Charles Guillemet is Ledger’s Chief Technology Officer (CTO). He joined the company in 2017 when he started to build Ledger’s renowned security department, the Donjon. As a teenager, Charles loved hacking computers, a hobby that eventually became his profession. Before joining Ledger, he spent 10 years in the Cryptography & Hardware Security sector, starting with Tiempo, an innovative start-up where he designed EAL5+ secure integrated circuits. He then worked as Technical Manager in an Information Technology Security Evaluation Facility (ITSEF) at the CEA, the French Research Organization. Under Charles’ technology leadership, Ledger has become a world-leading security platform in crypto, safeguarding 20% of digital assets globally.