diff --git a/frontend/src/chat/dm.ts b/frontend/src/chat/dm.ts
index 7714eb3..13450c3 100644
--- a/frontend/src/chat/dm.ts
+++ b/frontend/src/chat/dm.ts
@@ -6,7 +6,7 @@ import { importAesGcmKey, aesGcmEncrypt, aesGcmDecrypt } from "../crypto/symmetr
 import { randomBytes } from "../crypto/kdf";
 import { getCurrentKeys } from "../auth/crypto";
 import { request, websocket } from "../websocket";
-import type { FetchDMResponse, SendDMRequest, WebSocketMessage, User } from "../core/types";
+import type { FetchDMResponse, SendDMRequest, WebSocketMessage, User, DmEnvelope } from "../core/types";
 import type { Tabs } from "mdui/components/tabs";
 import { b64, ub64 } from "../utils/utils";
 
@@ -35,17 +35,7 @@ export async function sendDm(recipientId: number, recipientPublicKeyB64: string,
 	});
 }
 
-export interface DmEnvelope {
-	id: number;
-	senderId: number;
-	recipientId: number;
-	iv: string;
-	ciphertext: string;
-	salt: string;
-	iv2: string;
-	wrappedMk: string;
-	timestamp: string;
-}
+
 
 export async function fetchDm(since?: number): Promise<DmEnvelope[]> {
 	const url = new URL(`${API_BASE_URL}/dm/fetch`);
diff --git a/frontend/src/core/types.d.ts b/frontend/src/core/types.d.ts
index 8f3bf4a..b4cb17a 100644
--- a/frontend/src/core/types.d.ts
+++ b/frontend/src/core/types.d.ts
@@ -5,7 +5,6 @@
  * @version 1.0.0
  */
 
-import type { DmEnvelope } from "../chat/dm";
 
 /**
  * HTTP headers object type
@@ -169,6 +168,18 @@ export interface BackupBlob {
     blob: string;
 }
 
+export interface DmEnvelope {
+    id: number;
+    senderId: number;
+    recipientId: number;
+    iv: string;
+    ciphertext: string;
+    salt: string;
+    iv2: string;
+    wrappedMk: string;
+    timestamp: string;
+}
+
 export interface FetchDMResponse {
     messages: DmEnvelope[]
 }
diff --git a/frontend/src/crypto/symmetric.ts b/frontend/src/crypto/symmetric.ts
index 4de472b..45b85d0 100644
--- a/frontend/src/crypto/symmetric.ts
+++ b/frontend/src/crypto/symmetric.ts
@@ -11,11 +11,18 @@ export async function aesGcmEncrypt(key: CryptoKey, plaintext: Uint8Array | Arra
 }
 
 export async function aesGcmDecrypt(key: CryptoKey, iv: Uint8Array | ArrayBuffer, ciphertext: Uint8Array | ArrayBuffer): Promise<Uint8Array> {
-	// WebCrypto AES-GCM requires Uint8Array for iv and data; passing ArrayBuffer slices can break auth tag boundaries
-	const ivBytes = iv instanceof Uint8Array ? iv : new Uint8Array(iv);
-	const ctBytes = ciphertext instanceof Uint8Array ? ciphertext : new Uint8Array(ciphertext);
-	const pt = await crypto.subtle.decrypt({ name: "AES-GCM", iv: ivBytes }, key, ctBytes);
-	return new Uint8Array(pt);
+	// Normalize IV to ArrayBuffer (12 bytes for AES-GCM)
+	const ivBuf: ArrayBuffer = iv instanceof Uint8Array
+		? (iv.buffer as ArrayBuffer).slice(iv.byteOffset, iv.byteOffset + iv.byteLength)
+		: (iv as ArrayBuffer);
+
+	// Normalize ciphertext to a contiguous ArrayBuffer slice
+	const ctBuf: ArrayBuffer = ciphertext instanceof Uint8Array
+		? (ciphertext.buffer as ArrayBuffer).slice(ciphertext.byteOffset, ciphertext.byteOffset + ciphertext.byteLength)
+		: (ciphertext as ArrayBuffer);
+
+	const pt = await crypto.subtle.decrypt({ name: "AES-GCM", iv: ivBuf }, key, ctBuf);
+	return new Uint8Array(pt as ArrayBuffer);
 }
 
 export async function importAesGcmKey(rawKey: Uint8Array | ArrayBuffer): Promise<CryptoKey> {
diff --git a/frontend/src/crypto/types.d.ts b/frontend/src/crypto/types.d.ts
deleted file mode 100644
index 13bbec3..0000000
--- a/frontend/src/crypto/types.d.ts
+++ /dev/null
@@ -1,4 +0,0 @@
-declare module "tweetnacl" {
-	const nacl: any;
-	export default nacl;
-}
\ No newline at end of file