Proton CTO Bart Butler on building trust in an age of surveillance

Proton, known primarily for its encrypted email service, has expanded into a full productivity ecosystem including calendar, drive, and an AI assistant named Lumo. For Butler, the challenge lies in scaling these services to compete with Big Tech without compromising the company’s core promise. The firm relies on a unique Swiss-based corporate structure, where a foundation holds a controlling stake in Proton AG to prevent hostile takeovers or shifts in mission. This arrangement acts as a layer of defense in depth, complementing the technical reality that the company simply cannot access user data to sell or disclose it.

However, this privacy-first model faces constant friction with global law enforcement. Butler acknowledges that Proton complies with legal requests when forced by Swiss authorities, yet he maintains that the company’s jurisdiction is a calculated buffer. As European courts and regulators push for more aggressive surveillance measures, such as message scanning under the guise of child safety, Proton has signaled it would consider relocating operations to preserve its standards. For Butler, the debate over encryption backdoors is settled: there is no such thing as a backdoor that only the ‘good guys’ can use, and engineering one would fundamentally break the security of the modern internet.