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Always turn off hyphenation; it makes .\" way too many mistakes in technical documents. .if n .ad l .nh .SH "NAME" RAND_egd, RAND_egd_bytes, RAND_query_egd_bytes \- query entropy gathering daemon .SH "SYNOPSIS" .IX Header "SYNOPSIS" .Vb 1 \& #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); .Ve .SH "DESCRIPTION" .IX Header "DESCRIPTION" On older platforms without a good source of randomness such as \f(CW\*(C`/dev/urandom\*(C'\fR, it is possible to query an Entropy Gathering Daemon (\s-1EGD\s0) over a local socket to obtain randomness and seed the OpenSSL \s-1RNG.\s0 The protocol used is defined by the EGDs available at <http://egd.sourceforge.net/> or <http://prngd.sourceforge.net>. .PP \&\fBRAND_egd_bytes()\fR requests \fBnum\fR bytes of randomness from an \s-1EGD\s0 at the specified socket \fBpath\fR, and passes the data it receives into \fBRAND_add()\fR. \&\fBRAND_egd()\fR is equivalent to \fBRAND_egd_bytes()\fR with \fBnum\fR set to 255. .PP \&\fBRAND_query_egd_bytes()\fR requests \fBnum\fR bytes of randomness from an \s-1EGD\s0 at the specified socket \fBpath\fR, where \fBnum\fR must be less than 256. If \fBbuf\fR is \fB\s-1NULL\s0\fR, it is equivalent to \fBRAND_egd_bytes()\fR. If \fBbuf\fR is not \fB\s-1NULL\s0\fR, then the data is copied to the buffer and \&\fBRAND_add()\fR is not called. .PP OpenSSL can be configured at build time to try to use the \s-1EGD\s0 for seeding automatically. .SH "RETURN VALUES" .IX Header "RETURN VALUES" \&\fBRAND_egd()\fR and \fBRAND_egd_bytes()\fR 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 \s-1PRNG.\s0 .PP \&\fBRAND_query_egd_bytes()\fR returns the number of bytes read from the daemon on success, or \-1 if the connection failed. .SH "SEE ALSO" .IX Header "SEE ALSO" \&\fBRAND_add\fR\|(3), \&\fBRAND_bytes\fR\|(3), \&\s-1\fBRAND\s0\fR\|(7) .SH "COPYRIGHT" .IX Header "COPYRIGHT" Copyright 2000\-2018 The OpenSSL Project Authors. All Rights Reserved. .PP Licensed under the OpenSSL license (the \*(L"License\*(R"). You may not use this file except in compliance with the License. You can obtain a copy in the file \s-1LICENSE\s0 in the source distribution or at <https://www.openssl.org/source/license.html>.