Harald Niederreiter
Austrian mathematician whose 1986 code-based cryptosystem turned McEliece inside out – and forty years later lives on as Classic McEliece.
Born in Vienna in 1944, Niederreiter was a number theorist first. He wrote the standard reference Finite Fields with Rudolf Lidl (1983), and numerical analysts know him equally well for Niederreiter sequences, low-discrepancy sequences that make quasi-Monte Carlo integration smoother than randomness can.
His cryptosystem rests on the same hard problem as Robert McEliece's from 1978 – decoding a random-looking linear code – but encrypts into the syndrome rather than a codeword. Ciphertexts get shorter, and the security was later shown to be equivalent. The original Reed–Solomon instantiation was broken in 1992; the idea with Goppa codes held. When Classic McEliece went into NIST's post-quantum competition, it was in practice Niederreiter's formulation wearing McEliece's name.