Implemented Vernam cipher

README.md

@@ -54,6 +54,10 @@ decryptrot13 = Rot13::decrypt("uryy? }?.yqb") #"hello world!"
 
 #Binary encrypt
 Binary::encrypt("hello world") # "1101000 1100101 1101100 1101100 1101111 100000 1110111 1101111 1110010 1101100 1100100 100001"
+
+#Vernam encrypt
+Vernam::encrypt("HELLOWORLD","ZXC795JRTQ")#"61N{BFX84T"
+Vernam.decrypt("61N{BFX84T","ZXC795JRTQ")#"HELLOWORLD"
 ```
 ## Development
 

lib/aaa_crypt.rb

@@ -6,6 +6,7 @@
 require_relative 'cesar/cesar'
 require_relative 'visener/visener'
 require_relative 'aaa_crypt/rot13'
+require_relative 'aaa_crypt/vernam'
 
 
 module AaaCrypt

lib/aaa_crypt/vernam.rb

@@ -0,0 +1,29 @@
+module AaaCrypt
+  module Vernam
+
+    ALPHABET = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789!?:;.,(){}[]"
+    def self.encrypt(word, key)
+      raise Error if word.length > key.length
+
+      encrypted_word = ''
+      index = 0
+      word.upcase.split('').map do |s|
+        encrypted_word += ALPHABET[(ALPHABET.index(s) + ALPHABET.index(key[index].upcase)) % 48]
+        index += 1
+      end
+      encrypted_word
+    end
+
+    def self.decrypt(encrypted_word, key)
+      raise Error if encrypted_word.length > key.length
+
+      decrypted_word = ''
+      index = 0
+      encrypted_word.upcase.split('').map do |s|
+        decrypted_word += ALPHABET[(ALPHABET.index(s) - ALPHABET.index(key[index].upcase)) % 48]
+        index += 1
+      end
+      decrypted_word
+    end
+  end
+end

test/encryption/vernam_test.rb

@@ -0,0 +1,37 @@
+require 'minitest/autorun'
+require_relative "../test_helper"
+
+class VernamTest < Minitest::Test
+  include AaaCrypt
+  include AaaCrypt::Vernam
+
+  def test_vernam_encrypt_a
+    assert_equal("C",Vernam.encrypt("A","C"))
+  end
+
+  def test_vernam_decrypt_a
+    assert_equal("A",Vernam.decrypt("C","C"))
+  end
+
+  def test_vernam_encrypt_hw
+    assert_equal("61N{BFX84T",Vernam.encrypt("HELLOWORLD","ZXC795JRTQ"))
+  end
+
+  def test_vernam_decrypt_hw
+    assert_equal("HELLOWORLD",Vernam.decrypt("61N{BFX84T","ZXC795JRTQ"))
+  end
+
+  def test_vernam_encrypt_hw_mixed_case
+    assert_equal("61N{BFX84T",Vernam.encrypt("HeLlOwORlD","Zxc795jRtQ"))
+  end
+
+  def test_vernam_decrypt_hw_mixed_case
+    assert_equal("HELLOWORLD",Vernam.decrypt("61n{Bfx84T","Zxc795jRtQ"))
+  end
+
+  def test_vernam_word_longer_than_key
+    assert_raises Error do
+      Vernam.encrypt("HELLOWORLD","ZXC795JRT")
+    end
+  end
+end