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Use Crypt::URandom to get the random seed #4

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Use Crypt::URandom to get the random seed #4

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11 changes: 5 additions & 6 deletions Makefile.PL
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Original file line number Diff line number Diff line change
Expand Up @@ -3,15 +3,14 @@ use strict;

use ExtUtils::MakeMaker;

my $deps = {};

$deps->{'Crypt::Random::Source::Strong::Win32'} = 0
if $^O =~ /mswin/i;
my %deps = (
'Crypt::URandom' => '0.37',
);

my %args = (
NAME => 'Session::Token',
VERSION_FROM => 'lib/Session/Token.pm',
PREREQ_PM => $deps,
PREREQ_PM => \%deps,
LIBS => [''],
DEFINE => '',
INC => '-I.',
Expand All @@ -20,7 +19,7 @@ my %args = (
dist => {
PREOP => 'pod2text $(VERSION_FROM) > $(DISTVNAME)/README',
},
MIN_PERL_VERSION => '5.8.0',
MIN_PERL_VERSION => '5.6.0',
);


Expand Down
38 changes: 3 additions & 35 deletions lib/Session/Token.pm
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Original file line number Diff line number Diff line change
Expand Up @@ -3,9 +3,9 @@ package Session::Token;
use strict;

use Carp qw/croak/;
use Crypt::URandom qw/urandom/;
use POSIX qw/ceil/;


our $VERSION = '1.503';

require XSLoader;
Expand All @@ -15,14 +15,6 @@ XSLoader::load('Session::Token', $VERSION);
my $default_alphabet = join('', ('0'..'9', 'a'..'z', 'A'..'Z',));
my $default_entropy = 128;

my $is_windows;

if ($^O =~ /mswin/i) {
require Crypt::Random::Source::Strong::Win32;
$is_windows = 1;
}


sub new {
my ($class, @args) = @_;

Expand All @@ -43,26 +35,9 @@ sub new {
}

if (!defined $seed) {
if ($is_windows) {
my $windows_rng_source = Crypt::Random::Source::Strong::Win32->new;
$seed = $windows_rng_source->get(1024);
die "Win32 RNG source didn't provide 1024 bytes" unless length($seed) == 1024;
} else {
my ($fh, $err1, $err2);

open($fh, '<:raw', '/dev/urandom') || ($err1 = $!);
open($fh, '<:raw', '/dev/arandom') || ($err2 = $!)
unless defined $fh;

if (!defined $fh) {
croak "unable to open /dev/urandom ($err1) or /dev/arandom ($err2)";
}

sysread($fh, $seed, 1024) == 1024 || croak "unable to read from random device: $!";
}
$seed = urandom(1024);
}


## Init alphabet

my $alphabet = defined $args{alphabet} ? $args{alphabet} : $default_alphabet;
Expand Down Expand Up @@ -140,7 +115,7 @@ Session::Token - Secure, efficient, simple random session token generation

This module provides a secure, efficient, and simple interface for creating session tokens, password reset codes, temporary passwords, random identifiers, and anything else you can think of.

When a Session::Token object is created, 1024 bytes are read from C</dev/urandom> (Linux, Solaris, most BSDs), C</dev/arandom> (some older BSDs), or L<Crypt::Random::Source::Strong::Win32> (Windows). These bytes are used to seed the L<ISAAC-32|http://www.burtleburtle.net/bob/rand/isaacafa.html> pseudo random number generator.
When a Session::Token object is created, 1024 bytes are read from L<Crypt::URandom>. These bytes are used to seed the L<ISAAC-32|http://www.burtleburtle.net/bob/rand/isaacafa.html> pseudo random number generator.

Once a generator is created, you can repeatedly call the C<get> method on the generator object and it will return a new token each time.

Expand Down Expand Up @@ -420,13 +395,6 @@ Would be cool if it could detect forks and warn or re-seed in the child process

There is currently no way to extract the seed from a Session::Token object. Note when implementing this: The saved seed must either store the current state of the ISAAC round as well as the 1024 byte C<randsl> array or else do some kind of minimum fast forwarding in order to protect against a partially duplicated output-stream bug.

Doesn't work on perl 5.6 and below due to the use of C<:raw> (thanks CPAN testers). It could probably use C<binmode> instead, but meh.

On windows we use L<Crypt::Random::Source::Strong::Win32> which has a big dependency tree. We should instead use a slimmer module like L<Crypt::Random::Seed>.




=head1 SEE ALSO

L<The Session::Token github repo|https://github.com/hoytech/Session-Token>
Expand Down