Mercurial > ppgen
annotate ppgen.py @ 8:200c2c3c5f67
Adds comfort.
* Adds options
** '--just-passphrase': to get a passphrase on one line for use in skripts.
** '--number-of-words': the passphrase shall consists of
* Refactors to implement the options and preparing for future developments:
** Warnings will be written to stderr and tained will bail out with sys.exit().
** The output_string is build before printing.
| author | Bernhard Reiter <bernhard@intevation.de> |
|---|---|
| date | Thu, 18 Jan 2018 08:44:33 +0100 |
| parents | 8b2f8f439817 |
| children | 35c468a37b54 |
| rev | line source |
|---|---|
| 0 | 1 #!/usr/bin/env python3 |
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2 """Create a random passphrase from a dictionary of words. BETA |
| 0 | 3 |
| 4 Relies on the entropy of python's | |
| 5 random.SystemRandom class | |
| 6 which (according to the documentation) calls os.urandom() | |
| 7 which (according to the documentation) calls the operating system | |
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8 specific randomness source which "should be unpredictable |
| 0 | 9 enough for cryptographic applications" |
| 10 | |
| 11 Requires: | |
| 12 * Python v>=3.2 | |
| 13 * a dictionary, Ding's trans-de-en by default. | |
| 14 E.g. on a Debian/Ubuntu system in package "trans-de-en". | |
| 15 or from http://ftp.tu-chemnitz.de/pub/Local/urz/ding/de-en/ | |
| 16 | |
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17 Uses a hardcoded filepath and language. |
| 0 | 18 Search for **customize** below to change it. |
| 19 | |
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20 Related: There is a Go implementation started by Sascha L. Teichmann at |
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21 https://bitbucket.org/s_l_teichmann/ppgen |
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22 |
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23 |
| 8 | 24 Copyright 2016, 2017, 2018 by Intevation GmbH. |
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25 Author: Bernhard E. Reiter <bernhard@intevation.de> |
| 0 | 26 |
| 27 This file is Free Software under the Apache 2.0 license and thus | |
| 28 comes without any warranty (to extend permissible under applicable law). | |
| 29 """ | |
| 30 | |
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31 import argparse |
| 0 | 32 import math |
| 33 import re | |
| 34 import sys | |
| 35 | |
| 36 from random import SystemRandom | |
| 37 _srandom = SystemRandom() | |
| 38 | |
| 39 tainted = False # to be set if we find a hint that the passphrase may be weak | |
| 40 | |
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41 |
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42 def buildDictionary(options): |
| 0 | 43 """Build up a dictionary of unique words, calculate stats.""" |
| 44 global tainted | |
| 45 d = [] | |
| 46 | |
| 47 # dictionary for testing | |
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48 #d = ["abc", "aBc", "cde", "efg", "hij", "blubber", |
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49 # "jikf", "zug", "lmf", "opq"] |
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50 # second test dictionary to show that different string functions are used. |
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51 #d = [''.join('A' * 1000) for _ in range(1000)] |
| 0 | 52 |
| 53 # Using the dictionary from Ding **customize** | |
| 8 | 54 d = readDingDict(options, filename="/usr/share/trans/de-en", useLeft=True) |
| 0 | 55 |
| 8 | 56 # for debugging purposes, dump dictionary |
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57 if options.ddump_filename: |
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58 print("Writing out dictionary in '{}'.".format(options.ddump_filename)) |
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59 with open(options.ddump_filename, "w") as f: |
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60 for i in d: |
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61 f.write("{}\n".format(i)) |
| 0 | 62 |
| 63 # Print some stats on the dictionary to be used | |
| 64 dl = len(d) | |
| 8 | 65 if not options.just_passphrase: |
| 66 print("Found {:d} dictionary entries.".format(dl)) | |
| 67 print("|= Number of words |= possibilities |") | |
| 68 for i in range(1, 5): | |
| 69 print("| {:2d} | 2^{:4.1f} |".format( | |
| 70 i, math.log(dl**i, 2))) | |
| 71 | |
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72 if dl < 8000: |
