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diff --git a/news/phase4-wasm-browser-verification/index.html b/news/phase4-wasm-browser-verification/index.html new file mode 100644 index 0000000..571e094 --- /dev/null +++ b/news/phase4-wasm-browser-verification/index.html @@ -0,0 +1,192 @@ +<!DOCTYPE html> +<html lang="en"> +<head> + <meta charset="utf-8"> + <meta name="viewport" content="width=device-width, initial-scale=1"> + <title>Phase 4: Verify Without Installing Anything — Tesseras</title> + <meta name="description" content="Tesseras now compiles to WebAssembly — anyone can verify a tessera's integrity and authenticity directly in the browser, with no software to install."> + <!-- Open Graph --> + <meta property="og:type" content="article"> + <meta property="og:title" content="Phase 4: Verify Without Installing Anything"> + <meta property="og:description" content="Tesseras now compiles to WebAssembly — anyone can verify a tessera's integrity and authenticity directly in the browser, with no software to install."> + <meta property="og:image" content="https://tesseras.net/images/social.jpg"> + <meta property="og:image:width" content="1200"> + <meta property="og:image:height" content="630"> + <meta property="og:site_name" content="Tesseras"> + <!-- Twitter Card --> + <meta name="twitter:card" content="summary_large_image"> + <meta name="twitter:title" content="Phase 4: Verify Without Installing Anything"> + <meta name="twitter:description" content="Tesseras now compiles to WebAssembly — anyone can verify a tessera's integrity and authenticity directly in the browser, with no software to install."> + <meta name="twitter:image" content="https://tesseras.net/images/social.jpg"> + <link rel="stylesheet" href="https://tesseras.net/style.css?h=21f0f32121928ee5c690"> + + + <link rel="alternate" type="application/atom+xml" title="Tesseras" href="https://tesseras.net/atom.xml"> + + + <link rel="icon" type="image/png" sizes="32x32" href="https://tesseras.net/images/favicon.png?h=be4e123a23393b1a027d"> + +</head> +<body> + <header> + <h1> + <a href="https://tesseras.net/"> + <img src="https://tesseras.net/images/logo-64.png?h=c1b8d0c4c5f93b49d40b" alt="Tesseras" width="40" height="40" class="logo"> + Tesseras + </a> + </h1> + <nav> + + <a href="https://tesseras.net/about/">About</a> + <a href="https://tesseras.net/news/">News</a> + <a href="https://tesseras.net/releases/">Releases</a> + <a href="https://tesseras.net/faq/">FAQ</a> + <a href="https://tesseras.net/subscriptions/">Subscriptions</a> + <a href="https://tesseras.net/contact/">Contact</a> + + </nav> + <nav class="lang-switch"> + + <strong>English</strong> | <a href="/pt-br/news/phase4-wasm-browser-verification/">Português</a> + + </nav> + </header> + + <main> + +<article> + <h2>Phase 4: Verify Without Installing Anything</h2> + <p class="news-date">2026-02-15</p> + <p>Trust shouldn't require installing software. If someone sends you a tessera — a +bundle of preserved memories — you should be able to verify it's genuine and +unmodified without downloading an app, creating an account, or trusting a +server. That's what <code>tesseras-wasm</code> delivers: drag a tessera archive into a web +page, and cryptographic verification happens entirely in your browser.</p> +<h2 id="what-was-built">What was built</h2> +<p><strong>tesseras-wasm</strong> — A Rust crate that compiles to WebAssembly via wasm-pack, +exposing four stateless functions to JavaScript. The crate depends on +<code>tesseras-core</code> for manifest parsing and calls cryptographic primitives directly +(blake3, ed25519-dalek) rather than depending on <code>tesseras-crypto</code>, which pulls +in C-based post-quantum libraries that don't compile to +<code>wasm32-unknown-unknown</code>.