[{"data":1,"prerenderedAt":4},["ShallowReactive",2],{"wpKB0vOJQV":3},"# octra-hfhe-lean\n\nA [Lean 4](https://lean-lang.org) + [Mathlib](https://github.com/leanprover-community/mathlib4) formalization of the **Octra HFHE** scheme, which is an **exact** homomorphic encryption scheme over a finite field 𝔽ₚ (`p = 2^127-1`, the Mersenne prime). Unlike LWE/BGV‑style FHE, **there is no decryption noise**: decryption is an *identity* over 𝔽ₚ, and the scheme's \"noise\" tuples cancel exactly. Consequently there is **no noise budget** that correctness depends on: the only quantity that grows under evaluation is ciphertext **size** (edge count).\n\n**=>** Codebase [OVERVIEW](OVERVIEW.md)\n\n> **Note**: this repository is heavily work in progress, and an **independent** study formalization. Not official associated with Octra. Correctness is the focus; the hardness assumptions are taken as given.\n\n> **Note**: this work is based on the public [octra-labs/pvac_hfhe_cpp](https://github.com/octra-labs/pvac_hfhe_cpp) repository at commit `08f345f` (Jun 13 2026).\n\n## Build\n\n```bash\nlake exe cache get    # fetch Mathlib's prebuilt oleans\nlake build\n```\n\nThe Lean toolchain is pinned in `lean-toolchain`.\n",1783784686830]