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ls47/lc4.py

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#!/usr/bin/python2
# -*- coding: utf-8 -*-
# This software is hereby released into public domain. Use it wisely.
#
# ElsieFour (LC4) and its enhancement LS47
# version 2.8.1 (2018-07-24)
#
# Original paper by Alan Kaminsky: https://eprint.iacr.org/2017/339.pdf
# Original LC4 Java source: https://www.cs.rit.edu/~ark/parallelcrypto/elsiefour/
#
# - Python 2 script for LS47 originally written by Mirek Kratochvil (2017)
# See https://gitea.blesmrt.net/exa/ls47
# - Python 3 port by Bernhard Esslinger / AK (Feb 2018)
# See www.mysterytwisterc3.org
# - New options by CrypTool project (www.cryptool.org) (Feb 2018) in order to
# support both ciphers LC4 and LS47 in one program, to support both ways to
# deal with nonces and keywords, to support reading from file and commandline,
# and to extend test outputs (v2.7).
# - v2.8 extended the testcase and added the fix of the fixpoint-ish problem for ls47 (option -m1):
# python lc4.py -6 -ws thisismysecretkey -es ############## -ns igxf5e -m1
# igxf5egcyhoo#ny#o5i5
# python lc4.py -6 -ws thisismysecretkey -es ############## -ns igxf5e -m0
# igxf5e##############
#
# Sample calls:
#
# 1) Using cipher LC4, enforced with option -6:
# // encrypt (key, message). Following example returns tk5j23tq94_gw9c#lhzs
# python lc4.py -6 -ks s2ferw_nx346ty5odiupq#lmz8ajhgcvk79b -es aaaaaaaaaaaaaaaaaaaa
# // decrypt (key, message). Following example returns aaaaaaaaaaaaaaaaaaaa
# python lc4.py -6 -ks s2ferw_nx346ty5odiupq#lmz8ajhgcvk79b -ds tk5j23tq94_gw9c#lhzs
# python lc4.py -6 -ws thisismysecretkey -es its_my_fathers_son_but_not_my_brother
# python lc4.py -6 -ws thisismysecretkey -ds 6dudfy3u7omoxy4jbscgn37c2se_d8gx6ogk9
# python lc4.py -6 -ws thisismysecretkey -es its_my_fathers_son_but_not_my_brother -v -nl 6
# python lc4.py -6 -ws thisismysecretkey -ds q6xojffkncfyz#f5czs49#3mbsco#2iscvbnm#bymaf -v -nl 6
#
# 2) Using cipher LS47, enforced with option -7:
# python lc4.py -7 -ws s3cret_p4ssw0rd/31337 -es conflagrate_the_rose_bush_at_six!---peace-vector-3 -v -ns 8y(l._4ct' -m0
# python lc4.py -7 -ws s3cret_p4ssw0rd/31337 -ds y'zbvvs+d2,ky4sy?w(_wkz*7'90v:./s)kcz?mj+gyu8-'h(y,i+v,z+1ws -v -nl 10 -m0
# python lc4.py -7 -ws s3cret_p4ssw0rd/31337 -ds y'zbvvs+d2,ky4sy?w(_wkz*7'90v:./s)kcz?mj+gyu8-'h(y,i+v,z+1ws -v -ns 8y(l._4ct' -m0
#
# 3) Using the automatic test (option -t can be combined with options -s and -ws)
# python lc4.py -t
# python lc4.py -t -ws s3cret_p4sswxyz -s peacevector_34
from __future__ import print_function
import sys
import os
import random
import argparse
version = "v2.8.1 (2018-07-24)"
# define alphabet
letters6 = "#_23456789abcdefghijklmnopqrstuvwxyz"
letters6card = "abcdefghijklmnopqrstuvwxyz_23456789#"
letters7 = "_abcdefghijklmnopqrstuvwxyz.0123456789,-+*/:?!'()"
letters7card = "abcdefghijklmnopqrstuvwxyz_.,-+*/:?!'()1234567890"
def missing_letters(s,t):
return ''.join(sorted(set(c for c in s if c not in t)))
def check_key(key):
illegal = missing_letters(key,letters)
missing = missing_letters(letters,key)
duplicates = ''.join(sorted(c for c in letters if key.count(c)>1))
errors = []
if illegal: errors.append( "Key contains illegal letters: '%s'" % illegal )
if missing: errors.append( "Key misses some letters: '%s'" % missing )
if duplicates: errors.append( "Key contains duplicate letters: '%s'" % duplicates )
if errors:
errors.append( "The key must be a permutation of the alphabet: %s" % letters )
raise ValueError("\n".join(errors))
def check_nonce(nonce):
illegal = missing_letters(nonce,letters)
if illegal:
raise ValueError("Nonce contains illegal letters: '%s'" % illegal)
def check_plaintext(s):
illegal = missing_letters(s,letters)
if illegal:
raise ValueError("Plaintext contains illegal letters: '%s'" % illegal)
def check_ciphertext(s):
illegal = missing_letters(s,letters)
if illegal:
raise ValueError("Ciphertext contains illegal letters: '%s'" % illegal)
def find_ix(letter):
m = [l[1] for l in tiles if l[0] == letter]
if len(m) != 1:
raise ValueError("Letter '%c' not in the alphabet!" % letter)
return m[0]
def find_pos(key, letter):
p = key.find(letter)
if not (0 <= p < size * size):
raise ValueError("Letter '%c' not in key?!" % letter)
return (p // size, p % size)
def add_pos(a, b):
return ((a[0] + b[0]) % size, (a[1] + b[1]) % size)
def sub_pos(a, b):
return ((a[0] - b[0]) % size, (a[1] - b[1]) % size)
def find_at_pos(key, coord):
return key[coord[1] + coord[0] * size]
def rotate_right(key, row, n):
mid = key[size * row:size * (row + 1)]
return key[:size * row] + mid[-n:] + mid[:-n] + key[size * (row + 1):]
def rotate_down(key, col, n):
lines = [key[i * size:(i + 1) * size] for i in range(size)]
lefts = [l[:col] for l in lines]
mids = [l[col] for l in lines]
rights = [l[col + 1:] for l in lines]
mids = mids[-n:] + mids[:-n]
return ''.join(lefts[i] + mids[i] + rights[i] for i in range(size))
def rotate_marker_right(m, row, n):
if m[0] != row:
return (m[0], m[1])
else:
return (m[0], (m[1] + n) % size)
def rotate_marker_down(m, col, n):
if m[1] != col:
return (m[0], m[1])
else:
return ((m[0] + n) % size, m[1])
def derive_key(password, one_indexed):
i = 0
k = letters
# if using one-indexed arrays, moves the zero element to the end
if one_indexed: k = k[1:]+k[0]
for c in password:
(row, col) = find_ix(c)
k = rotate_down(rotate_right(k, i, col), i, row)
i = (i + 1) % size
return k
def encrypt(plaintext):
global key, mp
ciphertext = ''
for p in plaintext:
pp = find_pos(key, p)
mix = find_ix(find_at_pos(key, mp))
cp = add_pos(pp, mix)
c = find_at_pos(key, cp)
ciphertext += c
key = rotate_right(key, pp[0], 1)
if marker_mode==1: mp = rotate_marker_right(mp, pp[0], 1)
cp = find_pos(key, c)
key = rotate_down(key, cp[1], 1)
if marker_mode==1: mp = rotate_marker_down(mp, cp[1], 1)
mp = add_pos(mp, find_ix(c))
return ciphertext
def decrypt(ciphertext):
global key, mp
plaintext = ''
for c in ciphertext:
cp = find_pos(key, c)
mix = find_ix(find_at_pos(key, mp))
pp = sub_pos(cp, mix)
p = find_at_pos(key, pp)
plaintext += p
key = rotate_right(key, pp[0], 1)
if marker_mode==1: mp = rotate_marker_right(mp, pp[0], 1)
cp = find_pos(key, c)
key = rotate_down(key, cp[1], 1)
if marker_mode==1: mp = rotate_marker_down(mp, cp[1], 1)
mp = add_pos(mp, find_ix(c))
return plaintext
def create_random_nonce(size):
return ''.join(random.choice(letters) for i in range(size))
def encrypt_with_nonce(plaintext):
global nonce, nonce_enc
ciphertext = encrypt(nonce + plaintext)
nonce_enc = ciphertext[:nonce_size]
if nonce_mode==1:
return nonce + ciphertext[nonce_size:]
else:
return ciphertext
def decrypt_with_nonce(ciphertext):
global nonce, nonce_enc
if nonce_mode==1:
nonce = ciphertext[:nonce_size]
nonce_enc = encrypt(nonce)
return decrypt(ciphertext[nonce_size:])
else:
plaintext = decrypt(ciphertext)
nonce = plaintext[:nonce_size]
nonce_enc = ciphertext[:nonce_size]
return plaintext[nonce_size:]
def eprint(*args, **kwargs):
print(*args, file=sys.stderr, **kwargs)
def printinfo(enc=False): # used by test1() and when option -v
eprint('CIPHER : ' + ("LC4" if size==6 else "LS47"))
eprint('ALPHABET : ' + letters)
if szkeyword:
eprint('KEYWORD : ' + szkeyword)
eprint('KEY : ' + initialkey) # key variable modified during process?
