Koha/AuthUtils.pm

   1 package Koha::AuthUtils;
   2
   3 # Copyright 2013 Catalyst IT
   4 #
   5 # This file is part of Koha.
   6 #
   7 # Koha is free software; you can redistribute it and/or modify it
   8 # under the terms of the GNU General Public License as published by
   9 # the Free Software Foundation; either version 3 of the License, or
  10 # (at your option) any later version.
  11 #
  12 # Koha is distributed in the hope that it will be useful, but
  13 # WITHOUT ANY WARRANTY; without even the implied warranty of
  14 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  15 # GNU General Public License for more details.
  16 #
  17 # You should have received a copy of the GNU General Public License
  18 # along with Koha; if not, see <http://www.gnu.org/licenses>.
  19
  20 use Modern::Perl;
  21 use Crypt::Eksblowfish::Bcrypt qw(bcrypt en_base64);
  22 use Fcntl qw/O_RDONLY/; # O_RDONLY is used in generate_salt
  23
  24 use base 'Exporter';
  25
  26 our $VERSION = '1.01';
  27 our @EXPORT_OK   = qw(hash_password);
  28
  29 =head1 NAME
  30
  31 Koha::AuthUtils - utility routines for authentication
  32
  33 =head1 SYNOPSIS
  34
  35     use Koha::AuthUtils qw/hash_password/;
  36     my $hash = hash_password($password);
  37
  38 =head1 DESCRIPTION
  39
  40 This module provides utility functions related to managing
  41 user passwords.
  42
  43 =head1 FUNCTIONS
  44
  45 =head2 hash_password
  46
  47     my $hash = Koha::AuthUtils::hash_password($password, $settings);
  48
  49 =cut
  50
  51 # Using Bcrypt method for hashing. This can be changed to something else in future, if needed.
  52 sub hash_password {
  53     my $password = shift;
  54
  55     # Generate a salt if one is not passed
  56     my $settings = shift;
  57     unless( defined $settings ){ # if there are no settings, we need to create a salt and append settings
  58     # Set the cost to 8 and append a NULL
  59         $settings = '$2a$08$'.en_base64(generate_salt('weak', 16));
  60     }
  61     # Encrypt it
  62     return bcrypt($password, $settings);
  63 }
  64
  65 =head2 generate_salt
  66
  67     my $salt = Koha::Auth::generate_salt($strength, $length);
  68
  69 =over
  70
  71 =item strength
  72
  73 For general password salting a C<$strength> of C<weak> is recommend,
  74 For generating a server-salt a C<$strength> of C<strong> is recommended
  75
  76 'strong' uses /dev/random which may block until sufficient entropy is acheived.
  77 'weak' uses /dev/urandom and is non-blocking.
  78
  79 =item length
  80
  81 C<$length> is a positive integer which specifies the desired length of the returned string
  82
  83 =back
  84
  85 =cut
  86
  87
  88 # the implementation of generate_salt is loosely based on Crypt::Random::Provider::File
  89 sub generate_salt {
  90     # strength is 'strong' or 'weak'
  91     # length is number of bytes to read, positive integer
  92     my ($strength, $length) = @_;
  93
  94     my $source;
  95
  96     if( $length < 1 ){
  97         die "non-positive strength of '$strength' passed to Koha::AuthUtils::generate_salt\n";
  98     }
  99
 100     if( $strength eq "strong" ){
 101         $source = '/dev/random'; # blocking
 102     } else {
 103         unless( $strength eq 'weak' ){
 104             warn "unsuppored strength of '$strength' passed to Koha::AuthUtils::generate_salt, defaulting to 'weak'\n";
 105         }
 106         $source = '/dev/urandom'; # non-blocking
 107     }
 108
 109     sysopen SOURCE, $source, O_RDONLY
 110         or die "failed to open source '$source' in Koha::AuthUtils::generate_salt\n";
 111
 112     # $bytes is the bytes just read
 113     # $string is the concatenation of all the bytes read so far
 114     my( $bytes, $string ) = ("", "");
 115
 116     # keep reading until we have $length bytes in $strength
 117     while( length($string) < $length ){
 118         # return the number of bytes read, 0 (EOF), or -1 (ERROR)
 119         my $return = sysread SOURCE, $bytes, $length - length($string);
 120
 121         # if no bytes were read, keep reading (if using /dev/random it is possible there was insufficient entropy so this may block)
 122         next unless $return;
 123         if( $return == -1 ){
 124             die "error while reading from $source in Koha::AuthUtils::generate_salt\n";
 125         }
 126
 127         $string .= $bytes;
 128     }
 129
 130     close SOURCE;
 131     return $string;
 132 }
 133 1;
 134
 135 __END__
 136
 137 =head1 SEE ALSO
 138
 139 Crypt::Eksblowfish::Bcrypt(3)
 140
 141 =cut