| 8 | 73 sys.stderr.write("!Your dictionary is below 8k entries, " |
| 74 "that is quite small!\n") | |
| 0 | 75 tainted = True |
| 76 return d | |
| 77 | |
| 78 | |
| 8 | 79 def readDingDict(options, filename="/usr/share/trans/de-en", useLeft=False): |
| 0 | 80 """Read dictionary with unique words from file in Ding format. |
| 81 | |
| 82 useLeft: Boolean to control which language to use | |
| 83 | |
| 84 TODO: add option to use both languages for people that speak them both? | |
| 85 """ | |
| 86 | |
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87 dset = set() # using the datatype 'set' to avoid duplicates |
| 0 | 88 |
| 89 splitter = re.compile(r"""\ \|\ # first pattern ' | ' | |
| 90 |;\ # second pattern '; ' | |
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91 |(?<=\S)/(?=\S) # 3.: '/' surrounded by chars |
| 0 | 92 |\s+ # by whitespace |
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93 """, re.VERBOSE) |
| 0 | 94 |
| 8 | 95 if not options.just_passphrase: |
| 96 print("Reading entries from {}.".format(filename), end='') | |
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97 counter = 0 # for progress or stopping early |
| 0 | 98 with open(filename, "r") as f: |
| 99 for line in f: | |
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100 if line[0] == '#': |
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101 continue |
| 0 | 102 |
| 103 # languages are separated by " :: " | |
| 104 p = line.partition(" :: ") | |
| 105 languageEntry = p[0] if useLeft else p[2] | |
| 106 | |
| 107 for word in splitter.split(languageEntry): | |
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108 word = word.strip('(",.)\'!:;<>').rstrip('/') |
| 0 | 109 if len(word) > 2 and not word[0] in '[{/': |
| 110 dset.add(word) | |
| 111 | |
| 112 #TODO: check for very common words and remove them? | |
| 113 | |
| 114 counter += 1 | |
| 115 ## stop early when debugging | |
| 116 #if counter > 10: break | |
| 8 | 117 if not options.just_passphrase and counter % 10000 == 0: |
| 0 | 118 print('.', end='') |
| 119 sys.stdout.flush() | |
| 8 | 120 if not options.just_passphrase: |
| 121 print() | |
| 0 | 122 |
| 123 return list(dset) | |
| 124 | |
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125 |
| 0 | 126 def main(): |
| 127 global tainted | |
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128 |
| 8 | 129 parser = argparse.ArgumentParser( |
| 130 description=__doc__.splitlines()[0], | |
| 131 formatter_class=argparse.ArgumentDefaultsHelpFormatter) | |
| 132 parser.add_argument('-n', '--number-of-words', type=int, default=4, | |
| 133 help='how many words to draw for the passphrase, ' | |
| 134 'most useful with -j') | |
| 135 parser.add_argument('-j', '--just-passphrase', action="store_true", | |
| 136 help='only output the passphrase on a single line') | |
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137 parser.add_argument('--ddump-filename', |
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138 help='filename to dump the dictionary to') |
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139 options = parser.parse_args() |
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140 |
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141 dictionary = buildDictionary(options) |
| 0 | 142 |
| 8 | 143 how_many = options.number_of_words |
| 0 | 144 |
| 8 | 145 output_string = "" |
| 146 if not options.just_passphrase: | |
| 147 print("\nGenerated passphrase with {}" | |
| 148 " randomly selected words:\n".format(how_many)) | |
| 149 print(" ", end='') | |
| 150 separator = '\n ' | |
| 151 else: | |
| 152 separator = ' ' | |
| 153 | |
| 154 # use a dictionary `words` with lower cased words for a rudimentary check | |
| 0 | 155 words = {} |
| 8 | 156 for x in range(how_many): |
| 0 | 157 word = _srandom.choice(dictionary) |
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158 words[word.lower()] = True |
| 8 | 159 output_string += word + separator |
| 0 | 160 |
| 8 | 161 print(output_string) |
| 162 | |
| 163 if len(words) < how_many: | |
| 164 sys.stderr.write("! You've drawn a word more than once, this means:\n" | |
| 165 "! Your random generation is weak" | |
| 166 " or you are being very lucky.\n") | |
| 0 | 167 tainted = True |
| 168 | |
| 169 if tainted: | |
| 8 | 170 sys.exit("!!! Don't use the resulting passphrase !!!") |
| 0 | 171 |
| 172 if __name__ == "__main__": | |
| 173 main() |