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Update documentation to match the state of OpenSSL 0.9.6.

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Lutz Jänicke 2001-02-08 10:36:37 +00:00
parent 38b3a46ffa
commit 813c7c415b
1 changed files with 31 additions and 5 deletions
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36
doc/crypto/RAND_egd.pod
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@ -9,10 +9,31 @@ RAND_egd - query entropy gathering daemon
#include <openssl/rand.h>
int RAND_egd(const char *path);
int RAND_egd_bytes(const char *path, int bytes);
=head1 DESCRIPTION
RAND_egd() queries the entropy gathering daemon EGD on socket B<path>.
It queries 255 bytes and uses L<RAND_add(3)|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 B<path>.
It queries B<bytes> bytes and uses L<RAND_add(3)|RAND_add(3)> to seed the
OpenSSL built-in PRNG.
=head1 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.
While RAND_egd() is longer available (see HISTORY section), the
RAND_egd_bytes() function is more flexible. When only one secret key must
be generated, it is not needed 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.
EGD is available from http://www.lothar.com/tech/crypto/ (C<perl
Makefile.PL; make; make install> to install). It is run as B<egd>
@ -21,22 +42,27 @@ 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-compatible daemon PRNGD can be used. It is
Alternatively, the EGD-interface compatible daemon PRNGD can be used. It is
available from
http://www.aet.tu-cottbus.de/personen/jaenicke/postfix_tls/prngd.html .
PRNGD does employ an internal PRNG itself and can therefore never run
out of entropy.
=head1 RETURN VALUE
RAND_egd() returns 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_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.
=head1 SEE ALSO
L<rand(3)|rand(3)>, L<RAND_add(3)|RAND_add(3)>, L<RAND_cleanup(3)|RAND_cleanup(3)>
L<rand(3)|rand(3)>, L<RAND_add(3)|RAND_add(3)>,
L<RAND_cleanup(3)|RAND_cleanup(3)>
=head1 HISTORY
RAND_egd() is available since OpenSSL 0.9.5.
RAND_egd_bytes() is available since OpenSSL 0.9.6.
=cut