Principles of Modern Cryptography

Core Principles

The goal is to provide a rigorous proof that a given construction is secure.

The formal definitions should be precise, and be a mathematical model.

Assumptions should be clearly stated and unambiguous.

Secure Encryption Scheme Guaranty

Regardless of any information an attacker already has, a ciphertext should not leak additional information about the underlying plaintext.

Thread Models for Encryption

• Ciphertext-only Attack: Adversary just observes one of more ciphertexts.
• Known-plaintext Attack: Adversary is able to learn one or more plaintext/ciphertext pairs generated using some keys.
• Chosen-plaintext Attack: Adversary can obtain plaintext/ciphertext pairs for plaintext of its choice.
• Chosen-ciphertext Attack: Adversary is additionally able to obtain some information about the decryption of ciphertexts of its choice.