</p> +<p><code>parse_manifest</code> takes raw MANIFEST bytes (UTF-8 plain text, not MessagePack), +delegates to <code>tesseras_core::manifest::Manifest::parse()</code>, and returns a JSON +string with the creator's Ed25519 public key, signature file paths, and a list +of files with their expected BLAKE3 hashes, sizes, and MIME types. Internal +structs (<code>ManifestJson</code>, <code>CreatorPubkey</code>, <code>SignatureFiles</code>, <code>FileEntry</code>) are +serialized with serde_json. The ML-DSA public key and signature file fields are +present in the JSON contract but set to <code>null</code> — ready for when post-quantum +signing is implemented on the native side.</p> +<p><code>hash_blake3</code> computes a BLAKE3 hash of arbitrary bytes and returns a +64-character hex string. It's called once per file in the tessera to verify +integrity against the MANIFEST.</p> +<p><code>verify_ed25519</code> takes a message, a 64-byte signature, and a 32-byte public key, +constructs an <code>ed25519_dalek::VerifyingKey</code>, and returns whether the signature +is valid. Length validation returns descriptive errors ("Ed25519 public key must +be 32 bytes") rather than panicking.</p> +<p><code>verify_ml_dsa</code> is a stub that returns an error explaining ML-DSA verification +is not yet available. This is deliberate: the <code>ml-dsa</code> crate on crates.io is +v0.1.0-rc.7 (pre-release), and <code>tesseras-crypto</code> uses <code>pqcrypto-dilithium</code> +(C-based CRYSTALS-Dilithium) which is byte-incompatible with FIPS 204 ML-DSA. +Both sides need to use the same pure Rust implementation before +cross-verification works. Ed25519 verification is sufficient — every tessera is +Ed25519-signed.</p> +<p>All four functions use a two-layer pattern for testability: inner functions +return <code>Result<T, String></code> and are tested natively, while thin <code>#[wasm_bindgen]</code> +wrappers convert errors to <code>JsError</code>. This avoids <code>JsError::new()</code> panicking on +non-WASM targets during testing.</p> +<p>The compiled WASM binary is 109 KB raw and 44 KB gzipped — well under the 200 KB +budget. wasm-opt applies <code>-Oz</code> optimization after wasm-pack builds with +<code>opt-level = "z"</code>, LTO, and single codegen unit.</p> +<p><strong>@tesseras/verify</strong> — A TypeScript npm package (<code>crates/tesseras-wasm/js/</code>) +that orchestrates browser-side verification. The public API is a single +function:</p> +<pre><code data-lang="typescript">async function verifyTessera( + archive: Uint8Array, + onProgress?: (current: number, total: number, file: string) => void +): Promise<VerificationResult> +</code></pre> +<p>The <code>VerificationResult</code> type provides everything a UI needs: overall validity, +tessera hash, creator public keys, signature status (valid/invalid/missing for +both Ed25519 and ML-DSA), per-file integrity results with expected and actual +hashes, a list of unexpected files not in the MANIFEST, and an errors array.</p> +<p>Archive unpacking (<code>unpack.ts</code>) handles three formats: gzip-compressed tar +(detected by <code>\x1f\x8b</code> magic bytes, decompressed with fflate then parsed as +tar), ZIP (<code>PK\x03\x04</code> magic, unpacked with fflate's <code>unzipSync</code>), and raw tar +(<code>ustar</code> at offset 257). A <code>normalizePath</code> function strips the leading +<code>tessera-<hash>/</code> prefix so internal paths match MANIFEST entries.</p> +<p>Verification runs in a Web Worker (<code>worker.ts</code>) to keep the UI thread +responsive. The worker initializes the WASM module, unpacks the archive, parses +the MANIFEST, verifies the Ed25519 signature against the creator's public key, +then hashes each file with BLAKE3 and compares against expected values. Progress +messages stream back to the main thread after each file. If any signature is +invalid, verification stops early without hashing files — failing fast on the +most critical check.</p> +<p>The archive is transferred to the worker with zero-copy +(<code>worker.postMessage({ type: "verify", archive }, [archive.buffer])</code>) to avoid +duplicating potentially large tessera files in memory.</p> +<p><strong>Build pipeline</strong> — Three new justfile targets: <code>wasm-build</code> runs wasm-pack +with <code>--target web --release</code> and optimizes with wasm-opt; <code>wasm-size</code> reports +raw and gzipped binary size; <code>test-wasm</code> runs the native test suite.