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https://github.com/david-dick/crypt-urandom

Provide non blocking randomness
https://github.com/david-dick/crypt-urandom

getrandom perl perl-module perl5 perl5-module random urandom

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Provide non blocking randomness

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README 

        
NAME



    Crypt::URandom - Provide non blocking randomness



VERSION



    This document describes Crypt::URandom version 0.50



SYNOPSIS



        use Crypt::URandom();

    

        my $random_string_50_bytes_long = Crypt::URandom::urandom(50);



    OR



        use Crypt::URandom qw( urandom );

    

        my $random_string_50_bytes_long = urandom(50);



DESCRIPTION



    This Module is intended to provide an interface to the strongest

    available source of non-blocking randomness on the current platform.

    Platforms currently supported are anything supporting getrandom(2),

    /dev/urandom and versions of Windows greater than or equal to Windows

    2000.



SUBROUTINES/METHODS



    urandom



      This function accepts an integer and returns a string of the same

      size filled with random data. It will throw an exception if the

      requested amount of random data is not returned. The first call will

      initialize the native cryptographic libraries (if necessary) and load

      all the required Perl libraries. This call is a buffered read on non

      Win32 platforms that do not support getrandom(2) or equivalent.



    urandom_ub



      This function accepts an integer and returns a string of the same

      size filled with random data. It will throw an exception if the

      requested amount of random data is not returned. The first call will

      initialize the native cryptographic libraries (if necessary) and load

      all the required Perl libraries. This call is a unbuffered sysread on

      non Win32 platforms that do not support getrandom(2) or equivalent.



    getrandom



      This function accepts an integer and returns a string of the same

      size filled with random data on platforms that implement

      getrandom(2). It will throw an exception if the requested amount of

      random data is not returned. This is NOT portable across all

      operating systems, but is made available if high-speed generation of

      random numbers is required.



DIAGNOSTICS



    No secure alternative for random number generation for Win32 versions

    older than W2K



      The module cannot run on versions of Windows earlier than Windows

      2000 as there is no cryptographic functions provided by the operating

      system.



    Could not import CryptAcquireContext



      The module was unable to load the CryptAcquireContextA function from

      the advapi32 dynamic library. The advapi32 library cannot probably be

      loaded.



    CryptAcquireContext failed



      The module was unable to call the CryptAcquireContextA function from

      the advapi32 dynamic library.



    Could not import CryptGenRandom



      The module was unable to load the CryptGenRandom function from the

      advapi32 dynamic library.



    Could not import SystemFunction036



      The module was unable to load the SystemFunction036 function from the

      advapi32 dynamic library.



    The length argument must be supplied and must be an integer



      The get method must be called with an integer argument to describe

      how many random bytes are required.



    CryptGenRandom failed



      The Windows 2000 CryptGenRandom method call failed to generate the

      required amount of randomness



    RtlGenRand failed



      The post Windows 2000 RtlGenRand method call failed to generate the

      required amount of randomness



    Only read n bytes from path



      The /dev/urandom device did not return the desired amount of random

      bytes



    Failed to read from path



      The /dev/urandom device returned an error when being read from



    Failed to open path



      The /dev/urandom device returned an error when being opened



CONFIGURATION AND ENVIRONMENT



    Crypt::URandom requires no configuration files or environment

    variables.



    If the environment variable CRYPT_URANDOM_BUILD_DEBUG is specified when

    running perl Makefile.PL or make test AND getrandom(2) or it's

    equivalents cannot be detected, extra debug will be shown to show the

    failures to detect these functions.



DEPENDENCIES



      If the platform is Win32, the Win32::API module will be required.

      Otherwise no other modules other than those provided by perl will be

      required



INCOMPATIBILITIES



    None reported.



BUGS AND LIMITATIONS



    To report a bug, or view the current list of bugs, please visit

    https://github.com/david-dick/crypt-urandom/issues



AUTHOR



    David Dick 



ACKNOWLEDGEMENTS



    The Win32::API code for interacting with Microsoft's CryptoAPI

     was copied with

    extreme gratitude from Crypt::Random::Source::Strong::Win32 by Max

    Kanat-Alexander 



LICENSE AND COPYRIGHT



    Copyright (c) 2025, David Dick . All rights reserved.



    This module is free software; you can redistribute it and/or modify it

    under the same terms as Perl itself.



DISCLAIMER OF WARRANTY



    BECAUSE THIS SOFTWARE IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY

    FOR THE SOFTWARE, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT

    WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER

    PARTIES PROVIDE THE SOFTWARE "AS IS" WITHOUT WARRANTY OF ANY KIND,

    EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED

    WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE

    ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE SOFTWARE IS WITH

    YOU. SHOULD THE SOFTWARE PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL

    NECESSARY SERVICING, REPAIR, OR CORRECTION.



    IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING

    WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR

    REDISTRIBUTE THE SOFTWARE AS PERMITTED BY THE ABOVE LICENCE, BE LIABLE

    TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL, OR

    CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE

    SOFTWARE (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING

    RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A

    FAILURE OF THE SOFTWARE TO OPERATE WITH ANY OTHER SOFTWARE), EVEN IF

    SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH

    DAMAGES.