diff --git a/unit02_symmetric/src/d_01.py b/unit02_symmetric/src/d_01.py
index 25989f2..09ef0d9 100644
--- a/unit02_symmetric/src/d_01.py
+++ b/unit02_symmetric/src/d_01.py
@@ -1,5 +1,35 @@
-import passlib.hash;
-string="hello"
-print ("LM Hash:"+passlib.hash.lmhash.encrypt(string))
-print ("NT Hash:"+passlib.hash.nthash.encrypt(string))
+from Crypto.Cipher import AES
+import hashlib
+import sys
+import binascii
+import Padding
 
+val='hello'
+password='hello'
+
+plaintext=val
+
+def encrypt(plaintext,key, mode):
+	encobj = AES.new(key,mode)
+	return(encobj.encrypt(plaintext))
+
+def decrypt(ciphertext,key, mode):
+	encobj = AES.new(key,mode)
+	return(encobj.decrypt(ciphertext))
+
+key = hashlib.sha256(password.encode()).digest()
+
+
+plaintext = Padding.appendPadding(plaintext,blocksize=Padding.AES_blocksize,mode='CMS')
+
+print("After padding (CMS): ",binascii.hexlify(bytearray(plaintext.encode())))
+
+ciphertext = encrypt(plaintext.encode(),key,AES.MODE_ECB)
+print("Cipher (ECB): ",binascii.hexlify(bytearray(ciphertext)))
+
+plaintext = decrypt(ciphertext,key,AES.MODE_ECB)
+
+plaintext = Padding.removePadding(plaintext.decode(),mode='CMS')
+print("  decrypt: ",plaintext)
+
+plaintext=val