Be warned: the details of PQ cryptography can be quite complicated. In some cases it relies on classical cryptography, and in other cases it is completely different from mathematics. It would be quite difficult to describe the details in a single blog post. Instead, we give you an intuition of post-quantitative cryptography, instead of providing deep descriptions at the academic level. We skip a lot of details for reasons of brevity. Nevertheless, you settle for a bit of an epic journey, because we have a lot to cover. I skipped a lot of important details to give a brief description of how crypto based on isogenics works. If you`re curious and eager for details, check out one of those cloudflare meetings where Deirdre Connolly talked about isogeny cryptography or chloe Martindale`s lecture during the 2017 PQ Crypto School. And if you want to know more about quantum attacks on this scheme, I highly recommend this work.
If large enough key sizes are used, cryptographic symmetrical key systems such as AES and SNOW 3G are already resistant to attacks from a quantum computer.  In addition, key management systems and protocols that use symmetrical key cryptography instead of public key cryptography like Kerberos and the 3GPP mobile authentication structure are by nature also safe from attacks by a quantum computer. Given its wide global reach, some researchers recommend extensive use of Kerberos-type symmetrical key management as an effective way to obtain post-quantenkryptography today.  The Transport Layer Security (TLS) protocol is one of the most widely used security protocols today to protect information exchanged between web customers and servers around the world. While TLS is safe from today`s conventional computers, asymmetric cryptography in TLS is unfortunately vulnerable to future attacks from quantum computers. The PQ range of OpenSSL is here: github.com/open-quantum-safe/openssl/tree/OQS-OpenSSL_1_1_1-stable A quantum computer can help solve some of the intractable problems on a conventional computer. In theory, they could effectively solve some basic problems in mathematics. This incredible computing power would be very beneficial, which is why companies are really trying to build quantum computers. At first, Shor`s algorithm was only a theoretical result – quantum computers, which were powerful enough to run it, didn`t exist – but that changes quickly. In March 2018, Google announced a 72-qubit universal quantum computer. Although this is not enough to break, say RSA-2048 (even more is needed), many fundamental problems have already been solved.
These include cryptographic systems such as the Rainbow (Unbalanced Oil and Vinegar) scheme, based on the difficulty of solving multi-vine equation systems. Several attempts to create encryption schemes for secure multivariate equations have failed. However, multivariate signature schemes such as Rainbow could form the basis of a secure quantum digital signature.  There is a patent on the Rainbow Signature Scheme.