Add a human usuable binary with ElsieFour and LS47
This commit is contained in:
Bernard Esslinger
parent
98f02f2cbd
commit
a33aa2a04b
402
lc4.py
Executable file
402
lc4.py
Executable file
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#!/usr/bin/python2
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# -*- coding: utf-8 -*-
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# This software is hereby released into public domain. Use it wisely.
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#
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# ElsieFour (LC4) and its enhancement LS47
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# version 2.7: 2018-02-13
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#
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# - Python script for LS47 originally written by Mirek Kratochvil (2017)
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# See https://github.com/exaexa/ls47
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# - Python 3 port by Bernhard Esslinger / AK (Feb 2018)
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# See www.mysterytwisterc3.org
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# - New options by CrypTool project (www.cryptool.org) (Feb 2018) in order to
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# support both ciphers LC4 and LS47, both ways to deal with nonces, keyword
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# usage for both LC4 and LS47, reading from file and commandline, and
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# extended test outputs.
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#
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# Sample calls:
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# - Using cipher LC4, enforced with option -6:
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# python lc4-ls47.py -6 -ws thisismysecretkey -es its_my_fathers_son_but_not_my_brother -v -nl 6
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# python lc4-ls47.py -6 -ws thisismysecretkey -ds q6xojffkncfyz#f5czs49#3mbsco#2iscvbnm#bymaf -v -nl 6
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# - Using cipher LS47, enforced with option -7:
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# python lc4-ls47.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
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# python lc4-ls47.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'
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#
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from __future__ import print_function
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import sys
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import os
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import random
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import argparse
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version = "v2.7 (2018-02-13)"
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letters6 = "#_23456789abcdefghijklmnopqrstuvwxyz"
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letters7 = "_abcdefghijklmnopqrstuvwxyz.0123456789,-+*/:?!'()"
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def missing_letters(s,t):
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return ''.join(sorted(set(c for c in s if c not in t)))
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def check_key(key):
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illegal = missing_letters(key,letters)
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missing = missing_letters(letters,key)
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duplicates = ''.join(sorted(c for c in letters if key.count(c)>1))
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errors = []
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if illegal: errors.append( "Key contains illegal letters: '%s'" % illegal )
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if missing: errors.append( "Key misses some letters: '%s'" % missing )
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if duplicates: errors.append( "Key contains duplicate letters: '%s'" % duplicates )
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if errors:
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errors.append( "The key must be a permutation of the alphabet: %s" % letters )
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raise ValueError("\n".join(errors))
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def check_nonce(nonce):
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illegal = missing_letters(nonce,letters)
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if illegal:
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raise ValueError("Nonce contains illegal letters: '%s'" % illegal)
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def check_plaintext(s):
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illegal = missing_letters(s,letters)
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if illegal:
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raise ValueError("Plaintext contains illegal letters: '%s'" % illegal)
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def check_ciphertext(s):
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illegal = missing_letters(s,letters)
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if illegal:
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raise ValueError("Ciphertext contains illegal letters: '%s'" % illegal)
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def find_ix(letter):
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m = [l[1] for l in tiles if l[0] == letter]
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if len(m) != 1:
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raise ValueError("Letter '%c' not in the alphabet!" % letter)
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return m[0]
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def find_pos(key, letter):
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p = key.find(letter)
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if not (0 <= p < size * size):
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raise ValueError("Letter '%c' not in key?!" % letter)
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return (p // size, p % size)
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def add_pos(a, b):
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return ((a[0] + b[0]) % size, (a[1] + b[1]) % size)
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def sub_pos(a, b):
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return ((a[0] - b[0]) % size, (a[1] - b[1]) % size)
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def find_at_pos(key, coord):
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return key[coord[1] + coord[0] * size]
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def rotate_right(key, row, n):
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mid = key[size * row:size * (row + 1)]
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return key[:size * row] + mid[-n:] + mid[:-n] + key[size * (row + 1):]
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def rotate_down(key, col, n):
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lines = [key[i * size:(i + 1) * size] for i in range(size)]
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lefts = [l[:col] for l in lines]
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mids = [l[col] for l in lines]
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rights = [l[col + 1:] for l in lines]
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mids = mids[-n:] + mids[:-n]
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return ''.join(lefts[i] + mids[i] + rights[i] for i in range(size))
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def rotate_marker_right(m, row, n):
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if m[0] != row:
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return (m[0], m[1])
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else:
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return (m[0], (m[1] + n) % size)
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def rotate_marker_down(m, col, n):
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if m[1] != col:
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return (m[0], m[1])
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else:
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return ((m[0] + n) % size, m[1])
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def derive_key(password):
