Gilles Brassard
The Montréal cryptographer who took Stephen Wiesner's quantum money and, with Charles Bennett, turned it into a usable key exchange.
Brassard and Bennett met in 1979 and started from Wiesner's unpublished idea of money that can't be forged because quantum states can't be copied. The result was BB84 (1984). Brassard also contributed to privacy amplification, the technique that shrinks a partly eavesdropped key into a shorter one the eavesdropper knows almost nothing about — without it, quantum key distribution would be a neat physics demo and little more.
A professor at the Université de Montréal since 1979, he wrote the textbook Modern Cryptology (1988) and co-authored the 1993 quantum teleportation paper. He shared the 2018 Wolf Prize and the 2023 Turing Award with Bennett — recognition that arrived roughly when quantum computers started making their work urgent.