Create vernam_cipher.py

ciphers/vernam_cipher.py

@@ -0,0 +1,45 @@
+def vernam_encrypt(plaintext: str, key: str) -> str:
+    ciphertext = ""
+    for i in range(len(plaintext)):
+        ct = ord(key[i % len(key)]) - 65 + ord(plaintext[i]) - 65
+        while ct > 25:
+            ct = ct - 26
+        ciphertext += chr(65 + ct)
+     """
+    >>> vernam_encrypt("HELLO","KEY")
+    'RIJVS'
+    """
+    return ciphertext
+
+def vernam_decrypt(ciphertext: str, key: str) -> str:
+    decrypted_text = ""
+    for i in range(len(ciphertext)):
+        ct = ord(ciphertext[i]) - ord(key[i % len(key)])
+        while ct < 0:
+            ct = 26 + ct
+        decrypted_text += chr(65 + ct)
+    """
+    >>> vernam_decrypt("RIJVS","KEY")
+    'HELLO'
+    """
+    return decrypted_text
+
+
+# Example usage
+plaintext = input("Enter the message: ").upper()
+key = input("Enter the key: ").upper()
+encrypted_text = vernam_encrypt(plaintext, key)
+decrypted_text = vernam_decrypt(encrypted_text, key)
+
+print("\n\n")
+print("Plaintext:", plaintext)
+print("Encrypted:", encrypted_text)
+print("Decrypted:", decrypted_text)
+
+# Tests
+
+#encrypt_txt = vernam_encrypt("HELLO", "KEY")
+#print(encrypt_txt)
+
+#decrypt_txt = vernam_decrypt(encrypt_txt, "KEY")
+#print(decrypt_txt)