
# ENCRYPTED | |
<ciphertext> | |
$ egrep -v '^#|^$' | \\ | |
openssl enc -d -aes-256-cbc -base64 -salt -pass pass:<password> -in ciphertext | |
@param password The password. | |
@param ciphertext The ciphertext to decrypt. | |
@param msgdgst The message digest algorithm. | |
@returns the decrypted data. | |
''' | |
# unfilter -- ignore blank lines and comments | |
filtered = '' | |
for line in ciphertext.split('\n'): | |
line = line.strip() | |
if re.search('^\s*$', line) or re.search('^\s*#', line): | |
continue | |
filtered += line + '\n' | |
# Base64 decode | |
raw = base64.b64decode(filtered) | |
assert( raw[:8] == 'Salted__' ) | |
salt = raw[8:16] # get the salt | |
# Now create the key and iv. | |
key, iv = get_key_and_iv(password, salt, msgdgst=msgdgst) | |
if key is None: | |
return None | |
# The original ciphertext | |
ciphertext = raw[16:] | |
# Decrypt | |
cipher = AES.new(key, AES.MODE_CBC, iv) | |
padded_plaintext = cipher.decrypt(ciphertext) | |
padding_len = ord(padded_plaintext[-1]) | |
plaintext = padded_plaintext[:-padding_len] | |
return plaintext | |
# ================================================================ | |
# _open_ios | |
# ================================================================ | |
def _open_ios(args): | |
''' | |
Open the IO files. | |
''' | |
ifp = sys.stdin | |
ofp = sys.stdout | |
if args.input is not None: | |
try: | |
ifp = open(args.input, 'r') | |
except IOError: | |
print 'ERROR: can\'t read file: %s' % (args.input) | |
sys.exit(1) | |
if args.output is not None: | |
try: | |
ifp = open(args.output, 'w') | |
except IOError: | |
print 'ERROR: can\'t write file: %s' % (args.output) | |
sys.exit(1) | |
return ifp, ofp | |
# ================================================================ | |
# _close_ios | |
# ================================================================ | |
def _close_ios(ifp, ofp): | |
''' | |
Close the IO files if necessary. | |
''' | |
if ifp != sys.stdin: | |
ifp.close() | |
if ofp != sys.stdout: | |
ofp.close() | |
# ================================================================ | |
# _runenc | |
# ================================================================ | |
def _runenc(args): | |
''' | |
Encrypt data. | |
''' | |
if args.passphrase is None: | |
while True: | |
passphrase = getpass('Passphrase: ') | |
tmp = getpass('Re-enter passphrase: ') | |
if passphrase == tmp: | |
break | |
print 'Passphrases don\'t match, please try again.' | |
else: | |
passphrase = args.passphrase | |
ifp, ofp = _open_ios(args) | |
text = ifp.read() | |
out = encrypt(passphrase, text, msgdgst=args.msgdgst) | |
ofp.write(out+'\n') | |
_close_ios(ifp, ofp) | |
# ================================================================ | |
# _rundec | |
# ================================================================ | |
def _rundec(args): | |
''' | |
Decrypt data. | |
''' | |
if args.passphrase is None: | |
passphrase = getpass('Passphrase: ') | |
else: | |
passphrase = args.passphrase | |
ifp, ofp = _open_ios(args) | |
text = ifp.read() | |
out = decrypt(passphrase, text, msgdgst=args.msgdgst) | |
ofp.write(out) | |
_close_ios(ifp, ofp) | |
# ================================================================ | |
# _runtest | |
# ================================================================ | |
def _runtest(args): | |
''' | |
Run a series of iteration where each iteration generates a random | |
password from 8-32 characters and random text from 20 to 256 | |
characters. The encrypts and decrypts the random data. It then | |
compares the results to make sure that everything works correctly. | |
