init

part1/alice.py

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+import hmac
+import hashlib
+
+import secrets
+
+# Generate and write shared key
+
+shared_secret: bytes = secrets.token_bytes(16)
+
+with open('k', 'wb') as file:
+    file.write(shared_secret)
+
+# Take in message and compute hmac
+m = input("Message: ").encode()
+
+hmac_object: hmac.HMAC = hmac.new(shared_secret, m, hashlib.sha256)
+m_hash = hmac_object.digest()
+
+print(f'HMAC: {m_hash}')
+
+# Write hmac digest and message
+
+with open('mactext', 'wb') as file:
+    file.write(m + m_hash)
+
+
+
+

part1/bob.py

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+import hmac
+import hashlib
+
+
+# Import shared secret
+with open('k', 'rb') as file:
+    shared_key = file.read()
+
+# Compute hmac
+with open('mactext', 'rb') as file:
+    data = file.read()
+
+m = data[:18]
+m_hash = data[18:]
+
+hmac_oject: hmac.HMAC = hmac.new(shared_key, m, hashlib.sha256)
+derived_hmac = hmac_oject.digest()
+print(f'Derived HMAC: {hmac_oject.digest()}')
+
+if derived_hmac == m_hash:
+    print("HMAC matches message")
+
+else:
+    print("HMAC does not match message")
+
+
+
+
+