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# Provides support generating memorable passwords |
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class PasswordGenerator |
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private |
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# This flag is used in conjunction with Password.generate and states that a |
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# password must include a digit. |
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ONE_DIGIT = 1 |
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# This flag is used in conjunction with Password.generate and states that a |
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# password must include a capital letter. |
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ONE_CASE = 1 << 1 |
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# Phoneme flags |
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CONSONANT = 1 |
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VOWEL = 1 << 1 |
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DIPHTHONG = 1 << 2 |
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NOT_FIRST = 1 << 3 # Indicates that a given phoneme may not occur first |
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PHONEMES = { |
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:a => VOWEL, |
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:ae => VOWEL | DIPHTHONG, |
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:ah => VOWEL | DIPHTHONG, |
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:ai => VOWEL | DIPHTHONG, |
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:b => CONSONANT, |
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:c => CONSONANT, |
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:ch => CONSONANT | DIPHTHONG, |
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:d => CONSONANT, |
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:e => VOWEL, |
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:ee => VOWEL | DIPHTHONG, |
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:ei => VOWEL | DIPHTHONG, |
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:f => CONSONANT, |
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:g => CONSONANT, |
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:gh => CONSONANT | DIPHTHONG | NOT_FIRST, |
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:h => CONSONANT, |
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:i => VOWEL, |
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:ie => VOWEL | DIPHTHONG, |
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:j => CONSONANT, |
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:k => CONSONANT, |
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:l => CONSONANT, |
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:m => CONSONANT, |
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:n => CONSONANT, |
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:ng => CONSONANT | DIPHTHONG | NOT_FIRST, |
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:o => VOWEL, |
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:oh => VOWEL | DIPHTHONG, |
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:oo => VOWEL | DIPHTHONG, |
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:p => CONSONANT, |
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:ph => CONSONANT | DIPHTHONG, |
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:qu => CONSONANT | DIPHTHONG, |
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:r => CONSONANT, |
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:s => CONSONANT, |
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:sh => CONSONANT | DIPHTHONG, |
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:t => CONSONANT, |
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:th => CONSONANT | DIPHTHONG, |
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:u => VOWEL, |
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:v => CONSONANT, |
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:w => CONSONANT, |
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:x => CONSONANT, |
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:y => CONSONANT, |
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:z => CONSONANT |
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} |
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class << self |
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# Determine whether the next character should be a vowel or consonant. |
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def get_vowel_or_consonant |
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rand(2) == 1 ? VOWEL : CONSONANT |
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end |
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# Generate a memorable password of +length+ characters, using phonemes that |
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# a human can easily remember. +flags+ is one or more of |
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# <tt>Password::ONE_DIGIT</tt> and <tt>Password::ONE_CASE</tt>, logically |
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# OR'ed together. For example: |
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# |
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# password = Password.generate(8, Password::ONE_DIGIT | Password::ONE_CASE) |
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# |
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# This would generate an eight character password, containing a digit and an |
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# upper-case letter, such as "Ug2shoth". |
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# |
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# This method was inspired by the pwgen[http://sourceforge.net/projects/pwgen] |
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# tool, written by Theodore Ts'o. |
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# |
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# Generated passwords may contain any of the characters in <tt>Password::PHONEMES</tt>. |
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def generate(length = 8, flags = nil) |
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password = nil |
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ph_flags = flags |
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loop do |
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password = '' |
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# Separate the flags integer into an array of individual flags |
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feature_flags = [flags & ONE_DIGIT, flags & ONE_CASE] |
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prev = [] |
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first = true |
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desired = self.get_vowel_or_consonant |
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# Get an Array of all of the phonemes |
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phonemes = PHONEMES.keys.map {|ph| ph.to_s} |
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nr_phonemes = phonemes.size |
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while password.length < length do |
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# Get a random phoneme and its length |
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phoneme = phonemes[rand(nr_phonemes)] |
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ph_len = phoneme.length |
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# Get its flags as an Array |
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ph_flags = PHONEMES[phoneme.to_sym] |
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ph_flags = [ph_flags & CONSONANT, ph_flags & VOWEL, ph_flags & DIPHTHONG, ph_flags & NOT_FIRST] |
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# Filter on the basic type of the next phoneme |
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next if ph_flags.include?(desired) |
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# Handle the NOT_FIRST flag |
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next if first && ph_flags.include?(NOT_FIRST) |
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# Don't allow a VOWEL followed a vowel/diphthong pair |
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next if prev.include?(VOWEL) && ph_flags.include?(VOWEL) && ph_flags.include?(DIPHTHONG) |
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# Don't allow us to go longer than the desired length |
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next if ph_len > (length - password.length) |
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# We've found a phoneme that meets our criteria |
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password << phoneme |
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# Handle ONE_CASE |
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if feature_flags.include?(ONE_CASE) |
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if (first || ph_flags.include?(CONSONANT)) && rand(10) < 3 |
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password[-ph_len, 1] = password[-ph_len, 1].upcase |
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feature_flags.delete(ONE_CASE) |
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end |
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end |
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# Is password already long enough? |
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break if password.length >= length |
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# Handle ONE_DIGIT |
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if feature_flags.include?(ONE_DIGIT) |
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if !first && rand(10) < 3 |
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password << (rand(10) + 48).chr |
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feature_flags.delete(ONE_DIGIT) |
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first = true |
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prev = [] |
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desired = PasswordGenerator.get_vowel_or_consonant |
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next |
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end |
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end |
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if desired == CONSONANT |
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desired = VOWEL |
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elsif prev.include?(VOWEL) || ph_flags.include?(DIPHTHONG) || rand(10) > 3 |
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desired = CONSONANT |
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else |
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desired = VOWEL |
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end |
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prev = ph_flags |
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first = false |
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end |
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# Try again |
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break unless feature_flags.include?(ONE_CASE) || feature_flags.include?(ONE_DIGIT) |
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end |
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password |
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end |
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end |
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end |
