Cryptographic Structures - Practical Work #1

Authors: Pedro Carvalho (Github), Miguel Guimarães (Github).

University of Minho - Masters Degree in Software Engineering

February 2025

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Tasks:

Task #1: Use the 'cryptography' package to create a private asynchronous communication between an Emitter agent and a Receiver agent that covers the following aspects:

1. Client-server communication using the python package 'asyncio'.
2. Use the SHAKE-256 hash in XOFHash mode as a AEAD (authenticated) cipher.
3. The cipher keys and nounces are generated by a KDF generator. The different keys for KDF initialization are given as inputs for the emitter and the receiver.

Task #2: Use the 'cryptography' package to:

1. Implement an AEAD with “Tweakable Block Ciphers” as described in the last section of the 'Chapter 1: Basic Cryptographic Primitives'. The primitive block cipher used to generate the “tweakable block cipher” is AES-128.
2. Use this cipher to build a private asynchronous information channel with key agreement made with “X25519 key exchange” and “Ed25519 Signing&Verification” for agent authentication. It must include the confirmation of the agreed key.