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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_load_file, RAND_write_file, RAND_file_name \- PRNG seed file .SH "SYNOPSIS" .IX Header "SYNOPSIS" .Vb 1 \& #include <openssl/rand.h> \& \& int RAND_load_file(const char *filename, long max_bytes); \& \& int RAND_write_file(const char *filename); \& \& const char *RAND_file_name(char *buf, size_t num); .Ve .SH "DESCRIPTION" .IX Header "DESCRIPTION" \&\fBRAND_load_file()\fR reads a number of bytes from file \fBfilename\fR and adds them to the \s-1PRNG.\s0 If \fBmax_bytes\fR is nonnegative, up to \fBmax_bytes\fR are read; if \fBmax_bytes\fR is \-1, the complete file is read. Do not load the same file multiple times unless its contents have been updated by \fBRAND_write_file()\fR between reads. Also, note that \fBfilename\fR should be adequately protected so that an attacker cannot replace or examine the contents. If \fBfilename\fR is not a regular file, then user is considered to be responsible for any side effects, e.g. non-anticipated blocking or capture of controlling terminal. .PP \&\fBRAND_write_file()\fR writes a number of random bytes (currently 128) to file \fBfilename\fR which can be used to initialize the \s-1PRNG\s0 by calling \&\fBRAND_load_file()\fR in a later session. .PP \&\fBRAND_file_name()\fR generates a default path for the random seed file. \fBbuf\fR points to a buffer of size \fBnum\fR in which to store the filename. .PP On all systems, if the environment variable \fB\s-1RANDFILE\s0\fR is set, its value will be used as the seed filename. Otherwise, the file is called \f(CW\*(C`.rnd\*(C'\fR, found in platform dependent locations: .IP "On Windows (in order of preference)" 4 .IX Item "On Windows (in order of preference)" .Vb 1 \& %HOME%, %USERPROFILE%, %SYSTEMROOT%, C:\e .Ve .IP "On \s-1VMS\s0" 4 .IX Item "On VMS" .Vb 1 \& SYS$LOGIN: .Ve .IP "On all other systems" 4 .IX Item "On all other systems" .Vb 1 \& $HOME .Ve .PP If \f(CW$HOME\fR (on non-Windows and non-VMS system) is not set either, or \&\fBnum\fR is too small for the pathname, an error occurs. .SH "RETURN VALUES" .IX Header "RETURN VALUES" \&\fBRAND_load_file()\fR returns the number of bytes read or \-1 on error. .PP \&\fBRAND_write_file()\fR returns the number of bytes written, or \-1 if the bytes written were generated without appropriate seeding. .PP \&\fBRAND_file_name()\fR returns a pointer to \fBbuf\fR on success, and \s-1NULL\s0 on error. .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\-2020 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>.