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i = 0
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k = letters
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for c in password:
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(row, col) = find_ix(c)
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k = rotate_down(rotate_right(k, i, col), i, row)
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i = (i + 1) % size
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return k
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def encrypt(plaintext):
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global key, mp
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ciphertext = ''
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for p in plaintext:
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pp = find_pos(key, p)
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mix = find_ix(find_at_pos(key, mp))
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cp = add_pos(pp, mix)
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c = find_at_pos(key, cp)
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ciphertext += c
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key = rotate_right(key, pp[0], 1)
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mp = rotate_marker_right(mp, pp[0], 1)
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cp = find_pos(key, c)
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key = rotate_down(key, cp[1], 1)
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mp = rotate_marker_down(mp, cp[1], 1)
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mp = add_pos(mp, find_ix(c))
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return ciphertext
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def decrypt(ciphertext):
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global key, mp
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plaintext = ''
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for c in ciphertext:
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cp = find_pos(key, c)
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mix = find_ix(find_at_pos(key, mp))
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pp = sub_pos(cp, mix)
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p = find_at_pos(key, pp)
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plaintext += p
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key = rotate_right(key, pp[0], 1)
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mp = rotate_marker_right(mp, pp[0], 1)
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cp = find_pos(key, c)
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key = rotate_down(key, cp[1], 1)
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mp = rotate_marker_down(mp, cp[1], 1)
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mp = add_pos(mp, find_ix(c))
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return plaintext
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def create_random_nonce(size):
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return ''.join(random.choice(letters) for i in range(size))
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def encrypt_with_nonce(plaintext):
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global nonce, nonce_enc
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ciphertext = encrypt(nonce + plaintext)
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nonce_enc = ciphertext[:nonce_size]
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if nonce_mode==1:
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return nonce + ciphertext[nonce_size:]
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else:
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return ciphertext
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def decrypt_with_nonce(ciphertext):
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global nonce, nonce_enc
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if nonce_mode==1:
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nonce = ciphertext[:nonce_size]
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nonce_enc = encrypt(nonce)
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return decrypt(ciphertext[nonce_size:])
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else:
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plaintext = decrypt(ciphertext)
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nonce = plaintext[:nonce_size]
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nonce_enc = ciphertext[:nonce_size]
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return plaintext[nonce_size:]
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def eprint(*args, **kwargs):
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print(*args, file=sys.stderr, **kwargs)
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def printinfo(enc=False):
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eprint('CIPHER : ' + ("LC4" if size==6 else "LS47"))
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eprint('ALPHABET : ' + letters)
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if args.keywordstring:
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eprint('KEYWORD : ' + args.keywordstring)
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eprint('KEY : ' + initialkey) # key variable modified during process?
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eprint('NONCE : ' + nonce)
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eprint('NONCE ENC : ' + nonce_enc)
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eprint('NONCEMODE : ' + ("Kaminsky" if nonce_mode==1 else "Kratochvil"))
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if enc:
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eprint('PLAINTEXT : ' + plaintext)
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eprint('CIPHERTEXT: ' + ciphertext)
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else:
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eprint('CIPHERTEXT: ' + ciphertext)
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eprint('PLAINTEXT : ' + plaintext)
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def test1(size):
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global letters, nonce_mode, tiles, noncelen, nonce, nonce_size, nonce_enc, signature
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global ciphertext, plaintext, key, initialkey, mp
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if size == 7:
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CIPHERNAME = "LS47"
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letters = letters7;
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nonce_mode = 2
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noncelen=10; nonce = create_random_nonce(noncelen)
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# nonce = 'dr0+:_pij2' # just a sample for testing fixed nonce
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else:
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CIPHERNAME = "LC4"
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letters = letters6;
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nonce_mode = 1
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noncelen=6; nonce = create_random_nonce(noncelen)
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# nonce = 'pjpm5i' # just a sample for testing fixed nonce
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tiles = list(zip(letters, [(x // size, x % size) for x in range(size * size)]))
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check_nonce(nonce)
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nonce_size = len(nonce)
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nonce_enc = ""
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print('\n' + CIPHERNAME)
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if size == 7:
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keyword = 's3cret_p4ssw0rd/31337'; args.keywordstring=keyword
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key = derive_key(keyword)
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else:
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key = letters
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initialkey = key
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check_key(key)
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mp = (0, 0)
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if size == 7:
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plaintext = 'conflagrate_the_rose_bush_at_six!'
