German police monitor WhatsApp, Signal and Telegram without breaking encryption
German authorities secretly connect police devices to the accounts of suspects on WhatsApp, Signal and Telegram. The method is now at the centre of legal challenge.
How German police read encrypted messages
German law enforcement authorities use a surveillance technique on applications such as WhatsApp, Signal and Telegram, without needing to breach end-to-end encryption or install spyware on users' devices. Dnews.gr reports the publication by Cybernews, which cites documents revealed by the German digital rights publication Netzpolitik.
The technique exploits a completely lawful function of the applications: the ability to link an account with a second device. Services such as WhatsApp Web and Signal Desktop allow users to receive messages on a computer. The authorities exploit precisely this capability, connecting a computer under their control to the target's account.
Once the police device is recognised as authorised, incoming messages are automatically delivered to it as well. According to the documents, the German Customs Service began testing the method in late 2023.
How they gain access to the account
To activate the connection, authorities initially need access to the account. This can be achieved through physical access to the mobile phone, by intercepting authentication codes via an approved phishing attack, or by intercepting SMS as part of telephone surveillance. In the case of Signal, connecting a second device can provide access even to messages from the previous 45 days.
A characteristic case of the method's application is found in March 2022. Police secretly connected to the Telegram account of a suspect for drug trafficking in Lower Saxony. The suspect noticed the access a few hours later, but the authorities had already copied his message archive. According to the documents, the practice acquired official status in August 2025, after the competent authorities argued that it had produced "significant investigative successes" in cases of serious and organised crime.
The case of witnesses who became surveillance targets
Particular discussion has been provoked by a 2020 case in which the couple who surrendered their mobile phones were not suspects but were being examined as witnesses regarding their daughter. While the devices were in the hands of the police, WhatsApp Web was secretly activated and the accounts were connected to a computer of the Federal Crime Service (BKA).
This connection could potentially have allowed the authorities to read new messages even after the mobile phones were returned, to see synchronised older conversations and contacts, and to send messages appearing to come from the individuals themselves. The method, however, does not provide the capability to monitor WhatsApp voice calls, nor access to the camera, microphone, conventional SMS or other applications on the device.
Legal challenge from the Federal Court
The method is now at the centre of legal challenge in Germany. In January, the Federal Court ruled that secret connection to Telegram accounts in this manner constitutes a form of surveillance, rejecting a previous interpretation of the relevant legislation.
Source: Google News GR — Crime (el)