ERC-8213

Wallet Signature & Calldata Digest Display
Cryptographic fingerprints, displayed honestly.

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Table of contents

• Table of contents
• About
• What ERC-8213 standardises
• Site map
• Quick start
• Project structure
• Scripts
• Deployment
  • Vercel
  • IPFS / static host
• Cross-repo digest parity
• Contributing
• License

About

A small, static documentation site for ERC-8213 — an Ethereum standard that asks wallets to display short, reproducible cryptographic fingerprints (digests) for the things a user is about to sign, so signing decisions can be independently verified.

The site is intended for four audiences:

1. Curious users — what is this and why does it matter?
2. Wallet developers — what do I compute and where do I display it?
3. Signers — how do I check that a digest my wallet shows me is correct?
4. The mathematically curious — show me every byte from typed data to digest.

What ERC-8213 standardises

Digest	Formula	Used for
EIP-712 Digest	keccak256(0x1901 ‖ domainSeparator ‖ hashStruct(message))	The single value an ECDSA signer signs for typed data.
Domain Hash	hashStruct(eip712Domain)	Fingerprint of the dapp's claimed identity.
Message Hash	hashStruct(message)	Fingerprint of the typed message.
Calldata Digest	keccak256(uint256(len(calldata)) ‖ calldata)	Length-prefixed fingerprint of raw transaction calldata. ChainId is intentionally not included.

Site map

Route	Purpose
/	Overview · the four digests at a glance · why they matter.
/wallets	Live support matrix. Logos pulled from walletbeat. Updates land via PR.
/implement	Builder guide: decision tree, display rules, reference snippets in TypeScript, Rust, and Swift, common pitfalls.
/verify	Client-side verifier. Paste typed-data JSON or 0x… calldata and watch the four digests recompute live.
/compute	Pedagogical walkthrough: every type string, typeHash, struct hash, EIP-191 preimage, and final digest, traced byte by byte.

Quick start

# Install deps (pnpm preferred — repo ships pnpm-lock.yaml)
pnpm install

# Run the dev server
pnpm dev

Then open http://localhost:3000.

Requires Node.js 20 LTS or 22 LTS, and pnpm 9+.
Other package managers work — replace pnpm with npm or yarn in any command below.

Project structure

app/
├── components/        Reusable UI primitives (Frame, DigestPanel, CopyHex, …)
├── lib/
│   ├── digests.ts     viem-based EIP-712 + calldata digest computation
│   └── example.ts     Canonical Permit2 + Uniswap V3 fixtures
├── wallets/
│   ├── data.ts        Wallet support matrix (PR-friendly JSON-shape)
│   └── page.tsx
├── verify/            Client-side verifier (uses lib/digests.ts in the browser)
├── compute/           Pedagogical walkthrough (build-time digests)
├── implement/         Builder guide
├── globals.css        Theme tokens, frame/grain/typography styles
├── layout.tsx         Root layout, fonts, nav, footer
├── page.tsx           Overview / homepage
├── icon.svg           Primary favicon (modern browsers)
├── favicon.ico        Legacy favicon
└── apple-icon.png     iOS home-screen icon

public/
└── wallets/           Brand SVGs sourced from walletbeat

Scripts

Command	What it does
pnpm dev	Start Next.js dev server with Turbopack.
pnpm build	Production build → static export in out/.
pnpm start	Serve the production build (mostly a no-op for output: "export").
pnpm lint	Run eslint. The repo has a zero-warnings policy.

Deployment

Vercel

The site is a vanilla Next.js project with output: "export". Connect the repo on Vercel and ship — no environment variables required.

IPFS / static host

pnpm build emits a fully static site to out/ with relative routes (trailingSlash: true, images: { unoptimized: true }). It runs from any static host or directly from IPFS:

pnpm build
# ipfs add -r out/
# or upload `out/` to S3 / Cloudflare Pages / GitHub Pages / etc.

Cross-repo digest parity

Digest math in this repo uses viem. The companion repo cyfrin/chain-tools implements the same digests with ethers, plus a Python reference implementation. A vitest suite over there imports both libraries and asserts byte-for-byte equality on shared fixtures (src/lib/erc8213-parity.test.ts).

If you change the digest implementation here, run that parity test before publishing — drift between the two libraries would mean a wallet verifying against one would see a false mismatch on the other.

Contributing

The most useful contribution is updating the wallet support matrix. Edit app/wallets/data.ts, open a PR, and:

• Reference the wallet's release notes or commit that adds digest display.
• Drop the brand SVG in public/wallets/ (sourced from walletbeat when possible, so logos stay consistent across the ecosystem).
• Bump lastUpdated in the same file.

Code-level contributions: open an issue first if it's a non-trivial change. The site is intentionally small and tries to stay that way.

License

Released under the MIT License © 2026 Cyfrin Inc.