HMAC 계산을 Web Worker에서 처리하도록 변경

src/workers/hmac.ts

@@ -0,0 +1,25 @@
+import { hmac } from "@noble/hashes/hmac.js";
+import { sha256 } from "@noble/hashes/sha2.js";
+
+export interface ComputeMessage {
+  stream: ReadableStream;
+  key: Uint8Array;
+}
+
+export interface ResultMessage {
+  result: Uint8Array;
+}
+
+self.onmessage = async (event: MessageEvent<ComputeMessage>) => {
+  const h = hmac.create(sha256, event.data.key);
+  const reader = event.data.stream.getReader();
+
+  while (true) {
+    const { done, value } = await reader.read();
+    if (done) break;
+    h.update(value);
+  }
+
+  const result = h.digest();
+  self.postMessage({ result } satisfies ResultMessage, { transfer: [result.buffer] });
+};