Prove OpenSSL PQ crypto in browser WASI and document the migration

1 files changed, 106 insertions, 0 deletions

diff --git a/crates/chat-crypto/browser/wasi.mjs b/crates/chat-crypto/browser/wasi.mjs
new file mode 100644
index 0000000..d27fe4b
--- /dev/null
+++ b/crates/chat-crypto/browser/wasi.mjs
@@ -0,0 +1,106 @@
+// Copyright (C) 2026 Doan Luu Duc Tai <doan@luuduct.ai>
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as
+// published by the Free Software Foundation, either version 3 of the
+// License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+// @license magnet:?xt=urn:btih:0b31508aeb0634b347b8270c7bee4d411b5d4109&dn=agpl-3.0.txt AGPL-3.0
+
+export async function runProbe(bytes) {
+    let memory;
+    let output = '';
+    let errors = '';
+    let randomCalls = 0;
+    let randomBytes = 0;
+    const data = () => new DataView(memory.buffer);
+    const put32 = (address, value) => data().setUint32(address, value, true);
+    const noEntries = (count, size) => { put32(count, 0); put32(size, 0); return 0; };
+    class Exit extends Error {
+        constructor(code) { super(`WASI exit ${code}`); this.code = code; }
+    }
+    const wasi = {
+        args_sizes_get: noEntries,
+        environ_sizes_get: noEntries,
+        args_get: () => 0,
+        environ_get: () => 0,
+        random_get(address, length) {
+            const buffer = new Uint8Array(memory.buffer, address, length);
+            for (let offset = 0; offset < length; offset += 65536) {
+                crypto.getRandomValues(buffer.subarray(offset, Math.min(offset + 65536, length)));
+            }
+            randomCalls += 1;
+            randomBytes += length;
+            return 0;
+        },
+        clock_time_get(clock, precision, address) {
+            if (clock !== 0 && clock !== 1) return 52;
+            const milliseconds = clock === 0 ? Date.now() : performance.now();
+            data().setBigUint64(address, BigInt(Math.floor(milliseconds * 1000000)), true);
+            return 0;
+        },
+        clock_res_get(clock, address) { data().setBigUint64(address, 1000000n, true); return 0; },
+        fd_write(fd, vectors, count, written) {
+            if (fd !== 1 && fd !== 2) return 8;
+            let total = 0;
+            for (let index = 0; index < count; index += 1) {
+                const address = data().getUint32(vectors + index * 8, true);
+                const length = data().getUint32(vectors + index * 8 + 4, true);
+                const text = new TextDecoder().decode(new Uint8Array(memory.buffer, address, length));
+                if (fd === 1) output += text; else errors += text;
+                total += length;
+                if (output.length + errors.length > 65536) throw new Error('Probe output exceeded its limit');
+            }
+            put32(written, total);
+            return 0;
+        },
+        fd_read(fd, vectors, count, read) { if (fd !== 0) return 8; put32(read, 0); return 0; },
+        fd_fdstat_get(fd, address) {
+            if (fd > 2) return 8;
+            new Uint8Array(memory.buffer, address, 24).fill(0);
+            data().setUint8(address, 2);
+            return 0;
+        },
+        fd_fdstat_set_flags: fd => fd <= 2 ? 0 : 8,
+        fd_prestat_get: () => 8,
+        fd_prestat_dir_name: () => 8,
+        fd_close: fd => fd <= 2 ? 0 : 8,
+        fd_seek: () => 70,
+        fd_tell: () => 70,
+        fd_filestat_get: () => 8,
+        path_open: () => 76,
+        sched_yield: () => 0,
+        proc_exit(code) { throw new Exit(code); },
+    };
+    for (const name of [
+        'fd_readdir', 'fd_advise', 'fd_allocate', 'fd_datasync', 'fd_sync',
+        'fd_filestat_set_size', 'fd_filestat_set_times', 'fd_fdstat_set_rights',
+        'path_filestat_get', 'path_filestat_set_times', 'path_readlink', 'path_unlink_file',
+        'path_rename', 'path_create_directory', 'path_remove_directory', 'path_link', 'path_symlink',
+        'sock_accept', 'sock_recv', 'sock_send', 'sock_shutdown', 'poll_oneoff',
+    ]) wasi[name] = () => 76;
+    const module = await WebAssembly.compile(bytes);
+    for (const entry of WebAssembly.Module.imports(module)) {
+        if (entry.module !== 'wasi_snapshot_preview1' || typeof wasi[entry.name] !== 'function') {
+            throw new Error(`Unsupported WASI import: ${entry.module}.${entry.name}`);
+        }
+    }
+    const instance = await WebAssembly.instantiate(module, { wasi_snapshot_preview1: wasi });
+    memory = instance.exports.memory;
+    try { instance.exports._start(); }
+    catch (error) { if (!(error instanceof Exit) || error.code !== 0) throw new Error(`${error.message}: ${errors}`); }
+    if (!output.startsWith('PASS: backend=OpenSSL ') || randomCalls === 0) {
+        throw new Error(`OpenSSL probe did not pass: ${errors || output}`);
+    }
+    return { output, randomCalls, randomBytes };
+}
+
+// @license-end