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comagoosie | 4 years ago

Yeah it's a bummer that a highwayhash is only cryptographically strong (but not cryptographically secure) as it can be significantly faster (3x).

But BLAKE3 does seem to offer the best compromise when a cryptographically secure hash is required.

discuss

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22c|4 years ago

> a highwayhash is only cryptographically strong (but not cryptographically secure)

Can you let me know what you mean by strong vs. secure? When would you use one vs. the other? I've heard both of these terms used but they seem almost interchangeable[1].

I've also heard things like "this would be suitable for encrypting a password which is stored at rest" vs. "this could be suitable for a short lived one-time key", but I don't know what the correct terminology is there.

[1] https://en.wikipedia.org/wiki/Strong_cryptography

tptacek|4 years ago

It's weird terminology. highwayhash aims to be cryptographically secure for its problem domain. But it's designed by (afaik) non-cryptographers, has weird security claims (they gauge security from statistical tests) and hasn't (afaik) received any formal peer review; it can also be instantiated in sub-secure hash sizes. You shouldn't use it to protect secrets, beyond the kind of incident secrecy you'd ask from something like SipHash.

It would be better if people would be clear about this stuff; you see the same thing from the PCG RNG people, who say that their generator isn't a CSPRNG, but is somehow more secure than other non-CSPRNGs.