3 ms·

It depends on the work factor. On my dev server (a pretty old machine), with a work factor of 7, it's about 300 time slower than md5 (about 10ms per bcrypt has

by chops 15y ago

It depends on the work factor. On my dev server (a pretty old machine), with a work factor of 7, it's about 300 time slower than md5 (about 10ms per bcrypt hash). That's still plenty fast, and much more secure. Bump it to a work factor of 9, and I'm looking at about 1000 times slower (or getting close to 40 ms per hash). Part of its beauty is you can adjust the work factor to match your hardware speed requirements. If you really want ultra-secure, a work factor is 13 is getting pretty slow (about half a second per hash on my crappy machine), and yeah, that might justify an authentication server. (note: my tests were not exhaustive)

cookingrobot 15y ago
Could you design a system where the hard work happens on the client side? For ex, the server sends the client a secret encrypted with the bcrypt hash.. and then the client machine spends a couple seconds working on it and sends back the response. It might allow for a huge work factor without impacting the server.
- mynegation 15y ago
  No, you couldn't. Nothing prevents malicious client from "letting itself in", no matter whether password was correct or not.
pixeloution 15y ago
bcrypt at 10ms only being 300 times slower would indicate you can only try 30,000 MD5 hashes per second -- which is incorrect. Using a GPU based cracker on a current generation top-end video card you can calculate over 300 million per second. Bcrypt at 10ms is 3 million times slower, not 300 times.
- falcolas 15y ago
  Your comparison is flawed - you're comparing GPU evaluation times for MD5 against CPU evaluation of bcrypt.
  - pixeloution 15y ago
    There is no such thing as a GPU based bcrypt hasher because it woudln't be - from my understanding - any faster then a CPU based one. Not all calculations are able to be sped up through the use of a GPU. So I'm comparing the fastest you can do bcrypt hashes (100 a sec at that work factor) vs the fastest you can do MD5 hashes (250 million per second)

by chops 15y ago

cookingrobot 15y ago

Could you design a system where the hard work happens on the client side? For ex, the server sends the client a secret encrypted with the bcrypt hash.. and then the client machine spends a couple seconds working on it and sends back the response. It might allow for a huge work factor without impacting the server.

mynegation 15y ago
No, you couldn't. Nothing prevents malicious client from "letting itself in", no matter whether password was correct or not.

pixeloution 15y ago

bcrypt at 10ms only being 300 times slower would indicate you can only try 30,000 MD5 hashes per second -- which is incorrect. Using a GPU based cracker on a current generation top-end video card you can calculate over 300 million per second. Bcrypt at 10ms is 3 million times slower, not 300 times.

falcolas 15y ago
Your comparison is flawed - you're comparing GPU evaluation times for MD5 against CPU evaluation of bcrypt.
- pixeloution 15y ago
  There is no such thing as a GPU based bcrypt hasher because it woudln't be - from my understanding - any faster then a CPU based one. Not all calculations are able to be sped up through the use of a GPU. So I'm comparing the fastest you can do bcrypt hashes (100 a sec at that work factor) vs the fastest you can do MD5 hashes (250 million per second)