eprint('NONCE : ' + nonce)
eprint('NONCE ENC : ' + nonce_enc)
eprint('NONCEMODE : ' + ("Kaminsky" if nonce_mode==1 else "Kratochvil"))
eprint('MARKER : ' + ("Kaminsky" if marker_mode==1 else "Kratochvil"))
if enc:
# if args.signature: print ("args.SIGNA:", args.signature)
if szsignature: print ("SIGNATURE: ", szsignature)
eprint('PLAINTEXT : ' + plaintext)
eprint('CIPHERTEXT: ' + ciphertext)
else:
eprint('CIPHERTEXT: ' + ciphertext)
eprint('PLAINTEXT : ' + plaintext)
def test1(size, fixednonce):
# Declaration "global" only needed if you like to write to a global variable
# [here, this is necessary only if the global var. is used within a fct. called by test1()]
# As test1() is called several times don't change args components within this fct.
global letters, nonce_mode, marker_mode, tiles, noncelen, nonce, nonce_size, nonce_enc
global ciphertext, plaintext, key, initialkey, mp
global szkeyword, szsignature
if size == 7:
CIPHERNAME = "LS47"
letters = letters7
nonce_mode = 2
marker_mode = 2
if fixednonce == 0:
noncelen=10; nonce = create_random_nonce(noncelen)
else:
nonce = 'dr0+:_pij2' # just a sample for testing fixed nonce
else:
CIPHERNAME = "LC4"
letters = letters6
nonce_mode = 1
marker_mode = 1
if fixednonce == 0:
noncelen=6; nonce = create_random_nonce(noncelen)
else:
nonce = 'pjpm5i' # just a sample for testing fixed nonce
tiles = list(zip(letters, [(x // size, x % size) for x in range(size * size)]))
check_nonce(nonce)
nonce_size = len(nonce)
nonce_enc = ""
print('\n' + CIPHERNAME)
if size == 7:
if args.keywordstring:
keyword = args.keywordstring # Allows to use -ws besides -t
else:
keyword = 's3cret_p4ssw0rd/31337'
szkeyword = keyword # This statement needed to show keyword in printinfo() [don't change args.keywordstring within test1()!]
key = derive_key(keyword, false)
else:
key = letters
initialkey = key
check_key(key)
mp = (0, 0)
if size == 7:
# signature = 'peace-vector-3' # just to name a meaningful value for size=7
plaintext = 'conflagrate_the_rose_bush_at_six!'
if szsignature: plaintext += szsignature
else:
# signature = '#its_me' # Notice: with size=6 the chars "#", "0", "1", "-" aren't part of the alphabet
plaintext = 'its_my_fathers_son_but_not_my_brother'
if szsignature: plaintext += szsignature
check_plaintext(plaintext)
ciphertext = encrypt_with_nonce(plaintext)
key = initialkey; mp = (0, 0) # initialization again
check_ciphertext(ciphertext)
decryptedtext = decrypt_with_nonce(ciphertext)
print('decrypted text: ' + decryptedtext)
printinfo(True) # Called from test1() with arg TRUE = assume to do decryption
szkeyword=''
if __name__ == '__main__':
parser = argparse.ArgumentParser() # how to enforce, that (either no arg), (or only one arg -t, -v), (or give key and enc mode)
parser.add_argument("-v", "--verbose", help="output additional information on stderr", action="count", default=0)
mgroup1 = parser.add_mutually_exclusive_group()
mgroup1.add_argument("-6", "--lc4", help="use ElsieFour cipher (6x6 table) (default)", action="store_true")
mgroup1.add_argument("-7", "--ls47", help="use LS47 cipher (7x7 table)", action="store_true")
parser.add_argument("-pc", "--playingcard", help="Use the \"playing card\" character tables (default: standard tables)", action="store_true")
mgroup2 = parser.add_mutually_exclusive_group()
mgroup2.add_argument("-ks", "--keystring", metavar="STRING", help="use STRING as key")
mgroup2.add_argument("-kf", "--keyfile", metavar="FILE", help="read key from FILE")
mgroup2.add_argument("-ws", "--keywordstring", metavar="STRING", help="generate key from keyword STRING", default=None)
mgroup2.add_argument("-wf", "--keywordfile", metavar="FILE", help="read keyword from FILE to generate key", default=None)
mgroup4 = parser.add_mutually_exclusive_group()
mgroup4.add_argument("-es", "--encryptstring", metavar="STRING", help="encrypt STRING")
mgroup4.add_argument("-ef", "--encryptfile", metavar="FILE", help="read plaintext from FILE and encrypt it")
mgroup4.add_argument("-ds", "--decryptstring", metavar="STRING", help="decrypt STRING")
mgroup4.add_argument("-df", "--decryptfile", metavar="FILE", help="read ciphertext from FILE and decrypt it")
mgroup4.add_argument("-t", "--test", help="encrypt and decrypt a string with a given key (with LC4, the given key equals the alphabet). Four cases tested: random/fixed nonce, each with LC4 and LS47", action="store_true")
