EECS 388: P1 - Crypto

Languages & Tools Used: Python

Part 1

• Implemented a length extension attack in Python, exploiting SHA-256’s Merkle-Damgård construction to modify API requests without knowledge of the secret key.
• Developed a script to automate URL forgery, crafting valid API requests that bypass authentication by appending arbitrary commands.
• Demonstrated cryptographic vulnerabilities by generating MD5 hash collisions using the fastcoll tool, proving the insecurity of outdated hashing algorithms.
• Created two Python programs with identical MD5 hashes but different outputs, showcasing the risks of collision attacks in real-world applications.
• Analyzed the security implications of length extension and hash collisions, reinforcing the importance of using HMACs and modern cryptographic functions like SHA-256.

Part 2

• Developed a Python exploit to decrypt AES-CBC encrypted messages by leveraging a padding oracle vulnerability in a web-based encryption system.
• Optimized ciphertext manipulation and batched requests to efficiently recover plaintext without the encryption key.
• Exploited weak PKCS #1 v1.5 RSA padding validation to forge mathematically valid digital signatures.
• Computed modular cube roots to generate fraudulent yet accepted signatures for unauthorized transactions.
• Demonstrated the real-world risks of improper RSA implementation by bypassing signature verification.