caesar_encryptor.rb

# Array get cycle
# KEY cyclical enumerator

KEY = "code"
SYMBOLS = ["a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z","1","2","3"]

def encrypt(input_text)
  crypt input_text, false
end

def decrypt(input_text)
  crypt input_text, true
end

def crypt(input_text, decrypt)
  key_idx = -1
  input_text.chars.map do |letter|
    if letter == " "
      letter
    else
      key_idx += 1
      draaing  = decrypt ? -key_index(key_idx) : key_index(key_idx)
      letter_mepper letter, draaing
    end
  end.join
end

def key_index offset
  SYMBOLS.find_index(key_letter(offset))
end

def key_letter offset
  KEY[offset % KEY.length]
end

def letter_mepper(input_symbol, draaing)
  new_index = SYMBOLS.find_index(input_symbol) + draaing
  SYMBOLS[new_index % SYMBOLS.length]
end


input = "jij hebt dit voor helemaal niks ontcijferd"
ciphertext = encrypt(input)
puts "'#{input}' encrypted is '#{ciphertext}'"

decrypted = decrypt(ciphertext)
puts "'#{ciphertext}' decrypted is '#{decrypted}'"

De Caesar en-/decryptor van Brecht uit de Feynmanklas!