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WASM browser demo

The csmt-verify sublibrary is cross-compiled to WebAssembly via the GHC WASM backend. The resulting csmt-verify.wasm module runs in any WASI-capable host, including a browser using the @bjorn3/browser_wasi_shim polyfill.

Try it

Open the standalone demo

The demo ships:

  • csmt-verify.wasm — the actual binary produced by wasm32-wasi-cabal via nix build .#csmt-verify-wasm
  • index.html + verify.js — a minimal static page that loads the module, pipes a byte-level stdin into it, and reports the exit code
  • fixtures.json — the same proof fixtures used by the TypeScript verifier tests, so the page can exercise inclusion and exclusion proofs out of the box

The Tamper root / Tamper proof buttons flip a byte so you can watch the verifier reject a corrupted proof in real time — no server round-trip, the sandboxed WebAssembly module does the work.

Stdin protocol

The WASM executable reads the entire stdin and returns via exit code:

Bytes Meaning
1 opcode: 0 = inclusion, 1 = exclusion
32 trusted root hash (raw bytes)
remainder CBOR-encoded proof

Exit code 0 means the proof verifies against the supplied root; exit code 1 means it does not (or the input was malformed).

Build it yourself

nix build .#csmt-verify-wasm
nix build .#csmt-verify-wasm-demo
PORT=8000 nix run .#csmt-verify-wasm-demo

The output is a plain tree of static files suitable for copying into any static host.