How to make a private Telegram bot accessible only by its owner?

Question

You can do this in setting, you need to check by yourself, just exit program if .message.from.id not equal to yours.

You can disable join group via /setjoingroup, but you can't invite bot to group either.

There is nothing you can do with BotFather. the only way is to check it inside your code.

You can check for the chat id (9 digit number) in your code.

For example, if you use this wrapper to create bot, you can use update.message.chat_id to get chat id. You can also check for the first name (update.message.from_user.first_name) and last name (update.message.from_user.last_name).

I started working a few weeks ago on telegram's bots. For that I've read in the specifications there is no way to create a private bot from botfather. The only way is using a custom command like /password to send a password to the bot and then keep the chat id of the client (when password is correct of course ...). Your bot need to accept commands only from memorized/autentificated chat id as you would do it in a classical way for any other application.

There's another option described in the telegram docs.

You can use a deeplink to get a unique key from the link and secure your bot. Denying access in your code to anyone who does not have the key.

From the docs:

1. Create a bot with a suitable username, e.g. @ExampleComBot
2. Set up a webhook for incoming messages
3. Generate a random string of a sufficient length, e.g. $memcache_key = "vCH1vGWJxfSeofSAs0K5PA"
4. Put the value 123 with the key $memcache_key into Memcache for 3600 seconds (one hour)
5. Show our user the button https://t.me/ExampleComBot?start=vCH1vGWJxfSeofSAs0K5PA
6. Configure the webhook processor to query Memcached with the parameter that is passed in incoming messages beginning with /start. If the key exists, record the chat_id passed to the webhook as telegram_chat_id for the user 123. Remove the key from Memcache.
7. Now when we want to send a notification to the user 123, check if they have the field telegram_chat_id. If yes, use the sendMessage method in the Bot API to send them a message in Telegram.