Bug: "invalid_public_key_signature" error despite documented signed chat support for 1.19+

[fired]

Description

Despite Botcraft documentation stating "Signed chat system for 1.19+ versions" is supported, connections fail with
invalid_public_key_signature error on servers with enforce-secure-profile=true.

Bot successfully authenticates with Microsoft account and obtains player certificates, but gets immediately
disconnected when joining.

Environment

• Botcraft version: 1.21.10 (Windows pre-compiled binary)
• Minecraft version: 1.21.10
• Connection mode: Online (Microsoft account - authentication successful)
• Server setting: enforce-secure-profile=true

Steps to Reproduce

1. Use Botcraft 1.21.10 with online mode (Microsoft account)
2. Connect to server with enforce-secure-profile=true
3. Authentication completes successfully, player certificates obtained
4. Connection established but immediately disconnected

Logs

[INFO] Cached Minecraft token for Microsoft account still valid.
[INFO] Getting player certificates...
[INFO] Cached player certificates still valid!
[INFO] Player certificates obtained!
[INFO] Connection to server established.
[INFO] Behaviour tree changed to AFK Bot Behaviour
[INFO] Disconnect during playing with reason: {"content":{"translate":{"content":"multiplayer.disconnect.invalid_p
ublic_key_signature","name":"translate","type":"TagString"}},"name":"","type":"TagCompound"}

Expected Behavior

Since documentation mentions "Signed chat system for 1.19+ versions" support, the bot should successfully connect
and remain connected to servers with enforce-secure-profile=true.

Actual Behavior

Server rejects connection with invalid_public_key_signature error immediately after joining.

Questions

1. Is there additional configuration required to enable message signing?
2. Is this a known issue with 1.21.10 specifically?
3. Are there any special requirements for the signing to work properly?

[adepierre]

Hello, it can sometimes happen but I'm not sure why and I haven't been able to reproduce it reliably. Currently the only fix is to clear the faulty entry in the authentication cache and relog with this account. Botcraft will then fetch the updated keys instead of thinking the cached ones are still valid. An alternative is to manually set all expires_date in the cache file to 0 when this happens to force a refresh.

[fired]

I tried clearing the cache as you suggested, but it still fails with the signature error.

Here is the code I'm trying to get working. Does anything look off/wrong with this?

MultiAFK.cpp

#include <botcraft/Game/ConnectionClient.hpp>
#include <botcraft/Utilities/Logger.hpp>
#include <thread>
#include <vector>
#include <memory>
#include <iostream>

int main(int argc, char* argv[])
{
    try
    {
        std::string address = "localhost:25565";
        std::string login = "";
        int bot_count = 1;
        bool online_mode = false;

        // Parse command line arguments
        if (argc < 2)
        {
            std::cout << "Usage: " << argv[0] << " <options>\n";
            std::cout << "Options:\n";
            std::cout << "    --address <IP:PORT>  : Address of the server to connect to (default: localhost:25565)\n";
            std::cout << "    --login <login>      : Microsoft account email for online mode, or empty \"\" for cached credentials\n";
            std::cout << "    --count <number>     : Number of bots to launch (default: 1)\n";
            std::cout << "    --online             : Use online mode with Microsoft account (only 1 bot supported)\n";
            std::cout << "    --offline            : Use offline mode with bot names (Bot_0, Bot_1, etc.)\n";
            return 0;
        }

        for (int i = 1; i < argc; ++i)
        {
            std::string arg = argv[i];
            if (arg == "--address" && i + 1 < argc)
            {
                address = argv[++i];
            }
            else if (arg == "--login" && i + 1 < argc)
            {
                login = argv[++i];
            }
            else if (arg == "--count" && i + 1 < argc)
            {
                bot_count = std::stoi(argv[++i]);
            }
            else if (arg == "--online")
            {
                online_mode = true;
                bot_count = 1; // Only 1 bot supported in online mode
            }
            else if (arg == "--offline")
            {
                online_mode = false;
            }
        }

        Botcraft::Logger::GetInstance().SetLogLevel(Botcraft::LogLevel::Info);
        Botcraft::Logger::GetInstance().SetFilename("");
        Botcraft::Logger::GetInstance().RegisterThread("main");

        std::vector<std::shared_ptr<Botcraft::ConnectionClient>> bots;
        std::vector<std::thread> bot_threads;

        LOG_INFO("Launching " << bot_count << " bot(s) in " << (online_mode ? "ONLINE" : "OFFLINE") << " mode");

        for (int i = 0; i < bot_count; ++i)
        {
            auto bot = std::make_shared<Botcraft::ConnectionClient>();

            std::string bot_login = online_mode ? login : "Bot_" + std::to_string(i);

            LOG_INFO("Starting bot " << i << ": " << (online_mode ? "Microsoft Account" : bot_login));

            bot_threads.emplace_back([bot, address, bot_login]() {
                try
                {
                    bot->Connect(address, bot_login);

                    while (!bot->GetShouldBeClosed())
                    {
                        std::this_thread::sleep_for(std::chrono::milliseconds(100));
                    }
                }
                catch (std::exception& e)
                {
                    LOG_ERROR("Bot exception: " << e.what());
                }
            });

            bots.push_back(bot);

            // Small delay between bot launches to avoid overwhelming the server
            std::this_thread::sleep_for(std::chrono::seconds(2));
        }

        LOG_INFO("All " << bot_count << " bots launched. Press Ctrl+C to stop.");

        // Wait for all bots
        for (auto& thread : bot_threads)
        {
            if (thread.joinable())
            {
                thread.join();
            }
        }

        return 0;
    }
    catch (std::exception& e)
    {
        LOG_FATAL("Exception: " << e.what());
        return 1;
    }
}

Usage Examples

Online mode (1 bot with Microsoft account):

MultiAFKExample.exe --address server.com:25565 --online --login ""

Offline mode (5 bots):

MultiAFKExample.exe --address server.com:25565 --offline --count 5

I'm using the precompiled DLLs from the 1.21.10 Windows release. The official 3_SimpleAFKExample.exe works fine, but anything I compile fails with multiplayer.disconnect.invalid_public_key_signature when trying to connect to a server.

[adepierre]

Thanks for the code. I'll see if I can reproduce on my side. It's weird that the AFK bot can connect using the same credentials/key and not your code 🤔

[adepierre]

Ok I managed to reproduce the issue once (logging in with the account, fetching all info including certificates from the server and getting the "invalid signature" once connected).
However, everything started to work everytime after manually setting all the expires_date to 0 in the credentials json file.
Now your case is even weirder as it seems that the same credentials work with the AFK example but not your code, while your code doesn't seem to do anything different regarding authentication. Maybe you could try to replace your code with the example and recompile to know if the issue comes from the compilation process or the code itself, but I really don't know how it could behave differently between both versions assuming botcraft is linked properly for compilation.

I'll try to dig deeper but I'll have to let my tokens expire again to try reproducing again the issue so I don't expect fast progress on this issue unfortunately.

[adepierre]

I think I found the root cause of the issue. I'll try to fix it in the coming days so it can be included in November release (probably this week end).