On September 19th 2023, we announced PQXDH: the first step in advancing quantum resistance for the Signal Protocol. Signal was the first mainstream messaging app to take this step — adding an important layer of protection against the threat of a quantum computer being built in the future that is powerful enough to break current encryption standards.
It's been over a year and half since PQXDH support was first added to Signal. To help ensure that everyone is benefiting from these improvements, Signal will soon begin requiring PQXDH support in order to continue using the service.
Why am I seeing this banner in Signal Desktop
Your account falls into a rare category:
- Your account’s primary device (the Android or iOS device that you originally used to register for Signal) hasn't been updated and hasn't connected to the Signal service for more than a year.
- One or more of your linked devices (like Signal Desktop) are still actively using Signal and connecting to the service.
- Your account’s primary device doesn't support PQXDH.
What do I need to do?
Under ideal circumstances, the process itself should be simple and straightforward:
- Find the phone that you originally used to register for Signal.
- Turn the phone on and install the latest Signal update (e.g. from the App Store or Play Store). Signal releases expire after 90 days, so charging a phone that has been sitting in a drawer and immediately trying to launch an old version of Signal won't work.
- Launch the latest Signal update on that phone and let it connect to the service. Please note that you are likely to see a variety of errors in different chat threads. Your primary device has been disconnected from the Signal service for a very long time, and may not be able to gracefully catch up with everything that it has missed.
- Keep Signal open on the phone for a few minutes.
- Close and relaunch Signal Desktop. If your phone was successfully able to update and connect to the service, you should no longer see the banner.
What if I don't do this, or I no longer have access to that phone, or I have since uninstalled Signal from the original primary device?
Your account will be deactivated, and you will need to reinstall and register for Signal using an up-to-date version of the application.
How can I ensure this doesn't happen again?
Please periodically launch Signal on your phone and ensure that it remains up-to-date. Some features can only be enabled if every device on your account supports the latest updates and improvements, and this simply isn't possible when the primary device isn't used.
Why do I need to do this from my primary device/phone?
For your Signal account to support PQXDH, all of the individual devices linked to your account must support PQXDH. Every Signal account must have a primary device. Your primary device is always associated with your Signal account and cannot be removed from your account, even if you do not use it regularly. Every device linked to a Signal account has its own set of encryption keys, and one device cannot generate new encryption keys for another device. Because your primary device cannot be removed from your account, you must reactivate your primary device so that it can generate PQXDH encryption keys and the other devices associated with your account can benefit from the protection offered by PQXDH.
Why does this matter?
Falling behind on the latest features and improvements affects everyone you talk to as well. Because your account doesn't currently support PQXDH, nobody else can exchange messages with you using the updated protocol even if their accounts and devices are up-to-date.
Although it’s something that most other apps haven't even started working on yet, Signal has been leading the way in incorporating new approaches to defend against the threat of a future quantum computer. Enforcing PQXDH support, without any legacy fallback methods, will allow us to continue building on these efforts and help protect the people you care about.
We are grateful for your understanding, and we apologize for any inconvenience.