Bcrypt using 2080ti slow

[Claven99]

I have a relatively new PC 9900K/2080ti, running Windows 10, plenty of memory.

Installed latest hashcat and find BCRYPT H/s too slow compared to benchmarks.

GPU at 750 H/s (CPU at 332 H/s)
(command line hashcat64 -a 0 -m 3200 hash.txt found.txt wordlist.txt -O -w3 -D1,2,3)

Sample hash is $2a$10...
Benchmarks I've found suggest figure should be considerably higher for GPU (though many benchmarks don't show $ rounds)

Tried installing CUDA SDK - appears to have no effect.

Searched throughout forum - no answers found.

Comments/suggestions appreciated.

[Chick3nman]

Bcrypt hashes have a configurable cost or round count. The benchmark uses 05 cost, your hash is 10 cost. The cost for bcrypt represents 2^cost rounds of hashing. So 2^10 instead of 2^5, which is a significantly higher and significantly slower hash to generate. This is working as expected.

[Claven99]

Chick3nman, thanks for your reply.

I was curious about the benchmarks not showing the cost/round count.

I also thought it odd that the CPU rate was so close (relatively) to the GPU rate.

While I accept your reply as accurate, if there are any others readers of this thread with a 2080ti with a similar (or materially higher) H/s rate for the above hash type, please reply.

Thanks again

[the_charm]

Hey Claven99. Chick3nman is absolutely right and your speeds are perfectly normal.
~750H/s is just what you get with 10 rounds of bcrypt. bcrypt is notoriously GPU-unfriendly.
That's why you sometimes see people recommending to run it on CPU instead.
As you noted yourself, the CPU rate can be relatively close to the GPU rate. So it's not hard to imagine that on some systems, the CPU(s) can actually outperform the GPU(s).

[Claven99]

the_charm - thanks for your comments.