Create verginere_cipher.py

encryptor/encryptors/verginere_cipher.py

@@ -0,0 +1,50 @@
+s = input("The operation to be done:\n")
+plain_text =cipher_text= input("Type your text:\n")
+key = input("Type the key here:\n")
+
+def letter_to_number(c):
+    if c.islower():
+        return ord(c.lower()) - ord('a')
+    else :
+        return ord(c.upper()) - ord('A')
+def number_to_letter(n):
+        return chr(n % 26 + ord('A'))
+
+def repeat_string(key, plain_text):
+    number_of_repeats = plain_text // len(key) + 1
+    a_string_repeated = key * number_of_repeats
+    a_string_repeated_to_target = a_string_repeated[:plain_text]
+    return a_string_repeated_to_target
+repeated_string = repeat_string(key, len(plain_text))
+
+if s == "encrypt":
+    def encrypt_letter(repeated_string, plaintext):
+        if plaintext == " ": return plaintext
+        repeated_string = letter_to_number(repeated_string)
+        plaintext = letter_to_number(plaintext)
+        return number_to_letter((plaintext + repeated_string) % 26)
+
+
+    def encrypt(repeated_string, plaintext):
+        return "".join(encrypt_letter(k, p) for (k, p) in zip(repeated_string, plaintext))
+
+
+    print(encrypt(repeated_string, plain_text))
+
+
+elif s == "decrypt":
+    def decrypt_letter(repeated_string, cipher_text):
+        if cipher_text == " ": return cipher_text
+        repeated_string = letter_to_number(repeated_string)
+        cipher_text = letter_to_number(cipher_text)
+        return number_to_letter((cipher_text - repeated_string + 26) % 26)
+
+
+    def decrypt(repeated_string, cipher_text):
+        return "".join(decrypt_letter(h, i) for (h, i) in zip(repeated_string, cipher_text))
+
+
+    print(decrypt(repeated_string, cipher_text))
+
+
+else : print("Not possible")