# File lib/quiz1/t/solutions/Jim Menard/solitaire_cypher.rb, line 141
    def decrypt(str)
        @deck = @keyed_deck.dup
        answer = ""
        str.split(//).each { | c |
            if c == ' '
                answer << ' '
                next
            end

            msg_num = Card.chr_to_value(c)
            key = @deck.next_keystream
            diff = msg_num - key
            diff += 26 if diff < 1
            answer << Card.value_to_chr(diff)
        }
        answer
    end