fix: use base64url to encode the migration param

bot/main.py

@@ -19,14 +19,18 @@
 
 
 async def migrate(update: Update, context: ContextTypes.DEFAULT_TYPE):
-    data = urllib.parse.quote_plus(update.message.web_app_data.data)
+    data = update.message.web_app_data.data
 
-    qr = qrcode.make(f"otpauth-migration://offline?data={data}")
+    urlencoded = urllib.parse.quote_plus(data)
+
+    qr = qrcode.make(f"otpauth-migration://offline?data={urlencoded}")
     qr_bytes = BytesIO()
     qr_bytes.name = "image.png"
     qr.save(qr_bytes, "png")
     qr_bytes.seek(0)
 
+    data = data.replace("+", "-").replace("/", "_").replace("=", "")
+
     url = f"{app_tg}?startapp={data}"
 
     await context.bot.send_photo(chat_id=update.effective_chat.id,

src/migration/import.ts

@@ -7,9 +7,17 @@ export default function decodeGoogleAuthenticator(uri: string): Account[] | null
     if (!uri.startsWith("otpauth-migration://offline")) return null;
 
     const url = new URL(uri);
-    const dataParam = url.searchParams.get("data");
+    let dataParam = url.searchParams.get("data");
     if (!dataParam) return null;
 
+    // Convert from base64url
+    dataParam = dataParam
+        .replace(/-/g, '+')
+        .replace(/_/g, '/');
+
+    const pad = dataParam.length % 4;
+    dataParam += "=".repeat(pad);
+
     const buffer = Uint8Array.from(atob(dataParam), (c) => c.charCodeAt(0));
 
     let payload;