Chat Control: two specialists sound the alarm over a major risk to privacy

The debate around the European Chat Control project continues to stir up the scene of cybersecurity and privacy protection. Despite the apparent withdrawal of the vote on this controversial regulation, the compromise found by the Council of the European Union raises profound questions. Two renowned French specialists, Renaud Ghia from Tixeo and Achraf Hamid from Mailinblack, warn of a major risk: this compromise could actually normalize an insidious form of surveillance of private communications, particularly through the establishment of a vague “risk mitigation” mechanism that weakens the robust protection mechanisms of personal data and encryption.

While end-to-end encryption (E2EE) is currently seen as an essential red line to guarantee the confidentiality of digital exchanges, this European compromise seems to open a breach. Although the removal of mandatory message scanning is presented as progress, many actors warn about the establishment of mitigation obligations that could encourage platforms to analyze content before encryption, which is technically contradictory to the principle of E2EE.

At the heart of the controversy, the so-called client-side scanning (CSS) technique plays a key role. This method involves scanning messages directly on the device before they are encrypted, thereby exposing data to increased risks. According to experts, this vulnerability could be exploited by malicious actors, advanced cyber-attack groups, as well as states, while exacerbating the risks of unjustified large-scale communication control.

The issue goes beyond the simple technical aspect, impacting both citizens and businesses, especially those with regulated activities. For example, in a context of growing use of personal devices (BYOD) in professional environments, the threat becomes structural, harming confidentiality but also European digital sovereignty.

In this article, we decode in detail the contours of this Chat Control compromise, the arguments of specialists warning of its privacy dangers, as well as the challenges for the future of encryption, confidentiality, and the legitimate fight against illegal online content.

The Chat Control compromise: between reassuring appearance and underlying risks for confidentiality

The Council of the European Union recently published a compromise concerning the Chat Control regulation, which initially seemed like a sign of progress. Indeed, the official removal of mandatory scanning of private messages was hailed as a major victory by some political and media actors.

However, this feeling of relief is far from shared by all. Renaud Ghia, president of Tixeo, a company specialized in secure solutions, warns against an illusion effect. According to him, the disappearance of mandatory scanning hides an extension of mitigation requirements, as provided in article 4 of the text. Yet, these measures, as currently formulated, leave a wide margin for interpretation regarding the methods employed.

To summarize the critical points of the compromise, here is a list of the main aspects highlighted by the specialists:

• Removal of mandatory scanning of messages, but maintaining a legal framework encouraging preventive analysis of content before encryption.
• Mitigation measures with vague outlines which can be interpreted as a disguised obligation.
• Possibility for platforms to conduct voluntary scanning of messages, including in end-to-end encrypted messaging services.
• Normalization of preventive surveillance of private communications which could become generalized to other purposes.

This paradox means that the system will appear technically less aggressive but will actually exert increasing pressure on the confidentiality of electronic exchanges. The perverse effect is particularly worrisome because it plays on regulatory fatigue and society’s weariness regarding complex technical debates.

Compromise element	Reassuring appearance	Risk / criticism
Removal of mandatory scanning	Less explicit surveillance	Encouragement of uncontrolled voluntary scans
Mitigation measures	Targeted actions against illegal content	Vague definition and potentially broad application
Effect on privacy	Fewer visible infringements	Normalized risk of prior message analysis
Impact on encryption	Officially maintained	Vulnerability induced by client-side scanning

This framework continues to provoke a strong alert among many actors who fear a drift towards an extensive surveillance model under the guise of fighting child pornography. The idea that protecting minors justifies further deep intrusion amplifies the debate on the acceptable scope of measures.

The technical dangers of client-side scanning: a flaw in end-to-end encryption

The Chat Control compromise indirectly reintroduces a highly controversial technical device: client-side scanning (CSS). Unlike centralized analyses on servers, this technique operates directly on users’ devices, where messages are processed in clear text before being encrypted and sent.

This operation poses a fundamental contradiction with the very principle of end-to-end encryption (E2EE), which guarantees that only the sender and recipient can access the content. Indeed, with CSS, a software or hardware scanner will have access to the messages in clear text, potentially exposing sensitive personal data.

Renaud Ghia explains that this process introduces a structural vulnerability, because:

• Confidentiality is compromised at the device level, where the message should remain protected.
• The attack surface increases significantly, offering hackers more targets.
• This model requires integrating an analysis engine into each device, fragmenting the security perimeter.

For his part, Achraf Hamid details several concrete risks linked to this approach:

• Potential insertion of malware capable of collecting clear messages before encryption.
• Supply chain attacks during updates of the scanning module, creating widespread backdoors.
• Manipulation of signature databases used to detect content, potentially leading to arbitrary censorship of political or journalistic documents.
• Targeted surveillance and censorship through abuse of the detection system.