</p> +<p><strong>Tests</strong> — 9 native unit tests cover BLAKE3 hashing (empty input, known value), +Ed25519 verification (valid signature, invalid signature, wrong key, bad key +length), and MANIFEST parsing (valid manifest, invalid UTF-8, garbage input). 3 +WASM integration tests run in headless Chrome via +<code>wasm-pack test --headless --chrome</code>, verifying that <code>hash_blake3</code>, +<code>verify_ed25519</code>, and <code>parse_manifest</code> work correctly when compiled to +<code>wasm32-unknown-unknown</code>.</p> +<h2 id="architecture-decisions">Architecture decisions</h2> +<ul> +<li><strong>No tesseras-crypto dependency</strong>: the WASM crate calls blake3 and +ed25519-dalek directly. <code>tesseras-crypto</code> depends on <code>pqcrypto-kyber</code> (C-based +ML-KEM via pqcrypto-traits) which requires a C compiler toolchain and doesn't +target wasm32. By depending only on pure Rust crates, the WASM build has zero +C dependencies and compiles cleanly to WebAssembly.</li> +<li><strong>ML-DSA deferred, not faked</strong>: rather than silently skipping post-quantum +verification, the stub returns an explicit error. This ensures that if a +tessera contains an ML-DSA signature, the verification result will report +<code>ml_dsa: "missing"</code> rather than pretending it was checked. The JS orchestrator +handles this gracefully — a tessera is valid if Ed25519 passes and ML-DSA is +missing (not yet implemented on either side).</li> +<li><strong>Inner function pattern</strong>: <code>JsError</code> cannot be constructed on non-WASM +targets (it panics). Splitting each function into +<code>foo_inner() -> Result<T, String></code> and <code>foo() -> Result<T, JsError></code> lets the +native test suite exercise all logic without touching JavaScript types. The +WASM integration tests in headless Chrome test the full <code>#[wasm_bindgen]</code> +surface.</li> +<li><strong>Web Worker isolation</strong>: cryptographic operations (especially BLAKE3 over +large media files) can take hundreds of milliseconds. Running in a Worker +prevents UI jank. The streaming progress protocol +(<code>{ type: "progress", current, total, file }</code>) lets the UI show a progress bar +during verification of tesseras with many files.</li> +<li><strong>Zero-copy transfer</strong>: <code>archive.buffer</code> is transferred to the Worker, not +copied. For a 50 MB tessera archive, this avoids doubling memory usage during +verification.</li> +<li><strong>Plain text MANIFEST, not MessagePack</strong>: the WASM crate parses the same +plain-text MANIFEST format as the CLI. This is by design — the MANIFEST is the +tessera's Rosetta Stone, readable by anyone with a text editor. The +<code>rmp-serde</code> dependency in the Cargo.toml is not used and will be removed.</li> +</ul> +<h2 id="what-comes-next">What comes next</h2> +<ul> +<li><strong>Phase 4: Resilience and Scale</strong> — OS packaging (Alpine, Arch, Debian, +FreeBSD, OpenBSD), CI on SourceHut and GitHub Actions, security audits, +browser-based tessera explorer at tesseras.net using @tesseras/verify</li> +<li><strong>Phase 5: Exploration and Culture</strong> — Public tessera browser by +era/location/theme/language, institutional curation, genealogy integration, +physical media export (M-DISC, microfilm, acid-free paper with QR)</li> +</ul> +<p>Verification no longer requires trust in software. A tessera archive dropped +into a browser is verified with the same cryptographic rigor as the CLI — same +BLAKE3 hashes, same Ed25519 signatures, same MANIFEST parser. The difference is +that now anyone can do it.</p> + +</article> + + </main> + + <footer> + <p>© 2026 Tesseras Project. <a href="/atom.xml">News Feed</a> · <a href="https://git.sr.ht/~ijanc/tesseras">Source</a></p> + </footer> +</body> +</html> diff --git a/news/phase4-wasm-browser-verification/index.html.gz b/news/phase4-wasm-browser-verification/index.html.gz Binary files differnew file mode 100644 index 0000000..41c46ac --- /dev/null +++ b/news/phase4-wasm-browser-verification/index.html.gz |