Schiavinato Sharing (JS/TS)

⚠️ WARNING: EXPERIMENTAL SOFTWARE ⚠️

DO NOT USE IT FOR REAL FUNDS!

Schiavinato Sharing specification and implementations have NOT been audited. Use for testing, learning, and experimentation only. See SECURITY for details.

We invite cryptographers and developers to review the spec and software. See CONTRIBUTING to know more.

JavaScript/TypeScript implementation of Schiavinato Sharing: dual-mode (manual + software) (k)-of-(n) threshold secret sharing for BIP39 mnemonics over GF(2053). Designed for offline/air-gapped workflows, with manual-fallback compatibility.

What is this?

Schiavinato Sharing is a dual-mode (manual + software) (k)-of-(n) threshold secret sharing scheme for BIP39 mnemonics. It operates directly on the 1-indexed BIP39 word indices over the prime field GF(2053), so the recovered secret is a standard BIP39 mnemonic compatible with modern wallets.

In this JS implementation, you can:

• Split a BIP39 mnemonic into (k)-of-(n) shares (Share[])
• Recover the original BIP39 mnemonic from (k) shares (RecoveryResult)
• Validate inputs and share integrity during split/recovery to prevent silent mistakes

Links

• Canonical protocol + specs: schiavinato-sharing
• Whitepaper: PDF | LaTeX
• Test Vectors: TEST_VECTORS
• Canonical security posture: SECURITY
• HTML implementation: schiavinato-sharing-html
• Python implementation: schiavinato-sharing-py
• Validator (dev tool): validator/README.md

Security

This library implements well-established cryptographic principles but has NOT been professionally audited.

Use only for: testing, learning, experimentation.

Canonical security posture: schiavinato-sharing/SECURITY

Verify Before Use (Required)

CRITICAL: Before using with real crypto seeds, verify the package and/or release artifacts haven't been tampered with.

Option A: Verify release artifacts (recommended for highest assurance)

This repository's releases include:

• CHECKSUMS-LIBRARY.txt (+ detached signature CHECKSUMS-LIBRARY.txt.asc)
• A signed release tarball schiavinato-sharing-vX.Y.Z.tar.gz (+ *.asc + *.sha256)

Import the GRIFORTIS public key and verify signatures before use.

curl -fsSL https://raw.githubusercontent.com/GRIFORTIS/schiavinato-sharing-js/main/GRIFORTIS-PGP-PUBLIC-KEY.asc | gpg --import
gpg --fingerprint [email protected]

Expected: 7921 FD56 9450 8DA4 020E 671F 4CFE 6248 C57F 15DF

Then verify release assets (examples):

gpg --verify CHECKSUMS-LIBRARY.txt.asc CHECKSUMS-LIBRARY.txt
gpg --verify schiavinato-sharing-vX.Y.Z.tar.gz.asc schiavinato-sharing-vX.Y.Z.tar.gz

If you've built the library locally, you can also verify the built outputs against the latest release checksums:

npm run build
npm run build:browser
npm run verify:latest

Option B: Verify the NPM tarball identity (supply-chain sanity check)

For NPM installs, verify the published tarball matches the tag/build:

• Compare dist.shasum / dist.integrity from npm view against the values produced by npm pack --json
• Pin exact versions and use lockfiles for repeatable installs

Installation

npm install @grifortis/schiavinato-sharing

Quick Start

Split a mnemonic

import { recoverMnemonic, splitMnemonic } from '@grifortis/schiavinato-sharing';

async function main() {
  const mnemonic =
    'abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon about';

  const shares = await splitMnemonic(mnemonic, 2, 3);
  const result = await recoverMnemonic([shares[0], shares[1]], 12);

  if (!result.success) throw new Error(String(result.errors.generic ?? 'Recovery failed'));
  console.log(result.mnemonic);
}

main();

Recover a mnemonic

Use recoverMnemonic(shares, wordCount) and check result.success (it returns a report object instead of throwing on validation failures).

API Reference (high-level)

Stable entry points:

• splitMnemonic(mnemonic, k, n, options?) (async)
• recoverMnemonic(shares, wordCount, options?) (async)
• validateBip39Mnemonic(mnemonic)

Advanced exports (field arithmetic, Lagrange helpers, checksum helpers, secure wipe utilities) are also available for integration/testing; see the TypeScript types and module exports in src/index.ts.

Conformance Validation

This implementation is validated against canonical test vectors:

• TEST_VECTORS

Functional Validation (Run Tests)

npm ci
npm test
npm run test:coverage
npm run lint
npm run typecheck

See TESTING.md for details.

Validator (Dev Tool Only)

This repo includes a browser-based validator under validator/ for development/testing/auditing workflows. It is not a wallet tool and must not be used with real funds.

See validator/README for features, required validation steps, and usage.

Compatibility

• Spec version: v0.4.0
• Node.js: 18+

Contributing

See CONTRIBUTING.md.

License

MIT License