Shor has designed a quantum algorithm for factoring large prime numbers. That is quantum computers shall break state of the art cryptographic techniques such as RSA, DSA, and ECDSA.
Once the first quantum computer leaps out of the laboratory – most probably in the second half of 2017, all classical security systems may suffer an unprecedented hazard. Hence, Post-Quantum Cryptography is a new field of research that has emerged to focus on the crypto-analysis of quantum attacks on classical systems.
Post-Quantum Cryptography has risen based on the necessity to develop new protocols, algorithms, and techniques. In 2016, Google has introduced the New Hope algorithm as a component of Chrome Canary in order to immune classical systems against quantum cryptographic attacks.
Crypto-analysts have spent years evaluating potential attacks. So far RSA, DSA, and ECDSA based systems are most likely to suffer such a vulnerability. However, a few other cryptographic techniques may withstand the quantum revolution for a bit longer. Hash-based, Code-based, Multivariate quadratic equations, and secret-key based cryptographic systems are examples of such.