diff --git a/src/lib/modules/crypto/hmac.worker.ts b/src/lib/modules/crypto/hmac.worker.ts
new file mode 100644
index 0000000..5d32189
--- /dev/null
+++ b/src/lib/modules/crypto/hmac.worker.ts
@@ -0,0 +1,30 @@
+import { hmac } from "@noble/hashes/hmac.js";
+import { sha256 } from "@noble/hashes/sha2.js";
+
+interface ComputeMessage {
+  type: "compute";
+  file: File;
+  hmacSecret: ArrayBuffer;
+}
+
+type WorkerMessage = ComputeMessage;
+
+self.onmessage = async (event: MessageEvent<WorkerMessage>) => {
+  const { type } = event.data;
+
+  if (type === "compute") {
+    const { file, hmacSecret } = event.data;
+
+    const h = hmac.create(sha256, new Uint8Array(hmacSecret));
+    const reader = file.stream().getReader();
+
+    while (true) {
+      const { done, value } = await reader.read();
+      if (done) break;
+      h.update(value);
+    }
+
+    const result = h.digest();
+    self.postMessage({ type: "result", hmac: result }, { transfer: [result.buffer] });
+  }
+};
diff --git a/src/lib/modules/crypto/hmacWorker.ts b/src/lib/modules/crypto/hmacWorker.ts
new file mode 100644
index 0000000..041eb71
--- /dev/null
+++ b/src/lib/modules/crypto/hmacWorker.ts
@@ -0,0 +1,25 @@
+import HmacWorker from "./hmac.worker?worker";
+
+export const computeFileHmac = async (file: File, hmacSecret: CryptoKey): Promise<Uint8Array> => {
+  const worker = new HmacWorker();
+  const hmacSecretRaw = await crypto.subtle.exportKey("raw", hmacSecret);
+
+  return new Promise((resolve, reject) => {
+    worker.onmessage = (event: MessageEvent<{ type: "result"; hmac: Uint8Array }>) => {
+      if (event.data.type === "result") {
+        resolve(event.data.hmac);
+        worker.terminate();
+      }
+    };
+
+    worker.onerror = (error) => {
+      reject(error);
+      worker.terminate();
+    };
+
+    worker.postMessage(
+      { type: "compute", file, hmacSecret: hmacSecretRaw },
+      { transfer: [hmacSecretRaw] },
+    );
+  });
+};
diff --git a/src/lib/modules/file/upload.svelte.ts b/src/lib/modules/file/upload.svelte.ts
index 9e9f784..ed116f5 100644
--- a/src/lib/modules/file/upload.svelte.ts
+++ b/src/lib/modules/file/upload.svelte.ts
@@ -1,13 +1,8 @@
 import ExifReader from "exifreader";
 import { limitFunction } from "p-limit";
 import { CHUNK_SIZE } from "$lib/constants";
-import {
-  encodeToBase64,
-  generateDataKey,
-  wrapDataKey,
-  encryptString,
-  createHmacStream,
-} from "$lib/modules/crypto";
+import { encodeToBase64, generateDataKey, wrapDataKey, encryptString } from "$lib/modules/crypto";
+import { computeFileHmac } from "$lib/modules/crypto/hmacWorker";
 import { Scheduler } from "$lib/modules/scheduler";
 import { generateThumbnail } from "$lib/modules/thumbnail";
 import { uploadBlob } from "$lib/modules/upload";
@@ -56,16 +51,8 @@ export const clearUploadedFiles = () => {
 
 const requestDuplicateFileScan = limitFunction(
   async (file: File, hmacSecret: HmacSecret, onDuplicate: () => Promise<boolean>) => {
-    const hmacStream = await createHmacStream(hmacSecret.secret);
-    const reader = file.stream().getReader();
-
-    while (true) {
-      const { done, value } = await reader.read();
-      if (done) break;
-      hmacStream.update(value);
-    }
-
-    const fileSigned = encodeToBase64(hmacStream.digest());
+    const hmacResult = await computeFileHmac(file, hmacSecret.secret);
+    const fileSigned = encodeToBase64(hmacResult);
     const files = await trpc().file.listByHash.query({
       hskVersion: hmacSecret.version,
       contentHmac: fileSigned,