#!/usr/bin/env 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
#
# MIT Open Source
#
# 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 inspect
import sys
from getpass import getpass
from Crypto.Cipher import AESVERSION='1.2'# ================================================================
# debug
# ================================================================
def _debug(msg, lev=1):'''Print a debug message with some context.'''sys.stderr.write('DEBUG:{} ofp {}\n'.format(inspect.stack()[lev][2], msg))# ================================================================
# 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 ofthe 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 mdfmdf = getattr(__import__('hashlib', fromlist=[msgdgst]), msgdgst)password = password.encode('ascii', 'ignore')  # convert to ASCIItry:maxlen = klen + ilenkeyiv = mdf(password + salt).digest()tmp = [keyiv]while len(tmp) < maxlen:tmp.append( mdf(tmp[-1] + password + salt).digest() )keyiv += tmp[-1]  # append the last bytekey = keyiv[:klen]iv = keyiv[klen:klen+ilen]return key, ivexcept UnicodeDecodeError:return None, None# ================================================================
# encrypt
# ================================================================
def encrypt(password, plaintext, chunkit=True, msgdgst='md5'):'''Encrypt the plaintext using the password using an opensslcompatible encryption algorithm. It is the same as creating a filewith 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 ciphertextinto 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 paddingpadding_len = 16 - (len(plaintext) % 16)if isinstance(plaintext, str):padded_plaintext = plaintext + (chr(padding_len) * padding_len)else: # assume bytespadded_plaintext = plaintext + (bytearray([padding_len] * padding_len))# Encryptcipher = 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 = b'Salted__' + salt + ciphertextb64 = base64.b64encode(openssl_ciphertext)if not chunkit:return b64LINELEN = 64chunk = lambda s: b'\n'.join(s[i:min(i+LINELEN, len(s))]for i in range(0, len(s), LINELEN))return chunk(b64)# ================================================================
# decrypt
# ================================================================
def decrypt(password, ciphertext, msgdgst='md5'):'''Decrypt the ciphertext using the password using an opensslcompatible decryption algorithm. It is the same as creating a filewith ciphertext contents and running openssl like this:$ cat ciphertext# ENCRYPTED<ciphertext>$ egrep -v '^#|^$' | \\openssl enc -d -aes-256-cbc -base64 -salt -pass pass:<password> -in ciphertext@param password   The password.@param ciphertext The ciphertext to decrypt.@param msgdgst    The message digest algorithm.@returns the decrypted data.'''# unfilter -- ignore blank lines and commentsif isinstance(ciphertext, str):filtered = ''nl = '\n're1 = r'^\s*$'re2 = r'^\s*#'else:filtered = b''nl = b'\n're1 = b'^\\s*$'re2 = b'^\\s*#'for line in ciphertext.split(nl):line = line.strip()if re.search(re1,line) or re.search(re2, line):continuefiltered += line + nl# Base64 decoderaw = base64.b64decode(filtered)assert(raw[:8] == b'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 ciphertextciphertext = raw[16:]# Decryptcipher = AES.new(key, AES.MODE_CBC, iv)padded_plaintext = cipher.decrypt(ciphertext)if isinstance(padded_plaintext, str):padding_len = ord(padded_plaintext[-1])else:padding_len = padded_plaintext[-1]plaintext = padded_plaintext[:-padding_len]return plaintext# include the code above ...
