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RAND_EGD(3)                         OpenSSL                        RAND_EGD(3)
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>;.
1.1.1k                            2021-03-25                       RAND_EGD(3)