crypt::openssl::random(3pm) [debian man page]

Random(3pm)						User Contributed Perl Documentation					       Random(3pm)

NAME

       Crypt::OpenSSL::RSA - RSA encoding and decoding, using the openSSL libraries

       Crypt::OpenSSL::Random - Routines for accessing the OpenSSL pseudo-random number generator

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);

DESCRIPTION

       Crypt::OpenSSL::Random provides the ability to seed and query the OpenSSL library's pseudo-random number generator

   EXPORT
       None by default.

Static Methods
       random_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.

       random_pseudo_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.

       random_seed
	   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!

       random_egd
	   This function seeds the PRNG with data from the specified entropy gathering daemon.	Returns the number of bytes read from the daemon
	   on succes, or -1 if not enough bytes were read, or if the connection to the daemon failed.

       random_status
	   This function returns true if the PRNG has sufficient seeding.

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
       random_egd, in one place.

AUTHOR

       Ian Robertson, iroberts@cpan.com

SEE ALSO

       perl(1), rand(3), RAND_add(3), RAND_egd(3), RAND_bytes(3).

POD ERRORS

       Hey! The above document had some coding errors, which are explained below:

       Around line 62:
	   '=item' outside of any '=over'

       Around line 93:
	   You forgot a '=back' before '=head1'

perl v5.14.2							    2007-05-20							       Random(3pm)

RAND_egd(3)							      OpenSSL							       RAND_egd(3)

NAME

       RAND_egd - query entropy gathering daemon

SYNOPSIS

	#include <openssl/rand.h>

	int RAND_egd(const char *path);
	int RAND_egd_bytes(const char *path, int bytes);

	int RAND_query_egd_bytes(const char *path, unsigned char *buf, int bytes);

DESCRIPTION

       RAND_egd() queries the entropy gathering daemon EGD on socket path.  It queries 255 bytes and uses RAND_add(3) to seed the OpenSSL built-in
       PRNG. RAND_egd(path) is a wrapper for RAND_egd_bytes(path, 255);

       RAND_egd_bytes() queries the entropy gathering daemon EGD on socket path.  It queries bytes bytes and uses RAND_add(3) to seed the OpenSSL
       built-in PRNG.  This function is more flexible than RAND_egd().	When only one secret key must be generated, it is not necessary to request
       the full amount 255 bytes from the EGD socket. This can be advantageous, since the amount of entropy that can be retrieved from EGD over
       time is limited.

       RAND_query_egd_bytes() performs the actual query of the EGD daemon on socket path. If buf is given, bytes bytes are queried and written
       into buf. If buf is NULL, bytes bytes are queried and used to seed the OpenSSL built-in PRNG using RAND_add(3).

NOTES

       On systems without /dev/*random devices providing entropy from the kernel, the EGD entropy gathering daemon can be used to collect entropy.
       It provides a socket interface through which entropy can be gathered in chunks up to 255 bytes. Several chunks can be queried during one
       connection.

       EGD is available from http://www.lothar.com/tech/crypto/ ("perl Makefile.PL; make; make install" to install). It is run as egd path, where
       path is an absolute path designating a socket. When RAND_egd() is called with that path as an argument, it tries to read random bytes that
       EGD has collected. The read is performed in non-blocking mode.

       Alternatively, the EGD-interface compatible daemon PRNGD can be used. It is available from http://www.aet.tu-cottbus.de/perso-
       nen/jaenicke/postfix_tls/prngd.html .  PRNGD does employ an internal PRNG itself and can therefore never run out of entropy.

       OpenSSL automatically queries EGD when entropy is requested via RAND_bytes() or the status is checked via RAND_status() for the first time,
       if the socket is located at /var/run/egd-pool, /dev/egd-pool or /etc/egd-pool.

RETURN VALUE

       RAND_egd() and RAND_egd_bytes() return the number of bytes read from the daemon on success, and -1 if the connection failed or the daemon
       did not return enough data to fully seed the PRNG.

       RAND_query_egd_bytes() returns the number of bytes read from the daemon on success, and -1 if the connection failed. The PRNG state is not
       considered.

SEE ALSO

       rand(3), RAND_add(3), RAND_cleanup(3)

HISTORY

       RAND_egd() is available since OpenSSL 0.9.5.

       RAND_egd_bytes() is available since OpenSSL 0.9.6.

       RAND_query_egd_bytes() is available since OpenSSL 0.9.7.

       The automatic query of /var/run/egd-pool et al was added in OpenSSL 0.9.7.

0.9.7d								    2003-11-20							       RAND_egd(3)