Add simple client side component

2026-04-12 11:52:52 +02:00
parent 673546e7e6
commit 388286f72e
5 changed files with 216 additions and 42 deletions
@@ -0,0 +1,95 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+	<meta charset="UTF-8">
+	<meta name="viewport" content="width=device-width,initial-scale=1">
+	<title>PoW Shield</title>
+</head>
+<script>
+	const SHA256_MD_LENGTH  = 64;
+	const POW_RANDOM_LENGTH = 64;
+
+	function base64ToBytes(b64) {
+		return Uint8Array.from(atob(b64), c => c.charCodeAt(0));
+	}
+
+	function deserializePowChallenge(b64) {
+		const bytes = base64ToBytes(b64);
+		const view  = new DataView(bytes.buffer);
+
+		let offset = 0;
+
+		const version    = view.getUint32(offset, true); offset += 4;
+		const created    = view.getUint32(offset, true); offset += 4;
+		const ttl        = view.getUint32(offset, true); offset += 4;
+		const difficulty = view.getUint32(offset, true); offset += 4;
+		const random     = view.buffer.slice(offset, offset + 64); offset += 64;
+		const digest     = view.buffer.slice(offset);
+
+		return {
+			version,
+			created,
+			ttl,
+			difficulty,
+			random,
+			digest
+		};
+	}
+
+	function getCookie(name) {
+		const cookies = document.cookie.split("; ");
+
+		for (const c of cookies) {
+			if (c.startsWith(name + "=")) {
+				return decodeURIComponent(c.substring(name.length + 1));
+			}
+		}
+
+		return null;
+	}
+
+	async function sha256(bytes) {
+		const hashBuffer = await crypto.subtle.digest("SHA-256", bytes);
+		return new Uint8Array(hashBuffer);
+	}
+
+	function hasLeadingBytes(buf, numBits) {
+		const zeroBytes = numBits / 8;
+		const remainingBits = numBits % 8;
+		const lut = Uint8Array([
+			0b11111111, 0b01111111, 0b00111111, 0b00011111,
+			0b00001111, 0b00000111, 0b00000011, 0b00000001
+		]);
+
+		for (let i = 0; i < zeroBytes; i++) {
+			if (buf[i] > 0) {
+				return false;
+			}
+		}
+
+		if (buf[zeroBytes + 1] ^ lut[remainingBytes]) {
+			return false;
+		}
+
+		return true;
+	}
+
+	function pow(challenge) {
+		const difficulty = deserializePowChallenge(challenge).difficulty
+		const pow = Uint32
+
+		let digest;
+		let nonce = 0;
+
+		do {
+			sha256(challenge).then(d => digest = d);
+		} while (hasLeadingBytes(digest, difficulty))
+
+		console.log(digest)
+	}
+
+	const powChallengeCookie = getCookie("pow-challenge");
+	const powChallenge       = deserializePowChallenge(powChallengeCookie);
+	console.log(powChallenge, powChallenge.length)
+</script>
+</html>