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signature = 'peace-vector-3'
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else:
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plaintext = 'its_my_fathers_son_but_not_my_brother'
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signature = '#its_me' # signature = ''
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check_plaintext(plaintext)
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ciphertext = encrypt_with_nonce(plaintext)
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key = initialkey; mp = (0, 0) # initialization again
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check_ciphertext(ciphertext)
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decryptedtext = decrypt_with_nonce(ciphertext)
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print('decrypted text: ' + decryptedtext)
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printinfo(True)
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args.keywordstring=''
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if __name__ == '__main__':
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parser = argparse.ArgumentParser()
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mgroup = parser.add_mutually_exclusive_group()
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parser.add_argument("-v", "--verbose", help="output additional information on stderr", action="count", default=0)
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mgroup.add_argument("-6", "--lc4", help="use ElsieFour cipher (6x6 table) (default)", action="store_true")
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mgroup.add_argument("-7", "--ls47", help="use LS47 cipher (7x7 table)", action="store_true")
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mgroup2 = parser.add_mutually_exclusive_group()
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mgroup2.add_argument("-ks", "--keystring", metavar="STRING", help="use STRING as key")
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mgroup2.add_argument("-kf", "--keyfile", metavar="FILE", help="read key from FILE")
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mgroup2.add_argument("-ws", "--keywordstring", metavar="STRING", help="generate key from keyword STRING", default=None)
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mgroup2.add_argument("-wf", "--keywordfile", metavar="FILE", help="read keyword from FILE to generate key", default=None)
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mgroup3 = parser.add_mutually_exclusive_group()
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mgroup3.add_argument("-nl", "--noncelen", metavar="LENGTH", help="use random nonce of length LENGTH", type=int, default=0)
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mgroup3.add_argument("-ns", "--noncestring", metavar="STRING", help="use STRING as nonce")
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parser.add_argument("-n0", "--nKaminsky", help="use nonce in Kaminsky mode (default for LC4)", action="store_true")
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parser.add_argument("-n1", "--nKratochvil", help="use nonce in Kratochvil mode (default for LS47)", action="store_true")
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mgroup4 = parser.add_mutually_exclusive_group()
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mgroup4.add_argument("-es", "--encryptstring", metavar="STRING", help="encrypt STRING")
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mgroup4.add_argument("-ef", "--encryptfile", metavar="FILE", help="read plaintext from FILE and encrypt it")
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mgroup4.add_argument("-ds", "--decryptstring", metavar="STRING", help="decrypt STRING")
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mgroup4.add_argument("-df", "--decryptfile", metavar="FILE", help="read ciphertext from FILE and decrypt it")
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mgroup4.add_argument("-t", "--test", help="encrypt and decrypt a string with a random nonce and a given key (once with LC4 and once with LS47)", action="store_true")
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parser.add_argument("-s", "--signature", help="append SIGNATURE to plaintext when encrypting")
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args = parser.parse_args()
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if len(sys.argv)==1:
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parser.print_help()
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sys.exit(1)
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if args.verbose and len(sys.argv)==2:
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print('Version: ' + version)
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# parser.print_help()
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sys.exit(1)
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# set cipher
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if args.ls47:
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size = 7
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letters = letters7
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else:
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size = 6
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letters = letters6
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tiles = list(zip(letters, [(x // size, x % size) for x in range(size * size)]))
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# set nonce
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if args.noncestring:
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nonce = args.noncestring
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elif args.noncelen:
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nonce = create_random_nonce(args.noncelen)
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else:
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nonce = ""
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check_nonce(nonce)
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nonce_size = len(nonce)
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nonce_enc = ""
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# set nonce mode
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nonce_mode = 1 if size==6 else 2
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if args.nKaminsky: nonce_mode = 1
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if args.nKratochvil: nonce_mode = 2
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# set key
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key = letters
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if args.keywordfile: args.keywordstring = open(args.keywordfile, 'r').read().rstrip('\r\n')
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if args.keywordstring: key = derive_key(args.keywordstring);
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if args.keyfile: args.keystring = open(args.keyfile, 'r').read().rstrip('\r\n')
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if args.keystring: key = args.keystring;
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initialkey = key
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check_key(key)
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mp = (0, 0)
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# encrypt / decrypt / test
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if args.encryptfile:
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args.encryptstring = open(args.encryptfile, 'r').read().rstrip('\r\n')
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if args.decryptfile:
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args.decryptstring = open(args.decryptfile, 'r').read().rstrip('\r\n')
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if args.encryptstring:
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plaintext = args.encryptstring
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if args.signature: plaintext += args.signature
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check_plaintext(plaintext)
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ciphertext = encrypt_with_nonce(plaintext)
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if args.verbose: printinfo(True)
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print(ciphertext)
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elif args.decryptstring:
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ciphertext = args.decryptstring
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check_ciphertext(ciphertext)
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plaintext = decrypt_with_nonce(ciphertext)
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if args.verbose: printinfo()
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if args.signature and args.verbose:
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eprint("Warning: the given signature is ignored during decryption")
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print(plaintext)
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elif args.test:
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print('\nVersion: ' + version)
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print('Test: No nonce provided (only its length), so each call will produce a different ciphertext.')
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size = 7; test1(size)
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size = 6; test1(size)
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sys.exit(1)
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else:
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# if args.verbose: print('Version : ' + version)
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print('ALPHABET : ' + letters)
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print('KEY : ' + initialkey)
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print('NONCE : ' + nonce)
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