Method: Password.phonemic

Defined in:

lib/password.rb

.phonemic(length = 8, flags = nil) ⇒ Object

Generate a memorable password of length characters, using phonemes that a human-being can easily remember. flags is one or more of Password::ONE_DIGIT and Password::ONE_CASE, logically OR’ed together. For example:

pw = Password.phonemic( 8, Password::ONE_DIGIT | Password::ONE_CASE )

This would generate an eight character password, containing a digit and an upper-case letter, such as Ug2shoth.

This method was inspired by the pwgen tool, written by Theodore Ts’o.

Generated passwords may contain any of the characters in Password::PASSWD_CHARS.

# File 'lib/password.rb', line 265

def Password.phonemic(length=8, flags=nil)

  pw = nil
  ph_flags = flags

  loop do

    pw = ""

    # Separate the flags integer into an array of individual flags
    feature_flags = [ flags & ONE_DIGIT, flags & ONE_CASE ]

    prev = []
    first = true
    desired = Password.get_vowel_or_consonant

    # Get an Array of all of the phonemes
    phonemes = PHONEMES.keys.map { |ph| ph.to_s }
    nr_phonemes = phonemes.size

    while pw.length < length do

	# Get a random phoneme and its length
	phoneme = phonemes[ rand( nr_phonemes ) ]
	ph_len = phoneme.length

	# Get its flags as an Array
	ph_flags = PHONEMES[ phoneme.to_sym ]
	ph_flags = [ ph_flags & CONSONANT, ph_flags & VOWEL,
     ph_flags & DIPHTHONG, ph_flags & NOT_FIRST ]

	# Filter on the basic type of the next phoneme
	next if ph_flags.include? desired

	# Handle the NOT_FIRST flag
	next if first and ph_flags.include? NOT_FIRST

	# Don't allow a VOWEL followed a vowel/diphthong pair
	next if prev.include? VOWEL and ph_flags.include? VOWEL and
ph_flags.include? DIPHTHONG

	# Don't allow us to go longer than the desired length
	next if ph_len > length - pw.length

	# We've found a phoneme that meets our criteria
	pw << phoneme

	# Handle ONE_CASE
	if feature_flags.include? ONE_CASE

 if (first or ph_flags.include? CONSONANT) and rand( 10 ) < 3
   pw[-ph_len, 1] = pw[-ph_len, 1].upcase
   feature_flags.delete ONE_CASE
 end

	end

	# Is password already long enough?
	break if pw.length >= length

	# Handle ONE_DIGIT
	if feature_flags.include? ONE_DIGIT

 if ! first and rand( 10 ) < 3
   pw << ( rand( 10 ) + ?0 ).chr
   feature_flags.delete ONE_DIGIT

   first = true
   prev = []
   desired = Password.get_vowel_or_consonant
   next
 end

	end

	if desired == CONSONANT
 desired = VOWEL
	elsif prev.include? VOWEL or ph_flags.include? DIPHTHONG or
     rand(10) > 3
 desired = CONSONANT
	else
 desired = VOWEL
	end

	prev = ph_flags
	first = false
    end

    # Try again
    break unless feature_flags.include? ONE_CASE or
   feature_flags.include? ONE_DIGIT

  end

  Password.new( pw )

end