# ================================================================
# _open_ios
# ================================================================
def _open_ios(args):'''Open the IO files.'''ifp = sys.stdinofp = sys.stdoutif args.input is not None:try:ifp = open(args.input, 'rb')except IOError:print('ERROR: cannot read file: {}'.format(args.input))sys.exit(1)if args.output is not None:try:ofp = open(args.output, 'wb')except IOError:print('ERROR: cannot write file: {}'.format(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()# ================================================================
# _write
# ================================================================
def _write(ofp, out, newline=False):'''Write out the data in the correct format.'''if ofp == sys.stdout and isinstance(out, bytes):out = out.decode('utf-8', 'ignored')ofp.write(out)if newline:ofp.write('\n')elif isinstance(out, str):ofp.write(out)if newline:ofp.write('\n')else:  # assume bytes
        ofp.write(out)if newline:ofp.write(b'\n')# ================================================================
# _write
# ================================================================
def _read(ifp):'''Read the data in the correct format.'''return ifp.read()# ================================================================
# _runenc
# ================================================================
def _runenc(args):'''Encrypt data.'''if args.passphrase is None:while True:passphrase = getpass('Passphrase: ')tmp = getpass('Re-enter passphrase: ')if passphrase == tmp:breakprint('')print('Passphrases do not match, please try again.')else:passphrase = args.passphraseifp, ofp = _open_ios(args)text = _read(ifp)out = encrypt(passphrase, text, msgdgst=args.msgdgst)_write(ofp, out, True)_close_ios(ifp, ofp)# ================================================================
# _rundec
# ================================================================
def _rundec(args):'''Decrypt data.'''if args.passphrase is None:passphrase = getpass('Passphrase: ')else:passphrase = args.passphraseifp, ofp = _open_ios(args)text = _read(ifp)out = decrypt(passphrase, text, msgdgst=args.msgdgst)_write(ofp, out, False)_close_ios(ifp, ofp)# ================================================================
# _runtest
# ================================================================
def _runtest(args):'''Run a series of iteration where each iteration generates a randompassword from 8-32 characters and random text from 20 to 256characters. The encrypts and decrypts the random data. It thencompares the results to make sure that everything works correctly.The test output looks like this:$ crypt 20002000 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 stringimport randomfrom random import randint# Encrypt/decrypt N random sets of plaintext and passwords.num = args.testofp = sys.stdoutif args.output is not None:try:ofp = open(args.output, 'w')except IOError:print('ERROR: can open file for writing: {}'.format(args.output))sys.exit(1)chset = string.printablepassed = 0failed = []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 += 1output = '%*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 = os.path.abspath(sys.argv[0]).encode('utf-8')mebase = os.path.basename(mepath)description = '''Implements encryption/decryption that is compatible with opensslAES-256 CBC mode.You can use it as follows:EXAMPLE 1: {0} -> {0} (MD5)$ # Encrypt and decrypt using {0}.$ echo 'Lorem ipsum dolor sit amet' | \\{0} -e -p secret | \\{0} -d -p secretLorem ipsum dolor sit ametEXAMPLE 2: {0} -> openssl (MD5)$ # Encrypt using {0} and decrypt using openssl.$ echo 'Lorem ipsum dolor sit amet' | \\{0} -e -p secret | \\openssl enc -d -aes-256-cbc -md md5 -base64 -salt -pass pass:secretLorem ipsum dolor sit ametEXAMPLE 3: openssl -> {0} (MD5)$ # Encrypt using openssl and decrypt using {0}$ echo 'Lorem ipsum dolor sit amet' | \\openssl enc -e -aes-256-cbc -md md5 -base64 -salt -pass pass:secret{0} -d -p secretLorem ipsum dolor sit ametEXAMPLE 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:secretopenssl enc -d -aes-256-cbc -md md5 -base64 -salt -pass pass:secretLorem ipsum dolor sit ametEXAMPLE 5: {0} -> {0} (SHA512)$ # Encrypt and decrypt using {0}.$ echo 'Lorem ipsum dolor sit amet' | \\{0} -e -m sha512 -p secret | \\{0} -d -m sha512 -p secretLorem ipsum dolor sit ametEXAMPLE 6: {0} -> openssl (SHA512)$ # Encrypt using {0} and decrypt using openssl.$ echo 'Lorem ipsum dolor sit amet' | \\{0} -e -m sha512 -p secret | \\openssl enc -d -aes-256-cbc -md sha1=512 -base64 -salt -pass pass:secretLorem ipsum dolor sit ametEXAMPLE 7:$ # Run internal tests.$ {0} -t 20002000 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
'''.format(mebase.decode('ascii', 'ignore'))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()