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data::entropy::rawsource::randomnumbersinfo(3pm) [debian man page]

Data::Entropy::RawSource::RandomnumbersInfo(3pm)	User Contributed Perl Documentation	  Data::Entropy::RawSource::RandomnumbersInfo(3pm)

NAME

       Data::Entropy::RawSource::RandomnumbersInfo - download entropy from randomnumbers.info

SYNOPSIS

	       use Data::Entropy::RawSource::RandomnumbersInfo;

	       my $rawsrc = Data::Entropy::RawSource::RandomnumbersInfo->new;

	       $c = $rawsrc->getc;
	       # and the rest of the I/O handle interface

DESCRIPTION

       This class provides an I/O handle connected to a stream of random octets being generated by a quantum random number generator (from the
       company id Quantique) connected to the randomnumbers.info server at the University of Geneva.  This is a strong source of random bits, but
       is not suitable for security applications because the bits are passed over the Internet unencrypted.  The handle implements a substantial
       subset of the interface described in IO::Handle.

       For use as a general entropy source, it is recommended to wrap an object of this class using "Data::Entropy::Source", which provides
       methods to extract entropy in more convenient forms than mere octets.

       The bits generated at randomnumbers.info are, theoretically and as far as anyone can tell, totally unbiased and uncorrelated.  However,
       they are sent over the Internet in the clear, and so are subject to interception and alteration by an adversary.  This is therefore
       generally unsuitable for security applications.	Applications requiring secret entropy should generate it locally (see
       Data::Entropy::RawSource::Local).  Applications requiring a large amount of apparently-random data, but not true entropy, might prefer to
       fake it cryptographically (see Data::Entropy::RawSource::CryptCounter).

CONSTRUCTOR

       Data::Entropy::RawSource::RandomnumbersInfo->new
	   Creates and returns a handle object referring to a stream of random octets generated by randomnumbers.info.

METHODS

       A subset of the interfaces described in IO::Handle and IO::Seekable are provided:

       $rawsrc->read(BUFFER, LENGTH[, OFFSET])
       $rawsrc->getc
       $rawsrc->ungetc(ORD)
       $rawsrc->eof
	   Buffered reading from the source, as in IO::Handle.

       $rawsrc->sysread(BUFFER, LENGTH[, OFFSET])
	   Unbuffered reading from the source, as in IO::Handle.

       $rawsrc->close
	   Does nothing.

       $rawsrc->opened
	   Retruns true to indicate that the source is available for I/O.

       $rawsrc->clearerr
       $rawsrc->error
	   Error handling, as in IO::Handle.

       The buffered ("read" et al) and unbuffered ("sysread" et al) sets of methods are interchangeable, because no such distinction is made by
       this class.

       Methods to write to the file are unimplemented because the stream is fundamentally read-only.  Methods to seek are unimplemented because
       the stream is non-rewindable; "ungetc" works, however.

SEE ALSO

       Data::Entropy::RawSource::CryptCounter, Data::Entropy::RawSource::Local, Data::Entropy::RawSource::RandomOrg, Data::Entropy::Source,
       <http://www.randomnumbers.info>

AUTHOR

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

COPYRIGHT

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

LICENSE

       This module is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

perl v5.12.3							    2011-05-09			  Data::Entropy::RawSource::RandomnumbersInfo(3pm)

Check Out this Related Man Page

Data::Entropy(3pm)					User Contributed Perl Documentation					Data::Entropy(3pm)

NAME

       Data::Entropy - entropy (randomness) management

SYNOPSIS

	       use Data::Entropy qw(entropy_source);

	       $i = entropy_source->get_int(12345);

	       use Data::Entropy qw(with_entropy_source);

	       with_entropy_source $source, sub {
		       @a = shuffle(@a);
	       };

DESCRIPTION

       This module maintains a concept of a current selection of entropy source.  Algorithms that require entropy, such as those in
       Data::Entropy::Algorithms, can use the source nominated by this module, avoiding the need for entropy source objects to be explicitly
       passed around.  This is convenient because usually one entropy source will be used for an entire program run and so an explicit entropy
       source parameter would rarely vary.  There is also a default entropy source, avoiding the need to explicitly configure a source at all.

       If nothing is done to set a source then it defaults to the use of Rijndael (AES) in counter mode (see
       Data::Entropy::RawSource::CryptCounter and Crypt::Rijndael), keyed using Perl's built-in "rand" function.  This gives a data stream that
       looks like concentrated entropy, but really only has at most the entropy of the "rand" seed.  Within a single run it is cryptographically
       difficult to detect the correlation between parts of the pseudo-entropy stream.	If more true entropy is required then it is necessary to
       configure a different entropy source.

FUNCTIONS

       entropy_source
	   Returns the current entropy source, a "Data::Entropy::Source" object.  This will be the source passed to the innermost call to
	   "with_entropy_source", if any, or otherwise the default entropy source.

       with_entropy_source SOURCE, CLOSURE
	   The SOURCE is selected, so that it will be returned by "entropy_source", and CLOSURE is called (with no arguments).	The SOURCE is
	   selected only during the dynamic scope of the call; after CLOSURE finishes, by whatever means, the previously selected entropy source
	   is restored.

	   SOURCE is normally a "Data::Entropy::Source" object.  Alternatively, it may be "undef" to cause use of the default entropy source.  It
	   may also be a reference to a function of no arguments, which will be called to generate the actual source only if required.	This
	   avoids unnecessarily initialising the source object if it is uncertain whether any entropy will be required.  The source-generating
	   closure may return a normal source or "undef", but not another function reference.

SEE ALSO

       Data::Entropy::Algorithms, Data::Entropy::Source

AUTHOR

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

COPYRIGHT

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

LICENSE

       This module is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

perl v5.12.3							    2011-05-09							Data::Entropy(3pm)
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