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Comment by flignats | Hacker News Reader

There are several quantum resistant crypto currencies. I.e. IOTA

IOTA isn't even resistant to differential cryptanalysis.

Care to add sources?

A flaw was found in the hash function they rolled themselves which doesn't build confidence there aren't more vulnerabilities to be found:

https://medium.com/@neha/cryptographic-vulnerabilities-in-io...

https://www.forbes.com/sites/amycastor/2017/09/07/mit-and-bu...

To make things even worse than rolling their own hash function, they're claiming the flaw was intentional! This makes them hostile and untrustworthy to the open source community if this is true and further erodes confidence they know what they're doing if this is their attempt at PR spin:

https://hackernoon.com/why-i-find-iota-deeply-alarming-934f1...

> Next, and in my mind most damningly, Sergey Ivancheglo, Iota’s cofounder, claims that the flaws in the Curl hash function were in fact deliberate; that they were inserted as ‘copy protection’, to prevent copycat projects, and to allow the Iota team to compromise those projects if they sprang up.

These points have all been talked over extensively and are not a concern: https://medium.com/@comefrombeyond/cfbs-comments-on-https-ww...

That blog response is completely unconvincing and makes me trust them even less. They have no proof of the extraordinary claim that the flawed hash function was intended (which is bad whether this is true or false) and their network going down for three days is a huge red flag that the protocol cannot be used in a decentralised way. He talks a good game but if you have any technical background you can see he isn't addressing what's being asked and is avoiding valid criticism via hand waving and character attacks.

I disagree with you entirely.

The creator requested an open, live debate to put these claims to rest. They haven't accepted and probably won't.

Can you please explain what makes it quantum resistant?

Not all crypto becomes easy to crack with a quantum computer: https://en.wikipedia.org/wiki/Post-quantum_cryptography

With its use, the scarcity of numbers remain, that is, finding a clash that would allow to forge a transaction stays infeasible, and mining stays hard.

BTW while mining is so important with Bitcoin and Etherium, it's not a necessary part of a cryptocurrency. Mining is an incentive to keep doing blockchain validation. Some currencies exist without it (e.g. NXT).

All crypto becomes easier (well, except for the one time pad). But some algorithms (AES, SHA) only require doubling the number of bits to achieve the same security level, which is rather trivial to do.

To date the only practical replacements for RSA and EC achieve key derivation but not signatures. Without signatures we're not really 'complete' since certificates are hard to do with only key derivation.

Post-quantum cryptograph research is a very active area right now. If these researchers do not find a practical signature algorithm, PKI as we know it will change very significantly.

Ironically, blockchains might elevate in importance as a result, since the evolving blockchain is a useful construct for quantum resistance. It has cryptographic agility built in.

"IOTA uses hash-based signatures (https://www.imperialviolet.org/2013/07/18/hashsig.html) instead of elliptic curve cryptography (ECC). Not only is hash-based signatures a lot faster than ECC, but it also greatly simplifies the overall protocol (signing and verification). What actually makes IOTA quantum-secure is the fact that we use Winternitz signatures. IOTA's ternary hash function is called Curl."

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