Risks related to client-side scanning	Description	Possible consequences
Exposure of clear messages	Local analysis before encryption	Breaches in message confidentiality
Embedded malware	Malicious software grafted onto the scanner	Massive theft of personal data
Supply chain attacks	Corrupted updates of the detection module	Backdoors for mass espionage
Manipulation of detection lists	Arbitrary addition of signatures	Political censorship and information suppression

Beyond a mere tool, this technology raises the question of the fundamental respect for communication secrecy. Paradoxically, an initiative designed to strengthen security against certain crimes could globally weaken digital confidentiality.

Concrete impacts for businesses and institutions: a double threat to security and sovereignty

The Chat Control project does not only concern individuals’ private conversations. Public and private organizations are also directly targeted by the mitigation measures, raising significant questions.

Renaud Ghia warns about the increased vulnerability of so-called “critical” businesses:

• Public and governmental institutions.
• Sensitive sectors such as health, finance, and defense.
• Structures regulated by standards such as GDPR, NIS2, or DORA.

An aggravating phenomenon is the widespread use of BYOD (“Bring Your Own Device”), where employees use their personal devices to access professional resources. This mixing of environments facilitates the exposure of sensitive exchanges to unwanted analysis, compromising confidentiality and privacy protection of businesses.

The risks involved are multiple:

• Loss of regulatory compliance, especially regarding data protection.
• Potential leaks of strategic and intellectual property data.
• Damage to European digital sovereignty, with increased dependence on foreign technologies.

Organization categories	Exposure to Chat Control risk	Consequences
Public institutions	Exchange of sensitive data within administration	Damage to national security
Critical businesses	Internal communication, industrial secrets	Loss of confidentiality and regulatory impact
Organizations subject to GDPR/NIS2/DORA	Enhanced compliance obligations	Legal and financial risk

As a result, Europe could paradoxically weaken its own actors while promoting less privacy-respecting standards, amplifying a distortion of competition in favor of American tech giants. This trend particularly worries European secure service providers, already committed to defending a strict encryption policy.

Contested effectiveness and potential abuses: why Chat Control does not protect the most vulnerable

Beyond the risks to confidentiality, experts emphasize that the planned measures would be poorly effective in achieving their primary goal, namely the fight against online child exploitation.

According to Achraf Hamid, criminals already have sophisticated and decentralized tools to circumvent surveillance, including self-hosted services or closed platforms, making them virtually invisible to imposed scanners.

At the same time, this system would generate:

• A significant amount of false positives, saturating investigation resources.
• An unbearable workload for analysis teams.
• Massive and unjustified intrusion into the privacy of law-abiding citizens.

The benefit-to-drawback ratio therefore seems unfavorable, while the Chat Control compromise would generate a high cost, both financially and humanly, without proven effectiveness against real threats.

Moreover, the role of the European Parliament is crucial. It still holds significant decision-making power to:

• Block the adoption of the regulation as it stands.
• Demand a formal ban on client-side scanning.
• Guarantee the preservation of end-to-end encryption and limit surveillance to strictly regulated and judicial cases.

The choice facing European decision-makers is therefore decisive: to preserve robust confidentiality while respecting fundamental rights, or to yield to expansive preventive surveillance that weakens current safeguards.

Towards effective protection without compromising privacy: possible alternative paths

Far from being inevitable, the fight against online abuse can rely on technological options respectful of fundamental rights. Mailinblack thus advocates concentrated efforts on specific measures:

• Strict refusal of any obligation or strong incentive to perform client-side scanning.
• Implementation of targeted measures fully controlled by the judiciary, with transparency and verification mechanisms.
• Promoting statistical transparency to ensure public control of practices.
• Massive investment in prevention, specialized investigations, and innovative privacy-by-design technologies, such as secure multiparty computation (MPC) or decentralized local analyses.

Tixeo shares this view and concludes that the uncompromising preservation of end-to-end encryption is the sine qua non condition to guarantee collective digital security. Any derogation introduces a structural flaw, whose consequences would be vast and irreversible.

Possible approaches	Advantages	Limitations
Client-side scanning	Preventive control of content	Weakening of confidentiality and risks of abuses
Targeted judicial measures	Framed, proportionate, and transparent control	Potential delay in response, need for human resources
Privacy-by-design technologies	Security respectful of privacy	Ongoing innovation, requiring investments

The debate around Chat Control reveals the dilemma faced by modern democracies: how to protect society without sacrificing its essential freedoms. The vigilance of specialists, tech actors, and citizens remains more necessary than ever so that digital confidentiality is not the first victim of this battle.