1Data::Entropy::RawSourcUes:e:rLoCcoanlt(r3i)buted Perl DDoactuam:e:nEtnattrioopny::RawSource::Local(3)
2
3
4

NAME

6       Data::Entropy::RawSource::Local - read randomness from local device
7

SYNOPSIS

9               use Data::Entropy::RawSource::Local;
10
11               my $rawsrc = Data::Entropy::RawSource::Local->new;
12
13               $rawsrc->sysread($c, 1);
14               # and the rest of the I/O handle interface
15

DESCRIPTION

17       This class provides a constructor to open an I/O handle connected to a
18       local source of random octets.  This may be a strong entropy source,
19       depending on the OS, but not every OS has such a facility at all.
20
21       There are no actual objects blessed into this class.  Only the
22       constructor belongs to this class; it returns "IO::File" objects.  For
23       use as a general entropy source, it is recommended to wrap the handle
24       using "Data::Entropy::Source", which provides methods to extract
25       entropy in more convenient forms than mere octets.
26
27       On systems with a blocking /dev/random, such as Linux, the bits
28       generated can be totally unbiased and uncorrelated.  Such an entropy
29       stream is suitable for all uses, including security applications.
30       However, the rate of entropy generation is limited, so applications
31       requiring a large amount of apparently-random data might prefer to fake
32       it cryptographically (see Data::Entropy::RawSource::CryptCounter).
33
34       On systems where /dev/random does not block, the bits generated are
35       necessarily correlated to some extent, but it should be
36       cryptographically difficult to detect the correlation.  Such an entropy
37       source is not suitable for all applications.  Some other systems lack
38       /dev/random entirely.  If satisfactory entropy cannot be generated
39       locally, consider downloading it from a server (see
40       Data::Entropy::RawSource::RandomOrg and
41       Data::Entropy::RawSource::RandomnumbersInfo).
42

CONSTRUCTOR

44       Data::Entropy::RawSource::Local->new([FILENAME])
45           Opens a file handle referring to the randomness device, or "die"s
46           on error.  The device opened is /dev/random by default, but this
47           may be overridden by giving a FILENAME argument.
48
49           The default device name may in the future be different on different
50           OSes, if their equivalent devices are in different places.
51

METHODS

53       There are no actual objects blessed into this class.  The constuctor
54       returns "IO::File" objects.  See IO::File for the interface.  It is
55       recommended to use unbuffered reads (the "sysread" method) rather than
56       buffered reads (the "getc" method et al), to avoid wasting entropy that
57       could be used by another process.
58

SEE ALSO

60       Data::Entropy::RawSource::CryptCounter,
61       Data::Entropy::RawSource::RandomOrg,
62       Data::Entropy::RawSource::RandomnumbersInfo, Data::Entropy::Source,
63       IO::File
64

AUTHOR

66       Andrew Main (Zefram) <zefram@fysh.org>
67

69       Copyright (C) 2006, 2007, 2009, 2011 Andrew Main (Zefram)
70       <zefram@fysh.org>
71

LICENSE

73       This module is free software; you can redistribute it and/or modify it
74       under the same terms as Perl itself.
75
76
77
78perl v5.32.1                      2021-01-27Data::Entropy::RawSource::Local(3)
Impressum