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Comment by zer01 | Hacker News Reader

I have a feeling that we're going to wake up one day and there will be a legitimate breakthrough in quantum computing, leading to RSA no longer being a legitimate standard for security.

My question to HN: Have any of you guys attempted to come up with a plan for if/when this happens? Are there any algorithms in suites like OpenSSL that are quantum-resistant? Is SSL/TLS even compatible with a post-quantum world?

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There are not, not in OpenSSL. Viable post-quantum encryption is a hot research area right now. There are a number of approaches that seem promising; some of them, like hash-based, lattice-based, and code-based crypto, are actually relatively old concepts that were pushed aside because RSA is more efficient, but which regain their edge if quantum computers become viable.

https://en.wikipedia.org/wiki/Post-quantum_cryptography

The trick with all of this is that there isn't all that much cryptanalysis work of some of the more promising PQ schemes, so trying to preemptively adopt them just in case quantum computers learn to factor numbers bigger than 15 is likely to do more harm, in the short term, than good.

My plan: don't rely on the secrecy of anything encrypted now with RSA to remain secret in 20 years, and never use it for encrypting data-at-rest. Hell, Schneier already increased his PGP key size to 4096 bits, I don't think it's a stretch to think 2048 could be broken classically by USA-level actors in the not-too-distant future. But since you're not using RSA for data-at-rest, more for transient "messages", hopefully the value of anything intercepted and stored for 20 years will be relatively low.

Here's good talk by djb covering the big picture and some options for alternatives that are thought to be quantum-resistant. https://media.ccc.de/v/32c3-7210-pqchacks

People try to come up with a plan. The problem is the plan is in its very early stage. We have a couple of impractical algorithms.

An EU research project has published a couple of recommendations what you can do if you need postquantum today (none of which you want to use for TLS, because the keys or signatures are too big). NIST plans a standardization process. A draft for a stateful hash-based signature scheme (XMSS) is probably going to be an IETF document soon.

Small bits and pieces. People are working on it, but it's still a long way until you will be able to use your browser to establish a quantum-safe https connection.

The PGCRYPTO project [1] a few months ago published a paper with initial recommendations [2] on which algorithms and parameters should work.

[1] https://pqcrypto.eu.org/ [2] https://pqcrypto.eu.org/docs/initial-recommendations.pdf

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