diff --git a/src/lib/modules/crypto/sha.ts b/src/lib/modules/crypto/sha.ts
index 61c2ed7..5e9e3fa 100644
--- a/src/lib/modules/crypto/sha.ts
+++ b/src/lib/modules/crypto/sha.ts
@@ -1,5 +1,5 @@
-import { hmac } from "@noble/hashes/hmac.js";
-import { sha256 } from "@noble/hashes/sha2.js";
+import HmacWorker from "$workers/hmac?worker";
+import type { ComputeMessage, ResultMessage } from "$workers/hmac";
 
 export const digestMessage = async (message: BufferSource) => {
   return await crypto.subtle.digest("SHA-256", message);
@@ -18,10 +18,24 @@ export const generateHmacSecret = async () => {
   };
 };
 
-export const createHmacStream = async (hmacSecret: CryptoKey) => {
-  const h = hmac.create(sha256, new Uint8Array(await crypto.subtle.exportKey("raw", hmacSecret)));
-  return {
-    update: (data: Uint8Array) => h.update(data),
-    digest: () => h.digest(),
-  };
+export const signMessageHmac = async (message: Blob, hmacSecret: CryptoKey) => {
+  const worker = new HmacWorker();
+  const stream = message.stream();
+  const hmacSecretRaw = new Uint8Array(await crypto.subtle.exportKey("raw", hmacSecret));
+
+  return new Promise<Uint8Array>((resolve, reject) => {
+    worker.onmessage = (event: MessageEvent<ResultMessage>) => {
+      resolve(event.data.result);
+      worker.terminate();
+    };
+
+    worker.onerror = ({ error }) => {
+      reject(error);
+      worker.terminate();
+    };
+
+    worker.postMessage({ stream, key: hmacSecretRaw } satisfies ComputeMessage, {
+      transfer: [stream, hmacSecretRaw.buffer],
+    });
+  });
 };
diff --git a/src/lib/modules/file/upload.svelte.ts b/src/lib/modules/file/upload.svelte.ts
index 9e9f784..d066d4f 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 "$lib/modules/crypto";
+import { signMessageHmac } from "$lib/modules/crypto";
 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 signMessageHmac(file, hmacSecret.secret);
+    const fileSigned = encodeToBase64(hmacResult);
     const files = await trpc().file.listByHash.query({
       hskVersion: hmacSecret.version,
       contentHmac: fileSigned,
diff --git a/src/workers/hmac.ts b/src/workers/hmac.ts
new file mode 100644
index 0000000..1b20235
--- /dev/null
+++ b/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] });
+};
diff --git a/svelte.config.js b/svelte.config.js
index 4ffc844..6562b93 100644
--- a/svelte.config.js
+++ b/svelte.config.js
@@ -8,6 +8,7 @@ const config = {
     adapter: adapter(),
     alias: {
       $trpc: "./src/trpc",
+      $workers: "./src/workers",
     },
   },
 };