Lean for Cryptanalysts: A Practical Introduction to Formal Proofs
jedisct1 · x · 2026-10-30
Hosein Hadipour published a hands-on tutorial on using Lean 4 with Mathlib (v4.35.0) to formally verify short mathematical arguments in symmetric-key cryptanalysis — identities connecting distinguishers, S-box properties — that are normally checked by hand and prone to silent errors.
Key points:
- Starts with the invertibility of a Feistel round, then formalizes an identity linking linear and integral sums
- No Lean background required; familiarity with bits, block ciphers, and finite sums suffices
- Downloadable runnable tutorial; explains definitions, theorem statements, proofs, tactics, and the Infoview panel
Readers can adapt the proofs to claims from their own research.
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