The test output looks like this: | |
$ crypt 2000 | |
2000 of 2000 100.00% 15 139 2000 0 | |
$ # ^ ^ ^ ^ ^ ^ | |
$ # | | | | | +-- num failed | |
$ # | | | | +---------- num passed | |
$ # | | | +-------------- size of text for a test | |
$ # | | +----------------- size of passphrase for a test | |
$ # | +-------------------------- percent completed | |
$ # +------------------------------- total | |
# #+------------------------------------ current test | |
@param args The args parse arguments. | |
''' | |
import string | |
import random | |
from random import randint | |
# Encrypt/decrypt N random sets of plaintext and passwords. | |
num = args.test | |
ofp = sys.stdout | |
if args.output is not None: | |
try: | |
ofp = open(args.output, 'w') | |
except IOError: | |
print 'ERROR: can open file for writing: %s' % (args.output) | |
sys.exit(1) | |
chset = string.printable | |
passed = 0 | |
failed = [] | |
maxlen = len(str(num)) | |
for i in range(num): | |
ran1 = randint(8,32) | |
password = ''.join(random.choice(chset) for x in range(ran1)) | |
ran2 = randint(20, 256) | |
plaintext = ''.join(random.choice(chset) for x in range(ran2)) | |
ciphertext = encrypt(password, plaintext, msgdgst=args.msgdgst) | |
verification = decrypt(password, ciphertext, msgdgst=args.msgdgst) | |
if plaintext != verification: | |
failed.append( [password, plaintext] ) | |
else: | |
passed += 1 | |
output = '%*d of %d %6.2f%% %3d %3d %*d %*d %s' % (maxlen,i+1, | |
num, | |
100*(i+1)/num, | |
len(password), | |
len(plaintext), | |
maxlen, passed, | |
maxlen, len(failed), | |
args.msgdgst) | |
if args.output is None: | |
ofp.write('\b'*80) | |
ofp.write(output) | |
ofp.flush() | |
else: | |
ofp.write(output+'\n') | |
ofp.write('\n') | |
if len(failed): | |
for i in range(len(failed)): | |
ofp.write('%3d %2d %-34s %3d %s\n' % (i, | |
len(failed[i][0]), | |
'"'+failed[i][0]+'"', | |
len(failed[i][1]), | |
'"'+failed[i][1]+'"')) | |
ofp.write('\n') | |
if args.output is not None: | |
ofp.close() | |
# ================================================================ | |
# _cli_opts | |
# ================================================================ | |
def _cli_opts(): | |
''' | |
Parse command line options. | |
@returns the arguments | |
''' | |
mepath = unicode(os.path.abspath(sys.argv[0])) | |
mebase = '%s' % (os.path.basename(mepath)) | |
description = ''' | |
Implements encryption/decryption that is compatible with openssl | |
AES-256 CBC mode. | |
You can use it as follows: | |
EXAMPLE 1: %s -> %s (MD5) | |
$ # Encrypt and decrypt using %s. | |
$ echo 'Lorem ipsum dolor sit amet' | \\ | |
%s -e -p secret | \\ | |
%s -d -p secret | |
Lorem ipsum dolor sit amet | |
EXAMPLE 2: %s -> openssl (MD5) | |
$ # Encrypt using %s and decrypt using openssl. | |
$ echo 'Lorem ipsum dolor sit amet' | \\ | |
%s -e -p secret | \\ | |
openssl enc -d -aes-256-cbc -md md5 -base64 -salt -pass pass:secret | |
Lorem ipsum dolor sit amet | |
EXAMPLE 3: openssl -> %s (MD5) | |
$ # Encrypt using openssl and decrypt using %s | |
$ echo 'Lorem ipsum dolor sit amet' | \\ | |
openssl enc -e -aes-256-cbc -md md5 -base64 -salt -pass pass:secret | |
%s -d -p secret | |
Lorem ipsum dolor sit amet | |
EXAMPLE 4: openssl -> openssl (MD5) | |
$ # Encrypt and decrypt using openssl | |
$ echo 'Lorem ipsum dolor sit amet' | \\ | |
openssl enc -e -aes-256-cbc -md md5 -base64 -salt -pass pass:secret | |
openssl enc -d -aes-256-cbc -md md5 -base64 -salt -pass pass:secret | |
Lorem ipsum dolor sit amet | |
EXAMPLE 5: %s -> %s (SHA512) | |
$ # Encrypt and decrypt using %s. | |
$ echo 'Lorem ipsum dolor sit amet' | \\ | |
