YHK - yet another hacker news clone

Tapo (Rust/Python library) now speaks TP-Link's TPAP protocol

51 points faithraven 1 hour ago 10 comments

faithraven 1 hour ago | parent

Author here. tapo is an unofficial Rust client library for TP-Link Tapo devices (plugs, lights, hubs, cameras), with a Python wrapper built on the same crate. It is not affiliated with TP-Link.

The short version: since late 2025, firmware updates have made Tapo devices refuse third-party clients unless you turn on a "Third-Party Compatibility" switch in the Tapo app. The switch works by bringing back the older login, KLAP. With it off, devices speak an undocumented protocol called TPAP, which logs in with SPAKE2+ (RFC 9383). The library now speaks TPAP, so the switch can stay off.

The part I found most interesting is the security difference. A recorded KLAP login can be used to test password guesses offline. With SPAKE2+ it can't, and learning the password later doesn't decrypt sessions captured earlier. So the "compatibility" switch is really a security downgrade, and TP-Link's own FAQ says enabling it "may reduce the security of your devices".

Not everything works with the switch off yet: some cameras, such as a C210 on firmware 1.5.2, still need it on.

Happy to answer questions about the protocol work or the library.

mindslight 35 minutes ago | parent

I have a handful of old TP-Link wifi switch devices, but I haven't kept up on the play by play developments. I just know at some point newer ones stopped working with that access method (and I haven't bought any since).

Is KLAP that old local-network UDP protocol with "XOR encryption" ? Or is that something else?

Does using TPAP with your library still require connecting the devices to their "cloud" (warning: surveillance!) ? Or does your library effectively restore the local-only workflow of never allowing the devices Internet access, and controlling them locally ?

tclancy 34 minutes ago | parent

This is awesome, thanks for the work. I wish I'd come across it sooner.

pkilgore 1 hour ago | parent

I was always taught: Read good books, that's how you'll write.

I don't even really care AI or human if its written like this. I would rather do anything else than continue reading.

IshKebab 1 hour ago | parent

Hard to disagree. I'm interested, but... the writing sucks.

And there's no excuse now anyway the latest Opus/Astra models are actually tolerable. Use those if you must.

teravor 48 minutes ago | parent

since GLM 5.2 (perhaps even earlier?) it has been remarkably easy to reverse engineer any closed protocol you want as long as you have a binary. previously, it required so much manual effort as to simply not be worth it 95% of the time.

now all you need is IDA or Ghidra MCP, a binary and some vague sloppy instructions.

some more recent models even started instrumenting a running binary (when possible) to enumerate the protocol without being explicitly instructed to, which is even better.

faithraven 40 minutes ago | parent

Without admitting to anything, I was surprised by how little time it took to add support for the new protocol to the library. And I didn't even need an MCP server.

Retr0id 32 minutes ago | parent

You don't even need an MCP, I just let the agent write scripts for headless ghidra. The MCPs are fragile and there isn't a whole lot of knowledge about how to use them in the training datasets, whereas there are plenty of ghidra scripts (and proper docs for the APIs).

teravor 18 minutes ago | parent

    > there isn't a whole lot of knowledge about how to use them in the training datasets
if you include a SKILL.md for the MCP (or just dump it into the prompt) it's not a problem.

I don't use Ghidra but IDA Pro MCP works extremely well for me for all manner of tasks. for example, some software likes to call home for license checking (and I wish to run it with networking denied to it). it no longer does.

Retr0id 2 minutes ago | parent

Sure, you can do that, but in my experience it's usually best to let agents do the things they already know how to do.