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131 .IX Title "RAND_EGD 3"
132 .TH RAND_EGD 3 "2018-11-20" "1.1.1a" "OpenSSL"
133 .\" For nroff, turn off justification. Always turn off hyphenation; it makes
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138 RAND_egd, RAND_egd_bytes, RAND_query_egd_bytes \- query entropy gathering daemon
140 .IX Header "SYNOPSIS"
142 \& #include <openssl/rand.h>
144 \& int RAND_egd_bytes(const char *path, int num);
145 \& int RAND_egd(const char *path);
147 \& int RAND_query_egd_bytes(const char *path, unsigned char *buf, int num);
150 .IX Header "DESCRIPTION"
151 On older platforms without a good source of randomness such as \f(CW\*(C`/dev/urandom\*(C'\fR,
152 it is possible to query an Entropy Gathering Daemon (\s-1EGD\s0) over a local
153 socket to obtain randomness and seed the OpenSSL \s-1RNG.\s0
154 The protocol used is defined by the EGDs available at
155 <http://egd.sourceforge.net/> or <http://prngd.sourceforge.net>.
157 \&\fIRAND_egd_bytes()\fR requests \fBnum\fR bytes of randomness from an \s-1EGD\s0 at the
158 specified socket \fBpath\fR, and passes the data it receives into \fIRAND_add()\fR.
159 \&\fIRAND_egd()\fR is equivalent to \fIRAND_egd_bytes()\fR with \fBnum\fR set to 255.
161 \&\fIRAND_query_egd_bytes()\fR requests \fBnum\fR bytes of randomness from an \s-1EGD\s0 at
162 the specified socket \fBpath\fR, where \fBnum\fR must be less than 256.
163 If \fBbuf\fR is \fB\s-1NULL\s0\fR, it is equivalent to \fIRAND_egd_bytes()\fR.
164 If \fBbuf\fR is not \fB\s-1NULL\s0\fR, then the data is copied to the buffer and
165 \&\fIRAND_add()\fR is not called.
167 OpenSSL can be configured at build time to try to use the \s-1EGD\s0 for seeding
170 .IX Header "RETURN VALUES"
171 \&\fIRAND_egd()\fR and \fIRAND_egd_bytes()\fR return the number of bytes read from the
172 daemon on success, or \-1 if the connection failed or the daemon did not
173 return enough data to fully seed the \s-1PRNG.\s0
175 \&\fIRAND_query_egd_bytes()\fR returns the number of bytes read from the daemon on
176 success, or \-1 if the connection failed.
178 .IX Header "SEE ALSO"
179 \&\fIRAND_add\fR\|(3),
180 \&\fIRAND_bytes\fR\|(3),
181 \&\s-1\fIRAND\s0\fR\|(7)
183 .IX Header "COPYRIGHT"
184 Copyright 2000\-2018 The OpenSSL Project Authors. All Rights Reserved.
186 Licensed under the OpenSSL license (the \*(L"License\*(R"). You may not use
187 this file except in compliance with the License. You can obtain a copy
188 in the file \s-1LICENSE\s0 in the source distribution or at
189 <https://www.openssl.org/source/license.html>.