The debate on the privacy of digital communications in Europe is at a critical stage. Under the name "Chat Control" (or CSAR regulation) lies a legislative project that, with the commendable goal of preventing the spread of illegal material, risks undermining the foundations of cybersecurity for millions of citizens: end-to-end encryption (E2EE).

Proponents of control believe it is possible to reconcile public safety and message encryption. Security experts and cryptographers, on the other hand, warn that there cannot be "secure but accessible to authorities" encryption: inserting an access key for the state means weakening the barrier against any malicious actor.

Two Models in Comparison

Currently, two different regulatory and technological approaches coexist in the European digital landscape:

  • Voluntary scans by major providers: Many platforms that do not use end-to-end encryption by default analyze files uploaded to their servers to compare them with databases of known digital fingerprints (hashes). This system falls under a temporary exemption (extended until 2028) and does not affect the security of users' devices.
  • Mandatory monitoring (Chat Control 2.0): The legislative proposal aims to impose scanning obligations even on encrypted messaging applications. Unable to read messages in transit on servers, the only technical solution would be to scan them directly on the sender's smartphone before sending.

The Dead End of Client-Side Scanning

Scanning on the user's device (client-side scanning) effectively turns the phone into a local surveillance agent. Besides raising enormous constitutional doubts about the presumption of innocence, this method introduces structural vulnerabilities in operating systems, exposing them to external attacks and false positives generated by the detection algorithms themselves.

Privacy-focused providers (such as Signal or Proton) have already declared that they would prefer to withdraw their services from the European market rather than accept the insertion of backdoors that compromise the promise of privacy made to their users.

Strategies for Defending Privacy

The protection of corporate and personal communications requires awareness and the adoption of appropriate technical solutions. For those who need maximum privacy, the viable paths look towards decentralization: the use of open protocols (such as Matrix or XMPP with OMEMO encryption) installed on self-managed private servers, outside the control and regulatory constraints imposed on large centralized commercial platforms.