In 1994 Peter Shor, at AT&T Bell Labs, presents at STOC a quantum algorithm factoring large integers in polynomial time (O((log N)³)), directly threatening RSA and all public-key cryptography based on factorization hardness. Using the quantum Fourier transform to find the period of a modular function, the result turns quantum computing from theoretical curiosity into strategic priority, driving NIST's post-quantum cryptography standardization from 2016.