# Is the proof-of-work algorithm "Quark" insecure?

I recently found out about Quark here.

Apparently it is a proof-of-work algorithm used by several cryptocurrencies and is based on a single-level hash function, which consists of 9 different levels of encryption by six cryptographic algorithms. It also says that Quark provides a "64-bit" protection against hackers.

Isn't 64-bits of protection considered rather insecure? I'm sure a hacker with sufficient computing power can break 64-bits of security given enough time and money. Or am I missing something?

• 32-bit collision resistance is surely inadequate, but to prove you've done $2^{64}$ work can sometimes exceed the capability of moderately sized high-end computers. Feb 15, 2020 at 7:01

## 1 Answer

Quark's overblown security assurances do not add up. Here is how they do testing and code review (see their Github page):

Testing and code review is the bottleneck for development; we get more pull requests than we can review and test on short notice. Please be patient and help out by testing other people's pull requests, and remember this is a security-critical project where any mistake might cost people lots of money.

Whatever.

Quark uses six hash functions in parallel. In cryptography, more is not always better. And the 64-bit protection is not robust.

Quark is not widely accepted and its official feed listed on Twitter goes to an empty webpage. Quark does not inspire confidence and it looks as if it has been thrown together. Given the very evident disorder of everything Quark, and the rather limited security (64-bit), I would be wary. A further note: Wikipedia is not a source of peer-reviewed information! It is often unreliable!