NAME

       RAND_egd, RAND_egd_bytes, RAND_query_egd_bytes - query entropy gathering daemon

SYNOPSIS

        #include <openssl/rand.h>

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

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

DESCRIPTION

       On older platforms without a good source of randomness such as "/dev/urandom", it is
       possible to query an Entropy Gathering Daemon (EGD) over a local socket to obtain
       randomness and seed the OpenSSL RNG.  The protocol used is defined by the EGDs available
       at <http://egd.sourceforge.net/> or <http://prngd.sourceforge.net>.

       RAND_egd_bytes() requests num bytes of randomness from an EGD at the specified socket
       path, and passes the data it receives into RAND_add().  RAND_egd() is equivalent to
       RAND_egd_bytes() with num set to 255.

       RAND_query_egd_bytes() requests num bytes of randomness from an EGD at the specified
       socket path, where num must be less than 256.  If buf is NULL, it is equivalent to
       RAND_egd_bytes().  If buf is not NULL, then the data is copied to the buffer and
       RAND_add() is not called.

       OpenSSL can be configured at build time to try to use the EGD for seeding automatically.

RETURN VALUES

       RAND_egd() and RAND_egd_bytes() return the number of bytes read from the daemon on
       success, or -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, or -1
       if the connection failed.

SEE ALSO

       RAND_add(3), RAND_bytes(3), RAND(7)

COPYRIGHT

       Copyright 2000-2018 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the OpenSSL license (the "License").  You may not use this file except in
       compliance with the License.  You can obtain a copy in the file LICENSE in the source
       distribution or at <https://www.openssl.org/source/license.html>.