jlinoff/mycrypt.py

## mycrypt.py
#!/usr/bin/env python
'''
Implement openssl compatible AES-256 CBC mode encryption/decryption.

*********************************
UPDATE: 2021-08-28
Apparently this no longer works out of the box. That is probavbly because the
pycrypto package is getting stale.

I found this hacky workaround to get things working but it is likely not safe:

$ pip install pycrypto
$ MY_SITE_PATH=$(python -c 'import site; print(site.getsitepackages()[0])')
$ mv $MY_SITE_PATH/{c,C}rypto

STACKOVERFLOW:
This is where the problem was first pointed out.
https://stackoverflow.com/questions/16761458/how-to-decrypt-openssl-aes-encrypted-files-in-python/42773185#comment121764853_42773185

ADDITIONAL INFO:
https://crypto.stackexchange.com/questions/3298/is-there-a-standard-for-openssl-interoperable-aes-encryption
*********************************

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 AES  # pycrypto package NOT crypto!

VERSION='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 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)
    if isinstance(plaintext, str):
        padded_plaintext = plaintext + (chr(padding_len) * padding_len)
    else: # assume bytes
        padded_plaintext = plaintext + (bytearray([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 = b'Salted__' + salt + ciphertext
    b64 = base64.b64encode(openssl_ciphertext)
    if not chunkit:
        return b64

    LINELEN = 64
    chunk = 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 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
    if 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):
            continue
        filtered += line + nl

    # Base64 decode
    raw = 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 ciphertext
    ciphertext = raw[16:]

    # Decrypt
    cipher = 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.stdin
    ofp = sys.stdout

    if 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:
                break
            print('')
            print('Passphrases do not match, please try again.')
    else:
        passphrase = args.passphrase

    ifp, 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.passphrase

    ifp, 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 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: {}'.format(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 = os.path.abspath(sys.argv[0]).encode('utf-8')
    mebase = 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: {0} -> {0} (MD5)
        $ # Encrypt and decrypt using {0}.
        $ echo 'Lorem ipsum dolor sit amet' | \\
            {0} -e -p secret | \\
            {0} -d -p secret
        Lorem ipsum dolor sit amet

    EXAMPLE 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:secret
        Lorem ipsum dolor sit amet

    EXAMPLE 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 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: {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 secret
        Lorem ipsum dolor sit amet

    EXAMPLE 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:secret
        Lorem ipsum dolor sit amet

    EXAMPLE 7:
        $ # Run internal tests.
        $ {0} -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
'''.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()

## test.sh
#!/usr/bin/env bash
#
# Test mycrypt.py.
#

# ================================================================
# Functions
# ================================================================
# Print an info message with context (caller line number)
function info() {
    local Msg="$*"
    echo -e "INFO:${BASH_LINENO[0]}: $Msg"
}

function Test() {
    local Memo="$1"
    shift
    local Cmd="$*"
    local LineNum=${BASH_LINENO[0]}
    (( Total++ ))
    echo
    echo "INFO:${LineNum}: cmd.run=$Cmd"
    local Tid=$(printf '%03d' $Total)
    printf "test:%s:%s:cmd " "$Tid" "$LineNum" "$Memo"
    echo "$Cmd"
    eval "$Cmd"
    local st=$?
    echo "INFO:${LineNum}: cmd.status=$st"
    if (( st )) ; then
        echo "ERROR:${LineNum}: command failed"
        (( Failed++ ))
        printf "test:%s:%s:failed %s\n" $Tid "$LineNum" "$Memo"
        Done
    else
        (( Passed++ ))
        printf "test:%s:%03d:passed %s\n" $Tid "$LineNum" "$Memo"
    fi
}

function Runcmd() {
    local Cmd="$*"
    local LineNum=${BASH_LINENO[0]}
    echo
    echo "INFO:${LineNum}: cmd.run=$Cmd"
    eval "$Cmd"
    local st=$?
    echo "INFO:${LineNum}: cmd.status=$st"
    if (( st )) ; then
        echo "ERROR:${LineNum}: command failed"
        exit 1
    fi
}

function Done() {
    echo
    printf "test:total:passed  %3d\n" $Passed
    printf "test:total:failed  %3d\n" $Failed
    printf "test:total:summary %3d\n" $Total

    echo
    if (( Failed )) ; then
        echo "FAILED"
    else
        echo "PASSED"
    fi
    exit $Failed
}

