diff --git a/web/database/utils/worker-crypto-utils.js b/web/database/utils/worker-crypto-utils.js
new file mode 100644
--- /dev/null
+++ b/web/database/utils/worker-crypto-utils.js
@@ -0,0 +1,60 @@
+// @flow
+
+import type { AesGcmParams, Crypto, CryptoKey } from './crypto-types.js';
+
+declare var crypto: Crypto;
+
+const ENCRYPTION_ALGORITHM = 'AES-GCM';
+
+type EncryptionResult = {
+  iv: BufferSource,
+  cipher: ArrayBuffer,
+};
+
+function generateCryptoKey(): Promise<CryptoKey> {
+  return crypto.subtle.generateKey(
+    {
+      name: ENCRYPTION_ALGORITHM,
+      length: 256,
+    },
+    false,
+    ['encrypt', 'decrypt'],
+  );
+}
+
+function generateIv(): BufferSource {
+  return crypto.getRandomValues(new Uint8Array(12));
+}
+
+async function encrypt(
+  data: ArrayBuffer,
+  key: CryptoKey,
+): Promise<EncryptionResult> {
+  const iv = generateIv();
+  const params: AesGcmParams = {
+    name: ENCRYPTION_ALGORITHM,
+    iv: iv,
+  };
+  const cipher = await crypto.subtle.encrypt(params, key, data);
+  return {
+    cipher,
+    iv,
+  };
+}
+
+async function decrypt(
+  cipher: ArrayBuffer,
+  key: CryptoKey,
+  iv: BufferSource,
+): Promise<ArrayBuffer> {
+  return crypto.subtle.decrypt(
+    {
+      name: ENCRYPTION_ALGORITHM,
+      iv,
+    },
+    key,
+    cipher,
+  );
+}
+
+export { generateCryptoKey, encrypt, decrypt };