1=pod 2 3=head1 NAME 4 5RAND_egd, RAND_egd_bytes, RAND_query_egd_bytes - query entropy gathering daemon 6 7=head1 SYNOPSIS 8 9 #include <openssl/rand.h> 10 11 int RAND_egd_bytes(const char *path, int num); 12 int RAND_egd(const char *path); 13 14 int RAND_query_egd_bytes(const char *path, unsigned char *buf, int num); 15 16=head1 DESCRIPTION 17 18On older platforms without a good source of randomness such as C</dev/urandom>, 19it is possible to query an Entropy Gathering Daemon (EGD) over a local 20socket to obtain randomness and seed the OpenSSL RNG. 21The protocol used is defined by the EGDs available at 22L<http://egd.sourceforge.net/> or L<http://prngd.sourceforge.net>. 23 24RAND_egd_bytes() requests B<num> bytes of randomness from an EGD at the 25specified socket B<path>, and passes the data it receives into RAND_add(). 26RAND_egd() is equivalent to RAND_egd_bytes() with B<num> set to 255. 27 28RAND_query_egd_bytes() requests B<num> bytes of randomness from an EGD at 29the specified socket B<path>, where B<num> must be less than 256. 30If B<buf> is B<NULL>, it is equivalent to RAND_egd_bytes(). 31If B<buf> is not B<NULL>, then the data is copied to the buffer and 32RAND_add() is not called. 33 34OpenSSL can be configured at build time to try to use the EGD for seeding 35automatically. 36 37=head1 RETURN VALUES 38 39RAND_egd() and RAND_egd_bytes() return the number of bytes read from the 40daemon on success, or -1 if the connection failed or the daemon did not 41return enough data to fully seed the PRNG. 42 43RAND_query_egd_bytes() returns the number of bytes read from the daemon on 44success, or -1 if the connection failed. 45 46=head1 SEE ALSO 47 48L<RAND_add(3)>, 49L<RAND_bytes(3)>, 50L<RAND(7)> 51 52=head1 COPYRIGHT 53 54Copyright 2000-2018 The OpenSSL Project Authors. All Rights Reserved. 55 56Licensed under the Apache License 2.0 (the "License"). You may not use 57this file except in compliance with the License. You can obtain a copy 58in the file LICENSE in the source distribution or at 59L<https://www.openssl.org/source/license.html>. 60 61=cut 62