# ================================================================
# Main
# ================================================================
Total=0
Passed=0
Failed=0
Pythons=('python2.7' 'python3.6')
Phrase='Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do'
for Py in ${Pythons[@]} ; do
    Test 'pipe-mycrypt-to-mycrypt' echo "'$Phrase'" '|' $Py mycrypt.py -e -p secret '|' $Py mycrypt.py -d -p secret
    Test 'pipe-openssl-to-mycrypt' echo "'$Phrase'" '|' openssl enc -aes-256-cbc -e -a -salt -pass pass:secret '|'  $Py mycrypt.py -d -p secret
    Test 'pipe-mycrypt-to-openssl' echo "'$Phrase'" '|' $Py mycrypt.py -e -p secret '|' openssl enc -aes-256-cbc -d -a -salt -pass pass:secret

    Runcmd echo "'$Phrase'" '>' test.txt
    Test 'file-mycrypt-enc' $Py mycrypt.py -e -p secret -i test.txt -o test.txt.enc
    Test 'lock-exists' '[' -e 'test.txt.enc' ']'
    Test 'openssl-dec' openssl enc -aes-256-cbc -d -a -salt -pass pass:secret -in test.txt.enc -out test.txt.dec
    Test 'diff-test' diff test.txt test.txt.dec
    Runcmd rm -f test.txt test.txt.enc test.txt.dec

    Runcmd echo "'$Phrase'" '>' test.txt
    Test 'openssl-enc' openssl enc -aes-256-cbc -e -a -salt -pass pass:secret -in test.txt -out test.txt.enc
    Test 'lock-exists' '[' -e 'test.txt.enc' ']'
    Test 'mycrypt-dec' $Py mycrypt.py -d -p secret -i test.txt.enc -o test.txt.dec
    Test 'diff-test' diff test.txt test.txt.dec
    Runcmd rm -f test.txt test.txt.enc test.txt.dec
done
Done
	#!/usr/bin/env python
	'''
	Implement openssl compatible AES-256 CBC mode encryption/decryption.

	*********************************
	UPDATE: 2021-08-28
	Apparently this no longer works out of the box. That is probavbly because the
	pycrypto package is getting stale.

	I found this hacky workaround to get things working but it is likely not safe:

	$ pip install pycrypto
	$ MY_SITE_PATH=$(python -c 'import site; print(site.getsitepackages()[0])')
	$ mv $MY_SITE_PATH/{c,C}rypto

	STACKOVERFLOW:
	This is where the problem was first pointed out.
	https://stackoverflow.com/questions/16761458/how-to-decrypt-openssl-aes-encrypted-files-in-python/42773185#comment121764853_42773185

	ADDITIONAL INFO:
	https://crypto.stackexchange.com/questions/3298/is-there-a-standard-for-openssl-interoperable-aes-encryption
	*********************************

	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 AES # pycrypto package NOT crypto!

	VERSION='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 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)
	if isinstance(plaintext, str):
	padded_plaintext = plaintext + (chr(padding_len) * padding_len)
	else: # assume bytes
	padded_plaintext = plaintext + (bytearray([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 = b'Salted__' + salt + ciphertext
	b64 = base64.b64encode(openssl_ciphertext)
	if not chunkit:
	return b64

	LINELEN = 64
	chunk = 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 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
	if 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):
	continue
	filtered += line + nl

	# Base64 decode
	raw = 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 ciphertext
	ciphertext = raw[16:]

	# Decrypt
	cipher = 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.stdin
	ofp = sys.stdout

	if 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:
	break
	print('')
	print('Passphrases do not match, please try again.')
	else:
	passphrase = args.passphrase

	ifp, 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.passphrase

	ifp, 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 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: {}'.format(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 = os.path.abspath(sys.argv[0]).encode('utf-8')
	mebase = 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: {0} -> {0} (MD5)
	$ # Encrypt and decrypt using {0}.
	$ echo 'Lorem ipsum dolor sit amet' \| \\
	{0} -e -p secret \| \\
	{0} -d -p secret
	Lorem ipsum dolor sit amet

