warning: GMP or MPIR library not found; Not building Crypto.PublicKey._fastmath.

[cas...@walboomers.nl]

Hello,

I'm trying to install the yowsup2-2.4.2.tar from pypi, but my system gives
warnings and errors:

warning: GMP or MPIR library not found; Not building
Crypto.PublicKey._fastmath.

more in detail:

running build_ext
building 'Crypto.Random.OSRNG.winrandom' extension
warning: GMP or MPIR library not found; Not building
Crypto.PublicKey._fastmath.
error: [WinError 2] Het systeem kan het opgegeven bestand niet vinden
(dutch for: system can't find a named file)

----------------------------------------
Command "c:\users\ptn\appdata\local\programs\python\python35-32\python.exe
-c "import setuptools,
tokenize;__file__='C:\\Users\\ptn\\AppData\\Local\\Temp\\pip-build-hwbc57ud\\pycrypto\\setup.py';exec(compile(getattr(tokenize,
'open', open)(__file__).read().replace('\r\n', '\n'), __file__, 'exec'))"
install --record
C:\Users\ptn\AppData\Local\Temp\pip-_383sc3p-record\install-record.txt
--single-version-externally-managed --compile" failed with error code 1 in
C:\Users\ptn\AppData\Local\Temp\pip-build-hwbc57ud\pycrypto

I'm using windows-10-X64 and the latest version: python-3.5.0.

How to fix this problem? Or should I run another (lower) version of python?

Please help.

Kind regards,
Caspar

[Paul Rubin]

cas...@walboomers.nl writes:
> warning: GMP or MPIR library not found; Not building Crypto.PublicKey._fastmath.

> How to fix this problem? Or should I run another (lower) version of python?

See if the program works anyway without _fastmath. It would use the
built-in Python arithmetic which is slower but usable unless you have
high performance requirements. According to my benchmarks (a long time
ago on a 32-bit x86) GMP was about 4x faster than Python's bigints. But
your program isn't likely to spend that much of its time doing bignum
math.