The International Telecommunication Union (ITU) is organizing the Fifth ITU-T X.509 Day taking place on 12 May 2026 from 9h00 to 18h00 CEST at ITU Headquarters, in Geneva, Switzerland. .
ITU-T X.509 is the common global language for public key infrastructure (PKI) and privilege management infrastructure (PMI), providing a framework for digital certificates and trust management.
First published in 1988, the result of the collaboration between CCITT and ISO/IEC, ITU-T X.509 has since seen nine editions (the most recent approved in October 2019), with a tenth edition under study to address emerging needs such as quantum-safe cryptography. X.509’s certificate and CRL structures, with their extensibility, underpin secure transactions in business-to-business (B2B), business-to-consumer (B2C), and government-to-citizen (G2C) interactions. This widely recognized standard provides a reliable foundation for a wide range of industries – from agriculture and finance to healthcare, transport, and utilities – making it indispensable to businesses, consumers, and governments worldwide.
With over 38 years of successful implementation, X.509 is truly used everywhere and across all regions, enabling fundamental interoperability and security across countless applications. Since 2022 ITU has organized four times this annual ‘ITU-T X.509 Day’ event. Notably, the theme of the fourth X.509 Day event highlighted “X.509 in 2025: Navigating the post-quantum era”, underscoring the growing importance of quantum-safe credentials.
Since then, progress in standardizing post-quantum cryptography and new developments in decentralized identity and AI trust frameworks have further accelerated. The Fifth ITU-T X.509 Day event will review the latest advances, address emerging challenges (such as preparing for quantum computers and decentralized PKI), and showcase real-world adoption of X.509 across sectors.
The objectives of this fifth ITU-T X.509 Day (2026) will be to :
- Review recent progress of ITU-T X.509 in relevant groups since the 4th X.509 Day, including updates from ongoing work and collaborations.
- Assess post-quantum cryptography (PQC) readiness in the X.509 ecosystem
- Explore developments in decentralized PKI (DPKI) and trust models
- Strengthen trust in AI-enabled systems by leveraging X.509
- Highlight how X.509 certificates enable interoperability of digital identities across borders and sectors
- Showcase real-world adoption across sectors through case studies
- Identify future development directions for ITU-T X.509 and opportunities for collaboration
Target audienceParticipation was free of charge and open to all interested stakeholders including ITU Member States, Sector Members, Associates and Academic Institutions and to any individual from a country that is a member of ITU and who wished to contribute to the work. The event was organised in English only.
RegisterRemote Participation: Connect to the MyWorkspace platform using the same ITU user account with which you registered for the meeting. You can launch the remote session by clicking the JOIN button from 30 minutes prior to the start of the meeting.