%s -e -m sha512 -p secret | \\ | |
%s -d -m sha512 -p secret | |
Lorem ipsum dolor sit amet | |
EXAMPLE 6: %s -> openssl (SHA512) | |
$ # Encrypt using %s and decrypt using openssl. | |
$ echo 'Lorem ipsum dolor sit amet' | \\ | |
%s -e -m sha512 -p secret | \\ | |
openssl enc -d -aes-256-cbc -md sha1=512 -base64 -salt -pass pass:secret | |
Lorem ipsum dolor sit amet | |
EXAMPLE 7: | |
$ # Run internal tests. | |
$ %s -t 2000 | |
2000 of 2000 100.00%% 21 104 2000 0 md5 | |
$ # ^ ^ ^ ^ ^ ^ ^ | |
$ # | | | | | | +- message digest | |
$ # | | | | | +--- num failed | |
$ # | | | | +----------- num passed | |
$ # | | | +--------------- size of text for a test | |
$ # | | +------------------ size of passphrase for a test | |
$ # | +--------------------------- percent completed | |
$ # +-------------------------------- total | |
# #+------------------------------------- current test | |
''' % (mebase, mebase, mebase, mebase, | |
mebase, mebase, mebase, mebase, | |
mebase, mebase, mebase, mebase, | |
mebase, mebase, mebase, mebase, | |
mebase, mebase, mebase, mebase, | |
) | |
parser = argparse.ArgumentParser(prog=mebase, | |
formatter_class=argparse.RawDescriptionHelpFormatter, | |
description=description, | |
) | |
group = parser.add_mutually_exclusive_group(required=True) | |
group.add_argument('-d', '--decrypt', | |
action='store_true', | |
help='decryption mode') | |
group.add_argument('-e', '--encrypt', | |
action='store_true', | |
help='encryption mode') | |
parser.add_argument('-i', '--input', | |
action='store', | |
help='input file, default is stdin') | |
parser.add_argument('-m', '--msgdgst', | |
action='store', | |
default='md5', | |
help='message digest (md5, sha, sha1, sha256, sha512), default is md5') | |
parser.add_argument('-o', '--output', | |
action='store', | |
help='output file, default is stdout') | |
parser.add_argument('-p', '--passphrase', | |
action='store', | |
help='passphrase for encrypt/decrypt operations') | |
group.add_argument('-t', '--test', | |
action='store', | |
default=-1, | |
type=int, | |
help='test mode (TEST is an integer)') | |
parser.add_argument('-v', '--verbose', | |
action='count', | |
help='the level of verbosity') | |
parser.add_argument('-V', '--version', | |
action='version', | |
version='%(prog)s '+VERSION) | |
args = parser.parse_args() | |
return args | |
# ================================================================ | |
# main | |
# ================================================================ | |
def main(): | |
args = _cli_opts() | |
if args.test > 0: | |
if args.input is not None: | |
print 'WARNING: input argument will be ignored.' | |
if args.passphrase is not None: | |
print 'WARNING: passphrase argument will be ignored.' | |
_runtest(args) | |
elif args.encrypt: | |
_runenc(args) | |
elif args.decrypt: | |
_rundec(args) | |
# ================================================================ | |
# MAIN | |
# ================================================================ | |
if __name__ == "__main__": | |
main() |
# coding: utf8 | |
from mycrypt import encrypt | |
encrypted = encrypt("passphrase", "This is öur test\ntext which is a bit longer this time but does break\nin multiple locations likely\n") | |
with open("./encrypted", "w") as encfile: | |
encfile.write(encrypted + "\n") |
#!/bin/sh | |
echo "Creating encrypted file" | |
python ./test.py | |
echo "Encrypted text:" | |
cat encrypted | |
echo "" | |
echo "Attempting decryption" | |
export PASSWORD=passphrase | |
openssl aes-256-cbc -d -a -pass env:PASSWORD -in ./encrypted -out decrypted | |
echo "Result:" | |
cat decrypted | |