diff options
Diffstat (limited to 'docs/topics/auth/passwords.txt')
| -rw-r--r-- | docs/topics/auth/passwords.txt | 14 |
1 files changed, 10 insertions, 4 deletions
diff --git a/docs/topics/auth/passwords.txt b/docs/topics/auth/passwords.txt index 37d6251364..37627ee3b6 100644 --- a/docs/topics/auth/passwords.txt +++ b/docs/topics/auth/passwords.txt @@ -285,15 +285,18 @@ follows: scrypt_ has the following attributes that can be customized: -#. ``work_factor`` controls the number of iterations within the hash. -#. ``block_size`` -#. ``parallelism`` controls how many threads will run in parallel. +#. ``work_factor`` controls the number of iterations within the hash and the + size of memory for computation (*N*). It must be a power of 2. +#. ``block_size`` controls the internal block size (*r*), tuning the algorithm + to memory latency. +#. ``parallelism`` controls how many independent computations may run in + parallel (*p*). #. ``maxmem`` limits the maximum size of memory that can be used during the computation of the hash. Defaults to ``0``, which means the default limitation from the OpenSSL library. We've chosen reasonable defaults, but you may wish to tune it up or down, -depending on your security needs and available processing power. +depending on your security needs and available processing power and memory. .. admonition:: Estimating memory usage @@ -304,6 +307,9 @@ depending on your security needs and available processing power. so you may need to tweak ``maxmem`` when changing the ``work_factor`` or ``block_size`` values. + If the underlying implementation of scrypt_ is fully multithreaded, the + memory requirement is multiplied by the ``parallelism`` value. + .. _password-upgrades: Password upgrading |