Ruby dropped-key generator, for when your broken keyboard loses 1+ keys while typing a password

gistfile1.txt

#!/usr/bin/env ruby
#

BASEWORD = ARGV[0] || raise("No baseword specified")

base_chars = BASEWORD.split('')
rv = []
(1..(base_chars.length - 1)).each do |permutation_len|
  possible = base_chars.permutation(permutation_len).to_a
  filtered = possible.find_all do |chars|
    # A word is legal if it doesn't violate the ordering of the original letters, e.g.
    # BASEWORD: foobar OK: oobar oob ooba NOT: rab roo abf
    if chars.length == 1
      true
    else
      # For every character being tested, we should be able to find it as we scan along
      # the baseword, starting at the position of the character in the set we're testing.
      # E.g. BASE: foobar TEST: fbr - we want to find 'f' at position 0, 'b' at position 1 or later,
      # and 'r' at position 2 or later
      legal = true
      last_pos = 0
      chars.each_with_index do |c, idx|
        #puts "testing: #{c} from #{chars.join('')}"
        pos = base_chars[0..-1].index(c)
        if pos.nil?
          legal = false
          break
        elsif pos < last_pos
          legal = false
          break
        else
          last_pos = pos
        end
      end
      #puts "legal: #{legal} - #{chars.join('')}"
      legal
    end
  end
  rv += filtered.collect{|chars| chars.join('')}
end

rv << BASEWORD
puts rv.join("\n")