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Citadel: trusted messaging for professionals

Instant messaging services are hugely popular today. They're a great way to communicate simply and directly, but professionals can’t trust them with sensitive information because they're not secure. The Citadel app, operated end-to-end by Thales, fills this gap.

In the course of their work, managers, engineers, auditors, lawyers, public officials and other professionals routinely handle sensitive issues and information that needs to be kept confidential and secure. Yet in today’s interconnected world, these professionals expect to benefit from the same kind of convenience and mobility as everyone else.

Convenience or security?

For voice and video calls, texting and file sharing with friends, instant messaging apps on a mobile phone are incredibly convenient. But in a professional context, where information may be sensitive, they raise a number of questions. Could my communications be intercepted? Where is my data stored? Who can access it? Does the system offer end-to-end security, now and forever?

With Citadel, the trusted messaging app from Thales, professionals no longer have to choose between convenience and security — they can have both!

Trust makes all the difference

Easy to install on any smartphone, Citadel offers the same recognisable functionality and usability as most consumer messaging apps. It offers secure messaging services on a smartphone or computer, plus a host of related functions, including end-to-end encrypted voice calls and file sharing. It's just as easy to use as the most well-known messaging apps — but the difference with Citadel is trust.

Designed exclusively for professionals, the application can only be used with a company email address and features the same built-in encryption system used by senior officials in the French government and 50 NATO countries. Thales operates every link in the chain, in France, including data storage and security management, and guarantees high availability. Advanced access control and permissions management functions are available to control who takes part in discussion groups and has access to stored documents.


  • Professional email address mandatory
  • Robust encryption of voice and video calls
  • Data storage and security by Thales in France
  • Advanced management of discussion groups
  • Intuitive interface
  • App opens automatically on incoming calls
  • Available in the iOS and Android stores

Confidentiality and connectivity reconciled

To offer a solution that's both fully functioned and fully trusted, a key question needed to be answered: what’s the point of an instant messaging service, which is viral by nature, if security considerations mean that professionals can only use it to connect with a few members of their own organisation? Thales drew on the talent and know-how of its system engineers to design a unique architecture, in which each organisation's data is completely segregated from the data of other organisations. When users in different organisations communicate or share files, only that data is synced.

With Citadel, professionals finally have a convenient messaging app that lets them communicate quickly and efficiently however confidential the topic of conversation may be.