Add Great Wall — Tacit-knowledge seed derivation by fractal recall #2161

Yuri-SVB commented at 6:21 AM on May 17, 2026: none

Summary

This PR submits a new Draft BIP: Great Wall, a procedure for deriving a BIP-0032 master seed from a secret that exists only in the user's memory.

Instead of recording a BIP-0039 mnemonic, the user memorizes a sequence of locations on deterministically rendered Burning Ship fractals. The recalled locations are decoded by a binary bisection algorithm into raw entropy, which is then re-encoded as a BIP-0039 mnemonic and stretched into a seed exactly as in BIP-0039 — so all derived keys and addresses are identical to those a BIP-0039 wallet would produce from the same entropy.

The scheme is built around Tacit Knowledge-Based Authentication (TKBA): the secret is held as non-verbalizable procedural memory, and its deployment is gated by a tunable memory-hard KDF, providing coercion-resistance without any physical backup artifact. It is forward- and backward-compatible with BIP-0039 and composes with Formosa (BIP-0450).

Process notes

Submitted as an unnumbered bip.mediawiki with BIP: ? and Assigned: ? in the preamble.
No number self-assigned and no README table entry added — left for a BIP Editor to assign and publish, following the same path Formosa (BIP-0450) took.
Layer: Applications · Type: Specification · Status: Draft · License: BSD-2-Clause · Requires: 32, 39

Specification: deterministic I4F60 fixed-point arithmetic; the binary bisection algorithm and the regular binary area tree it induces (cuts alternate along the largest dimension; weighted-median placement + contraction yielding a discarded area / checksum-like effect); the app-canonical fractal (fixed baseline perturbation p excluding the degenerate tail of the mathematics-canonical Burning Ship); the KDF-perturbed stage-2 fractal; sizing; recall-to-seed pipeline; computational gating / RSW time-lock; optional inheritance protocol.
Rationale, Backwards Compatibility, Security Considerations, and Reference Implementation sections.

Reference implementation and documentation: https://github.com/Yuri-SVB/Great-Wallet

Checklist

BIP Editor assigns a number and renames bip.mediawiki accordingly
README.mediawiki table entry added on publication
Discussion: link updated to the bitcoindev mailing-list thread (if/when available)

BIP: Great Wall—Tacit-knowledge seed derivation by fractal recall

Add Great Wall as a Draft Applications BIP describing memory-only
BIP-0032 seed derivation via two-stage fractal recall (TKBA), with
KDF/time-lock gating and optional inheritance. Register in README.

- Bisection is strictly binary: each step yields exactly two valid
  halves plus one discarded area, inducing a regular binary area tree.
- Distinguish mathematics-canonical from app-canonical fractal; the
  app-canonical fractal always applies a baseline perturbation p to
  exclude a thin tail prone to bad leaf areas.
- Add weighted-median/contraction heuristics and checksum-like effect.
- Add a Sizing section (32 bits per point) and supporting rationale
  and security notes. Aligned with great-wall-core great-wallet docs.

0ae3084f5d

in bip.mediawiki:10 in 0ae3084f5d

   5 | +  Authors: Yuri S Villas Boas <yuri@t3infosecurity.com>
   6 | +  Status: Draft
   7 | +  Type: Specification
   8 | +  Assigned: ?
   9 | +  License: BSD-2-Clause
  10 | +  Discussion: https://github.com/Yuri-SVB/Great-Wallet

danielabrozzoni commented at 11:28 AM on May 18, 2026:

This should link to the discussion thread on the ML, not to your own repository (which, as far as I can see, doesn't even have issues/PRs where someone discussed the idea...)

danielabrozzoni commented at 11:29 AM on May 18, 2026: member

Hey! BIP3 explicitly states that new BIPs should be discussed on the mailing list first:

https://github.com/bitcoin/bips/blob/6deafd07ff5d38c7d69b27530ba55a4ee038cde7/bip-0003.md?plain=1#L485-L487

I can't find any thread on the mailing list, so I suggest you post this there before opening a BIP PR :)

jonatack closed this on May 18, 2026

jonatack commented at 1:57 PM on May 18, 2026: member

Thank you for your proposal, but it appears to have been opened here prematurely? See the README and BIP 3 for the process (thanks!)

Add Great Wall — Tacit-knowledge seed derivation by fractal recall #2161

Summary

Process notes

Contents

Checklist