RAND_load_file, RAND_write_file, RAND_file_name - PRNG seed file
#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);
RAND_load_file()
reads a number of bytes from file filename and
adds them to the PRNG. If max_bytes is non-negative,
up to max_bytes are read;
if max_bytes is -1, the complete file is read.
Do not load the same file multiple times unless its contents have
been updated by RAND_write_file()
between reads.
Also, note that filename should be adequately protected so that an
attacker cannot replace or examine the contents.
If filename 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.
RAND_write_file()
writes a number of random bytes (currently 128) to
file filename which can be used to initialize the PRNG by calling
RAND_load_file()
in a later session.
RAND_file_name()
generates a default path for the random seed
file. buf points to a buffer of size num in which to store the
filename.
On all systems, if the environment variable RANDFILE is set, its
value will be used as the seed file name.
Otherwise, the file is called .rnd
, found in platform dependent locations:
%HOME%, %USERPROFILE%, %SYSTEMROOT%, C:\
SYS$LOGIN:
$HOME
If $HOME
(on non-Windows and non-VMS system) is not set either, or
num is too small for the path name, an error occurs.
RAND_load_file()
returns the number of bytes read or -1 on error.
RAND_write_file()
returns the number of bytes written, or -1 if the
bytes written were generated without appropriate seeding.
RAND_file_name()
returns a pointer to buf on success, and NULL on
error.
RAND_add(3), RAND_bytes(3), RAND(7)
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.