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1 #!/usr/bin/env python3 |
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2 """Create a passphrase from a few random words. DRAFT |
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3 |
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4 Relies on the entropy of python's |
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5 random.SystemRandom class |
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6 which (according to the documentation) calls os.urandom() |
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7 which (according to the documentation) calls the operating system |
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8 specific randomness source which "should be unpredictable |
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9 enough for cryptographic applications" |
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10 |
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11 Requires: |
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12 * Python v>=3.2 |
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13 * a dictionary, Ding's trans-de-en by default. |
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14 E.g. on a Debian/Ubuntu system in package "trans-de-en". |
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15 or from http://ftp.tu-chemnitz.de/pub/Local/urz/ding/de-en/ |
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16 |
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17 Uses a hardcodes filepath and selected language. |
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18 Search for **customize** below to change it. |
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19 |
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20 Copyright 2016 by Intevation GmbH. |
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21 Author: 2016-01-21 Bernhard E. Reiter <bernhard@intevation.de> |
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22 |
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23 This file is Free Software under the Apache 2.0 license and thus |
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24 comes without any warranty (to extend permissible under applicable law). |
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25 """ |
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26 |
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27 import math |
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28 import re |
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29 import sys |
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30 |
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31 from random import SystemRandom |
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32 _srandom = SystemRandom() |
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33 |
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34 tainted = False # to be set if we find a hint that the passphrase may be weak |
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35 |
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36 def buildDictionary(): |
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37 """Build up a dictionary of unique words, calculate stats.""" |
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38 global tainted |
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39 d = [] |
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40 |
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41 # dictionary for testing |
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42 #d = ["abc", "aBc", "cde", "efg", "hij", "blubber", "jikf", "zug", "lmf", "opq"] |
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43 |
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44 # Using the dictionary from Ding **customize** |
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45 d = readDingDict(filename="/usr/share/trans/de-en", useLeft=True) |
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46 |
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47 ## for debugging purpuses, dump dictionary |
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48 #dumpfilename = "ddump.txt" |
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49 #print("Writing out {}.".format(dumpfilename)) |
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50 #with open(dumpfilename, "w") as f: |
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51 # for i in d: |
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52 # f.write("{}\n".format(i)) |
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53 |
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54 # Print some stats on the dictionary to be used |
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55 dl = len(d) |
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56 print("Found {:d} dictionary entries".format(dl)) |
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57 if dl < 2000: |
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58 print("!Your dictionary is below 2k entries, that is quite small!") |
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59 tainted = True |
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60 |
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61 print("|= Number of words |= possibilities |") |
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62 for i in range(1,5): |
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63 print("| {:2d} | 2^{:4.1f} |".format( |
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64 i, math.log(dl**i,2))) |
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65 return d |
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66 |
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67 |
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68 def readDingDict(filename = "/usr/share/trans/de-en", useLeft=False): |
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69 """Read dictionary with unique words from file in Ding format. |
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70 |
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71 useLeft: Boolean to control which language to use |
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72 |
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73 TODO: add option to use both languages for people that speak them both? |
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74 """ |
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75 |
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76 dset = set() #using the datatype 'set' to aviod duplicates |
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77 |
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78 splitter = re.compile(r"""\ \|\ # first pattern ' | ' |
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79 |;\ # second pattern '; ' |
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80 |(?<=\S)/(?=\S) # 3.: '\' surrounded by chars |
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81 |\s+ # by whitespace |
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82 """,re.VERBOSE) |
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83 |
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84 print("Reading entries from {}.".format(filename), end='') |
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85 counter = 0 # for progress or stopping early |
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86 with open(filename, "r") as f: |
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87 for line in f: |
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88 if line[0] == '#': continue |
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89 |
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90 # languages are separated by " :: " |
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91 p = line.partition(" :: ") |
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92 languageEntry = p[0] if useLeft else p[2] |
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93 |
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94 for word in splitter.split(languageEntry): |
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95 word = word.strip('(",.)\'!:;').rstrip('/') |
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96 if len(word) > 2 and not word[0] in '[{/': |
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97 dset.add(word) |
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98 |
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99 #TODO: check for very common words and remove them? |
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100 |
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101 counter += 1 |
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102 ## stop early when debugging |
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103 #if counter > 10: break |
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104 if not counter % 10000: |
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105 print('.', end='') |
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106 sys.stdout.flush() |
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107 print() |
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108 |
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109 return list(dset) |
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110 |
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111 def main(): |
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112 global tainted |
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113 dictionary = buildDictionary() |
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114 |
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115 howMany = 4 |
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116 |
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117 # use a dictionary with lower case words for a simple check if |
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118 # our random source is okay |
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119 print("\nGenerated passphrase with {} randomly selected words:\n".format( |
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120 howMany)) |
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121 print(" ", end='') |
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122 words = {} |
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123 for x in range(howMany): |
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124 word = _srandom.choice(dictionary) |
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125 words[word.lower]= True |
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126 print(word, end='\n ') |
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127 print("\n") |
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128 |
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129 if len(words) < howMany: |
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130 print("! Your random generator is weak") |
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131 print("! or you are being very lucky.") |
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132 tainted = True |
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133 |
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134 if tainted: |
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135 print("!!! Don't use the resulting passphrase !!!") |
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136 |
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137 if __name__ == "__main__": |
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138 main() |
