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package Crypt::OpenSSL::Random;
use strict;
use vars qw($VERSION @ISA @EXPORT @EXPORT_OK);
use XSLoader;
require Exporter;
@ISA = qw(Exporter);
@EXPORT_OK = qw( random_bytes random_pseudo_bytes random_seed
random_egd random_status );
$VERSION = '0.17';
XSLoader::load( __PACKAGE__, $VERSION );
1;
__END__
=head1 NAME
Crypt::OpenSSL::Random - OpenSSL/LibreSSL pseudo-random number generator access
=head1 SYNOPSIS
use Crypt::OpenSSL::Random;
Crypt::OpenSSL::Random::random_seed($good_random_data);
Crypt::OpenSSL::Random::random_egd("/tmp/entropy");
Crypt::OpenSSL::Random::random_status() or
die "Unable to sufficiently seed the random number generator".
my $ten_good_random_bytes = Crypt::OpenSSL::Random::random_bytes(10);
my $ten_ok_random_bytes = Crypt::OpenSSL::Random::random_pseudo_bytes(10);
=head1 DESCRIPTION
C<Crypt::OpenSSL::Random> provides the ability to seed and query the
B<OpenSSL> and B<LibreSSL> library's pseudo-random number generators.
Note: On B<LibreSSL> C<random_egd()> is not defined.
=head2 EXPORT
None by default.
=head1 Static Methods
=over
=item random_bytes (IV num_bytes)
This function, returns a specified number of cryptographically strong
pseudo-random bytes from the PRNG. If the PRNG has not been seeded
with enough randomness to ensure an unpredictable byte sequence, then
a false value is returned.
=item random_pseudo_bytes (IV num_bytes)
This function, is similar to C<random_bytes>, but the resulting
sequence of bytes are not necessarily unpredictable. They can be used
for non-cryptographic purposes and for certain purposes in
cryptographic protocols, but usually not for key generation etc.
=item random_seed (PV random_bytes_string)
This function seeds the PRNG with a supplied string of bytes. It
returns true if the PRNG has sufficient seeding. Note: calling this
function with non-random bytes is of limited value at best!
=item random_egd (PV egd_string)
This function seeds the PRNG with data from the specified entropy
gathering daemon. Returns the number of bytes read from the daemon on
success, or C<-1> if not enough bytes were read, or if the connection to
the daemon failed.
C<libressl> considers this function insecure, so with libressl or an openssl with
no-egd this function does not exist.
=item random_status ()
This function returns 1 if the PRNG has sufficient seeding. or 0 if not.
=back
=head1 BUGS
Because of the internal workings of OpenSSL's random library, the
pseudo-random number generator (PRNG) accessed by
Crypt::OpenSSL::Random will be different than the one accessed by any
other perl module. Hence, to use a module such as
Crypt::OpenSSL::Random, you will need to seed the PRNG used there from
one used here. This class is still advantageous, however, as it
centralizes other methods, such as C<random_egd>, in one place.
=head1 AUTHOR
Ian Robertson, C<iroberts@cpan.com>
Now maintained by Reini Urban, C<rurban@cpan.org>
=head1 LICENSE
This module is available under the same licences as perl, the Artistic
license and the GPL.
=head1 SEE ALSO
perl(1), rand(3), RAND_add(3), RAND_egd(3), RAND_bytes(3).
=cut
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