Re: Re: [RFC][DISCUSSION] Argon2 Password Hash

On 2016-08-06 17:47, Charles R. Portwood II wrote:

Absolutely. What are your thoughts on the following cost factors? time_cost = 3 memory_cost = 12 threads = 1 The reference library provides a CLI program where these values are listed. A memory_cost factor of 12 would be 4 MiB.

Looks like there's already some ambiguity in the parameters. As I understand it, m_cost is the memory size in kilobytes. Thus, m_cost = 4096 would be 4 MiB. The source file you referenced [1] has actually LOG_M_COST_DEF, where m_cost = 1 << LOG_M_COST_DEF. Testing with argon2_cffi [2] (Python) shows that your parameters (with m_cost = 4096 = 4 MiB) take 57 ms per hash on my laptop and 14 ms on my VPS, compared to bcrypt cost 10 taking 88 ms. Personally, I would be satisfied with even smaller parameters, maybe something like memory_cost 512, time_cost 2, threads 2. Disclaimer: I'm not familiar with Argon2, I only looked shortly at the source files and the Python library [2]. However, care should be taken to use the correct definition for m_cost. [1] https://github.com/P-H-C/phc-winner-argon2/blob/master/src/run.c#L27 [2] http://argon2-cffi.readthedocs.io/en/stable/parameters.html -- Lauri Kenttä