From 324b328a4c35ca3af545d5dfe16d381364831f25 Mon Sep 17 00:00:00 2001
From: saizsassin <39055732+saizsassin@users.noreply.github.com>
Date: Thu, 21 Jun 2018 15:02:30 +0530
Subject: [PATCH] Update Aes256.py

---
 Aes256.py | 69 ++++++++++++++++++++++++++++---------------------------
 1 file changed, 35 insertions(+), 34 deletions(-)

diff --git a/Aes256.py b/Aes256.py
index 9ec0117..45dfb8e 100644
--- a/Aes256.py
+++ b/Aes256.py
@@ -2,39 +2,40 @@
 import os
 from Crypto.Cipher import AES
 
-#Generating random key of 32 bytes
-key=os.urandom(32)
-print("Key Generated")
-print(key)
-#Initialization vector in AES should be 16 bytes
-IV = 16*'\x00'
-#Mode of encryption CBC
-mode = AES.MODE_CBC
-#Creation of encryptor and decryptor object using above details 
-encryptor=AES.new(key,mode,IV=IV)
-decryptor=AES.new(key,mode,IV=IV)
+def pad(data):
+    padding = 16 - len(data) % 16
+    return data + padding * chr(padding)
 
-def encrypt(msg):
-    n=len(msg)
-    #Checking for length of msg to be multiple of 16 as it is required in aes encryption
-    if n==0:
-        return
-    elif n%16!=0:
-        msg+=' '*(16-(n%16))        #padding with spaces inorder to make the len of msg to be a multiple of 16 
-    cipher=encryptor.encrypt(msg)
-    print("Encrypted Text")
-    print(cipher)
-    print("Checking for decryption")
-    text=decryptor.decrypt(cipher);
-    #Checking if decrypted text is padded with spaces,so it has been removed by using orignal length of msg
-    length=len(text)
-    if(length>n):
-        plain_text=text[:n]
-    else:
-        plain_text=text
-    print("Decrypted Text")
-    print(plain_text)
+def unpad(data):
+    return data[0:-ord(data[-1])]
 
-msg=input('Enter The Message To Be Encrypted\n')
-#calling encrypt function
-encrypt(msg)
+def keyGen():
+    #Generating random key of 32 bytes
+    key=os.urandom(32)
+    #print("Key Generated")
+    #print(key)
+    return key
+
+
+def encryptMsg(plaintext,key):
+    #Initialization vector in AES should be 16 bytes
+    IV = 16*'\x00'
+    #Creation of encryptor and decryptor object using above details 
+    cipher=AES.new(key,AES.MODE_CBC,IV)
+    return cipher.encrypt(pad(plaintext))
+
+def decryptMsg(ciphertext, key):
+    #Initialization vector in AES should be 16 bytes
+    IV = 16*'\x00'
+    #Creation of encryptor and decryptor object using above details 
+    cipher=AES.new(key,AES.MODE_CBC,IV)
+    return unpad(cipher.decrypt(cipher));
+    
+
+msg=input('Enter The Message To Be Encrypted : ')
+key = keyGen()
+print("Key generated : "+str(key))
+ciphertext = encryptMsg(msg,key)
+print("Encrypted Text : "+str(ciphertext.encode(hex)))
+plaintext = decryptMsg(ciphertext, key)
+print("Decrypted Text : "+str(plaintext))