diff --git a/unit05_key_exchange/src/d_01.py b/unit05_key_exchange/src/d_01.py
index 0a51f30..4ae129f 100644
--- a/unit05_key_exchange/src/d_01.py
+++ b/unit05_key_exchange/src/d_01.py
@@ -1,18 +1,42 @@
-from os import urandom
-from eccsnacks.curve25519 import scalarmult, scalarmult_base
+from cryptography.hazmat.primitives import hashes
+from cryptography.hazmat.primitives.asymmetric import ec
+from cryptography.hazmat.primitives.kdf.hkdf import HKDF
+from cryptography.hazmat.primitives import serialization
+from cryptography.hazmat.backends import default_backend
+
 import binascii
+import sys
 
-a = urandom(32)
-a_pub = scalarmult_base(a)
 
-b = urandom(32)
-b_pub = scalarmult_base(b)
+size=32 # 256 bit key
 
-k_ab = scalarmult(a, b_pub)
-k_ba = scalarmult(b, a_pub)
+Bob_private_key = ec.generate_private_key(ec.SECP256K1(),default_backend())
+Alice_private_key = ec.generate_private_key(ec.SECP256K1(),default_backend())
 
-print "Bob public: ",binascii.hexlify(b_pub)
-print "Alice public: ",binascii.hexlify(a_pub)
-print "Bob shared: ",binascii.hexlify(k_ba)
-print "Alice shared: ",binascii.hexlify(k_ab)
 
+Bob_shared_key = Bob_private_key.exchange(ec.ECDH(), Alice_private_key.public_key())
+
+Bob_derived_key = HKDF(algorithm=hashes.SHA256(),length=size,salt=None,info=b'',backend=default_backend()).derive(Bob_shared_key)
+
+Alice_shared_key = Alice_private_key.exchange(ec.ECDH(), Bob_private_key.public_key())
+
+Alice_derived_key = HKDF(algorithm=hashes.SHA256(),length=size,salt=None,info=b'',backend=default_backend()).derive(Alice_shared_key)
+
+print ("Name of curve: ",Bob_private_key.public_key().curve.name)
+print (f"Generated key size: {size} bytes ({size*8} bits)")
+
+vals = Bob_private_key.private_numbers()
+print (f"\nBob private key value: {vals.private_value}")
+vals=Bob_private_key.public_key()
+enc_point=binascii.b2a_hex(vals.public_bytes(encoding=serialization.Encoding.PEM,format=serialization.PublicFormat.SubjectPublicKeyInfo)).decode()
+print("Bob's public key: ",enc_point)
+
+vals = Alice_private_key.private_numbers()
+print (f"\nAlice private key value: {vals.private_value}")
+vals=Alice_private_key.public_key()
+enc_point=binascii.b2a_hex(vals.public_bytes(encoding=serialization.Encoding.PEM,format=serialization.PublicFormat.SubjectPublicKeyInfo)).decode()
+print("Alice's public key: ",enc_point)
+
+
+print ("\nBob's derived key: ",binascii.b2a_hex(Bob_derived_key).decode())
+print("Alice's derived key: ",binascii.b2a_hex(Alice_derived_key).decode())