RAND_egd(3)
- NetBSD Manual Pages
RAND_egd(3) OpenSSL RAND_egd(3)
NAME
RAND_egd - query entropy gathering daemon
LIBRARY
libcrypto, -lcrypto
SYNOPSIS
#include <openssl/rand.h>
int RAND_egd(const char *path);
int RAND_egd_bytes(const char *path, 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 wrap-
per 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 func-
tion 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.
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 connec-
tion.
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 designat-
ing 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-cot-
tbus.de/personen/jaenicke/postfix_tls/prngd.html . PRNGD
does employ an internal PRNG itself and can therefore
never run out of entropy.
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.
2001-04-12 0.9.6g 1
RAND_egd(3) OpenSSL RAND_egd(3)
SEE ALSO
openssl_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.
2001-04-12 0.9.6g 2
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