1 files changed, 28 insertions, 0 deletions
diff --git a/srv/src/http/static/solvePow.js b/srv/src/http/static/solvePow.js
new file mode 100644
index 0000000..900400c
--- /dev/null
+++ b/srv/src/http/static/solvePow.js
@@ -0,0 +1,28 @@
+const fromHexString = hexString =>
+  new Uint8Array(hexString.match(/.{1,2}/g).map(byte => parseInt(byte, 16)));
+
+const toHexString = bytes =>
+  bytes.reduce((str, byte) => str + byte.toString(16).padStart(2, '0'), '');
+
+onmessage = async (e) => {
+  const seed = fromHexString(e.data.seedHex);
+  const target = e.data.target;
+
+  const fullBuf = new ArrayBuffer(seed.byteLength*2);
+
+  const fullBufSeed = new Uint8Array(fullBuf, 0, seed.byteLength);
+  seed.forEach((v, i) => fullBufSeed[i] = v);
+
+  const randBuf = new Uint8Array(fullBuf, seed.byteLength);
+
+  while (true) {
+    crypto.getRandomValues(randBuf);
+    const digest = await crypto.subtle.digest('SHA-512', fullBuf);
+    const digestView = new DataView(digest);
+    if (digestView.getUint32(0) < target) {
+      postMessage(toHexString(randBuf));
+      return;
+    }
+  }
+
+};