New cipher vigenere

Author: aladdinpersson

Algorithms/cryptology/ceasar_shifting_cipher/ceasar_shift_cipher.py

@@ -50,11 +50,4 @@ def main():
     #print('Encrypted message: ' + cipher)
     #print('Decrypted message: ' + decrypted)
 
-
-main()
-
-
-
-
-
-
+main()

Algorithms/cryptology/hill_cipher/test.py

@@ -0,0 +1,56 @@
+'''
+Vigenère cipher is one of the simplest that employs a form of polyalphabetic substitution (each letter is assigned
+more than one substitute).
+
+It was first described in 1553 but took an entire three centuries to break it in 1863.
+
+Weakness: If someone finds key length then this can be broken.
+
+Programmed by Aladdin Persson <aladdin.persson at hotmail dot com>
+*  2019-11-07 Initial programming
+
+'''
+
+
+alphabet = 'abcdefghijklmnopqrstuvwxyz '
+letter_to_index = dict(zip(alphabet, range(len(alphabet))))
+index_to_letter = dict(zip(range(len(alphabet)), alphabet))
+
+
+def encrypt(message, key):
+    encrypted = ''
+    split_message = [message[i:i + len(key)] for i in range(0, len(message), len(key))]
+
+    for each_split in split_message:
+        i = 0
+        for letter in each_split:
+            number = (letter_to_index[letter] + letter_to_index[key[i]]) % len(alphabet)
+            encrypted += index_to_letter[number]
+            i += 1
+
+    return encrypted
+
+def decrypt(cipher, key):
+    decrypted = ''
+    split_encrypted = [cipher[i:i + len(key)] for i in range(0, len(cipher), len(key))]
+
+    for each_split in split_encrypted:
+        i = 0
+        for letter in each_split:
+            number = (letter_to_index[letter] - letter_to_index[key[i]]) % len(alphabet)
+            decrypted += index_to_letter[number]
+            i += 1
+
+    return decrypted
+
+def main():
+    message = 'we attack tomorrow at noon'
+    key = 'secret'
+    encrypted_message = encrypt(message, key)
+    decrypted_message = decrypt(encrypted_message, key)
+
+    # print('Original message: ' + message)
+    # print('Encrypted message: ' + encrypted_message)
+    # print('Decrypted message: ' + decrypted_message)
+
+main()