1 files changed, 93 insertions, 0 deletions
diff --git a/web/js/proof-of-work.mjs b/web/js/proof-of-work.mjs
new file mode 100644
index 0000000..b4f9c53
--- /dev/null
+++ b/web/js/proof-of-work.mjs
@@ -0,0 +1,93 @@
+export default function process(data, difficulty = 5, threads = (navigator.hardwareConcurrency || 1)) {
+  console.debug("fast algo");
+  return new Promise((resolve, reject) => {
+    let webWorkerURL = URL.createObjectURL(new Blob([
+      '(', processTask(), ')()'
+    ], { type: 'application/javascript' }));
+
+    const workers = [];
+
+    for (let i = 0; i < threads; i++) {
+      let worker = new Worker(webWorkerURL);
+
+      worker.onmessage = (event) => {
+        workers.forEach(worker => worker.terminate());
+        worker.terminate();
+        resolve(event.data);
+      };
+
+      worker.onerror = (event) => {
+        worker.terminate();
+        reject();
+      };
+
+      worker.postMessage({
+        data,
+        difficulty,
+        nonce: i,
+        threads,
+      });
+
+      workers.push(worker);
+    }
+
+    URL.revokeObjectURL(webWorkerURL);
+  });
+}
+
+function processTask() {
+  return function () {
+    const sha256 = (text) => {
+      const encoded = new TextEncoder().encode(text);
+      return crypto.subtle.digest("SHA-256", encoded.buffer);
+    };
+
+    function uint8ArrayToHexString(arr) {
+      return Array.from(arr)
+        .map((c) => c.toString(16).padStart(2, "0"))
+        .join("");
+    }
+
+    addEventListener('message', async (event) => {
+      let data = event.data.data;
+      let difficulty = event.data.difficulty;
+      let hash;
+      let nonce = event.data.nonce;
+      let threads = event.data.threads;
+
+      while (true) {
+        const currentHash = await sha256(data + nonce);
+        const thisHash = new Uint8Array(currentHash);
+        let valid = true;
+
+        for (let j = 0; j < difficulty; j++) {
+          const byteIndex = Math.floor(j / 2); // which byte we are looking at
+          const nibbleIndex = j % 2; // which nibble in the byte we are looking at (0 is high, 1 is low)
+
+          let nibble = (thisHash[byteIndex] >> (nibbleIndex === 0 ? 4 : 0)) & 0x0F; // Get the nibble
+
+          if (nibble !== 0) {
+            valid = false;
+            break;
+          }
+        }
+
+        if (valid) {
+          hash = uint8ArrayToHexString(thisHash);
+          console.log(hash);
+          break;
+        }
+
+        nonce += threads;
+      }
+
+      postMessage({
+        hash,
+        data,
+        difficulty,
+        nonce,
+      });
+    });
+  }.toString();
+}
+