	EXAMPLE 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:secret
	Lorem ipsum dolor sit amet

	EXAMPLE 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 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: {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 secret
	Lorem ipsum dolor sit amet

	EXAMPLE 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:secret
	Lorem ipsum dolor sit amet

	EXAMPLE 7:
	$ # Run internal tests.
	$ {0} -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
	'''.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()
	#!/usr/bin/env bash
	#
	# Test mycrypt.py.
	#

	# ================================================================
	# Functions
	# ================================================================
	# Print an info message with context (caller line number)
	function info() {
	local Msg="$*"
	echo -e "INFO:${BASH_LINENO[0]}: $Msg"
	}

	function Test() {
	local Memo="$1"
	shift
	local Cmd="$*"
	local LineNum=${BASH_LINENO[0]}
	(( Total++ ))
	echo
	echo "INFO:${LineNum}: cmd.run=$Cmd"
	local Tid=$(printf '%03d' $Total)
	printf "test:%s:%s:cmd " "$Tid" "$LineNum" "$Memo"
	echo "$Cmd"
	eval "$Cmd"
	local st=$?
	echo "INFO:${LineNum}: cmd.status=$st"
	if (( st )) ; then
	echo "ERROR:${LineNum}: command failed"
	(( Failed++ ))
	printf "test:%s:%s:failed %s\n" $Tid "$LineNum" "$Memo"
	Done
	else
	(( Passed++ ))
	printf "test:%s:%03d:passed %s\n" $Tid "$LineNum" "$Memo"
	fi
	}

	function Runcmd() {
	local Cmd="$*"
	local LineNum=${BASH_LINENO[0]}
	echo
	echo "INFO:${LineNum}: cmd.run=$Cmd"
	eval "$Cmd"
	local st=$?
	echo "INFO:${LineNum}: cmd.status=$st"
	if (( st )) ; then
	echo "ERROR:${LineNum}: command failed"
	exit 1
	fi
	}

	function Done() {
	echo
	printf "test:total:passed %3d\n" $Passed
	printf "test:total:failed %3d\n" $Failed
	printf "test:total:summary %3d\n" $Total

	echo
	if (( Failed )) ; then
	echo "FAILED"
	else
	echo "PASSED"
	fi
	exit $Failed
	}

	# ================================================================
	# Main
	# ================================================================
	Total=0
	Passed=0
	Failed=0
	Pythons=('python2.7' 'python3.6')
	Phrase='Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do'
	for Py in ${Pythons[@]} ; do
	Test 'pipe-mycrypt-to-mycrypt' echo "'$Phrase'" '\|' $Py mycrypt.py -e -p secret '\|' $Py mycrypt.py -d -p secret
	Test 'pipe-openssl-to-mycrypt' echo "'$Phrase'" '\|' openssl enc -aes-256-cbc -e -a -salt -pass pass:secret '\|' $Py mycrypt.py -d -p secret
	Test 'pipe-mycrypt-to-openssl' echo "'$Phrase'" '\|' $Py mycrypt.py -e -p secret '\|' openssl enc -aes-256-cbc -d -a -salt -pass pass:secret

	Runcmd echo "'$Phrase'" '>' test.txt
	Test 'file-mycrypt-enc' $Py mycrypt.py -e -p secret -i test.txt -o test.txt.enc
	Test 'lock-exists' '[' -e 'test.txt.enc' ']'
	Test 'openssl-dec' openssl enc -aes-256-cbc -d -a -salt -pass pass:secret -in test.txt.enc -out test.txt.dec
	Test 'diff-test' diff test.txt test.txt.dec
	Runcmd rm -f test.txt test.txt.enc test.txt.dec

	Runcmd echo "'$Phrase'" '>' test.txt
	Test 'openssl-enc' openssl enc -aes-256-cbc -e -a -salt -pass pass:secret -in test.txt -out test.txt.enc
	Test 'lock-exists' '[' -e 'test.txt.enc' ']'
	Test 'mycrypt-dec' $Py mycrypt.py -d -p secret -i test.txt.enc -o test.txt.dec
	Test 'diff-test' diff test.txt test.txt.dec
	Runcmd rm -f test.txt test.txt.enc test.txt.dec
	done
	Done