Update documentation to match the state at 0.9.6 _and_ the recent changes.

 #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);

=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.

RAND_query_egd_bytes() performs the actual query of the EGD daemon on socket

B<path>. If B<buf> is given, B<bytes> bytes are queried and written into

B<buf>. If B<buf> is NULL, B<bytes> bytes are queried and used to seed the

OpenSSL built-in PRNG using L<RAND_add(3)|RAND_add(3)>.

=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>

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.

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.

=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.

RAND_query_egd_bytes() is available since OpenSSL 0.9.7.

=cut