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author | Jeff Forcier <jeff@bitprophet.org> | 2016-09-21 16:34:01 -0700 |
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committer | Jeff Forcier <jeff@bitprophet.org> | 2016-09-21 16:34:01 -0700 |
commit | 6f4aaa169fa21b1593c7af91b119a2aeab6da10c (patch) | |
tree | 8e00b9f77356e7f32b4db723bf822d1bf6b3ec21 /sites/www | |
parent | efdcfd275f163a8d96253dbf6f036e3804e165db (diff) | |
parent | 8916228ed0b9f3771c4aad05b095bb9f97509e1b (diff) |
Merge branch '1.15' into 1.16
Diffstat (limited to 'sites/www')
-rw-r--r-- | sites/www/installing.rst | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/sites/www/installing.rst b/sites/www/installing.rst index 3e96a50f..f16369ff 100644 --- a/sites/www/installing.rst +++ b/sites/www/installing.rst @@ -66,6 +66,32 @@ Tools on the Mac, or the ``build-essential`` package on Ubuntu or Debian Linux -- basically, anything with ``gcc``, ``make`` and so forth) as well as the Python development libraries, often named ``python-dev`` or similar. +Slow vs fast crypto math +~~~~~~~~~~~~~~~~~~~~~~~~ + +PyCrypto attempts to use the ``gmp`` C math library if it is present on your +system, which enables what it internally calls "fastmath" (``_fastmath.so``). +When those headers are not available, it falls back to "slowmath" +(``_slowmath.py``) which is a pure-Python implementation. + +Real-world tests have shown significant benefits to using the C version of this +code; thus we strongly recommend you install the ``gmp`` development headers +**before** installing Paramiko/PyCrypto. E.g.:: + + $ apt-get install libgmp-dev # or just apt + $ yum install gmp-devel # or dnf + $ brew install gmp + +If you're unsure which version of math you've ended up with, a quick way to +check is to examine whether ``_fastmath.so`` or ``_slowmath.py`` appears in the +output of:: + + from Crypto.PublicKey import RSA + print(RSA._impl._math) + +Windows +~~~~~~~ + For **Windows** users we recommend using :ref:`pypm`, installing a C development environment such as `Cygwin <http://cygwin.com>`_ or obtaining a precompiled Win32 PyCrypto package from `voidspace's Python modules page |