caesar.rb

# Caesar Cipher
# Write a function to encrypt a message (by shifting char code up or down). Write a function to decrypt a message
#
# Useful methods:
# - http://ruby-doc.org/core-2.2.0/String.html#method-i-ord
# - http://ruby-doc.org/core-2.0.0/String.html#method-i-chr

OFFSET = 3

def encrypt(message)
  encrypted = ""
  message.each_char {|c| encrypted << (c.ord+OFFSET).chr }
  encrypted
end

def decrypt(message)
  decrypted = ""
  message.each_char {|c| decrypted << (c.ord-OFFSET).chr }
  decrypted
end

# http://blog.steveklabnik.com/posts/2011-08-19-matz-is-nice-so-we-are-nice
message = "Matz is Nice So We Are Nice"
puts "Original msg:  #{message}"

messageEncrypted = encrypt(message)
puts "Encrypted msg: #{messageEncrypted}"

messageDecrypted = decrypt(messageEncrypted)
puts "Decrypted msg: #{messageDecrypted}"