Two-square cipher in ruby (https://en.wikipedia.org/wiki/Two-square_cipher).

two_square.rb

require 'matrix'

class TwoSquare
  attr_accessor :first_square, :second_square

  ALPHABET = 'йцукенгшщзхъэждлорпавыфячсмитьбю.,- '.split('')

  def initialize
    @first_square = build_square
    @second_square = build_square
  end

  def build_square
    alphabet = ALPHABET.shuffle.each_slice(6).to_a
    Matrix[*alphabet]
  end

  def encode_text(string)
    string.chars.each_slice(2).
      map { |(x, y)| encode(x, y) }.
      flatten.join
  end

  alias_method :decode_text, :encode_text

  def encode(first, second)
    first_coors = first_square.index first
    second_coors = second_square.index second
    first_encoded = first_square[first_coors[0], second_coors[1]]
    second_encoded = second_square[second_coors[0], first_coors[1]]
    [first_encoded, second_encoded]
  end

  alias_method :decode, :encode
end

cypher = TwoSquare.new
test_string = 'съешь ка еще этих французских булок, да выпей чаю.'
encoded = cypher.encode_text test_string
decoded = cypher.decode_text encoded

puts test_string
puts encoded
puts decoded