mgroup3 = parser.add_mutually_exclusive_group()
mgroup3.add_argument("-nl", "--noncelen", metavar="LENGTH", help="use random nonce of length LENGTH (default: no nonce)", type=int, default=0)
mgroup3.add_argument("-ns", "--noncestring", metavar="STRING", help="use STRING as nonce (default: no nonce)")
mgroup5 = parser.add_mutually_exclusive_group()
mgroup5.add_argument("-n0", "--nKaminsky", help="use nonce in Kaminsky mode (default for LC4)", action="store_true")
mgroup5.add_argument("-n1", "--nKratochvil", help="use nonce in Kratochvil mode (default for LS47)", action="store_true")
mgroup6 = parser.add_mutually_exclusive_group()
mgroup6.add_argument("-m0", "--mKaminsky", help="use marker in Kaminsky mode (default for LC4)", action="store_true")
mgroup6.add_argument("-m1", "--mKratochvil", help="use marker in Kratochvil mode (default for LS47)", action="store_true")
parser.add_argument("-s", "--signature", help="append SIGNATURE to plaintext when encrypting (default: no signature)")
args = parser.parse_args()
if len(sys.argv)==1:
parser.print_help()
sys.exit(1)
if args.verbose and len(sys.argv)==2:
print('Version: ' + version)
# parser.print_help()
sys.exit(1)
# set cipher
if args.ls47:
size = 7
if args.playingcard:
letters = letters7card
else:
letters = letters7
else:
size = 6
if args.playingcard:
letters = letters6card
else:
letters = letters6
tiles = list(zip(letters, [(x // size, x % size) for x in range(size * size)]))
# set nonce
if args.noncestring:
nonce = args.noncestring
elif args.noncelen:
nonce = create_random_nonce(args.noncelen)
else:
nonce = ""
check_nonce(nonce)
nonce_size = len(nonce)
nonce_enc = ""
# set nonce mode
nonce_mode = 1 if size==6 else 2
if args.nKaminsky: nonce_mode = 1
if args.nKratochvil: nonce_mode = 2
# set marker mode
marker_mode = 1 if size==6 else 2
if args.mKaminsky: marker_mode = 1
if args.mKratochvil: marker_mode = 2
# set key
key = letters
# helper variables for verbose printing via printinfo()
szkeyword = '' # global variable which can be changed in test1() [so it can be used as test condition in printinfo() instead of args.keywordstring and instead of test1() manipulating args.keywordstring]
szsignature = '' # global variable which can be changed in test1() [so it can be used as test condition in printinfo() instead of args.keywordstring and instead of test1() manipulating args.keywordstring]. # Allows to use -s besides -t
if args.signature: # This case here is only necessary if -s should be used together with -t
szsignature = args.signature
if args.keywordfile: args.keywordstring = open(args.keywordfile, 'r').read().rstrip('\r\n')
if args.keywordstring:
szkeyword = args.keywordstring
key = derive_key(args.keywordstring, args.playingcard)
if args.keyfile: args.keystring = open(args.keyfile, 'r').read().rstrip('\r\n')
if args.keystring: key = args.keystring;
initialkey = key
check_key(key)
mp = (0, 0)
# encrypt / decrypt / test
if args.encryptfile:
args.encryptstring = open(args.encryptfile, 'r').read().rstrip('\r\n')
if args.decryptfile:
args.decryptstring = open(args.decryptfile, 'r').read().rstrip('\r\n')
if args.encryptstring:
plaintext = args.encryptstring
if args.signature:
plaintext += args.signature
check_plaintext(plaintext)
ciphertext = encrypt_with_nonce(plaintext)
if args.verbose:
printinfo(True)
else:
print(ciphertext)
elif args.decryptstring:
ciphertext = args.decryptstring
check_ciphertext(ciphertext)
plaintext = decrypt_with_nonce(ciphertext)
if args.signature and args.verbose:
eprint("--Warning--: the given signature is ignored during decryption")
# Maybe later return result of a check whether given signature equals the end of the decrypted string.
if args.verbose:
printinfo()
else:
print(plaintext)
elif args.test:
print('\nVersion: ' + version)
print('\n---Test: No nonce provided (only its length), so each call will produce a different ciphertext.')
size = 7; test1(size, 0)
size = 6; test1(size, 0)
print('\n---Test: Nonce provided as string.')
size = 7; test1(size, 1)
size = 6; test1(size, 1)
sys.exit(1)
else: # you'll never get here (handled via argparse)
# if args.verbose: print('Version : ' + version)
print('ALPHABET : ' + letters)
print('KEY : ' + initialkey)
print('NONCE : ' + nonce)
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