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 nonnegative, 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 filename. Otherwise, the file is called
".rnd", found in platform dependent locations:
- On Windows (in order of preference)
-
%HOME%, %USERPROFILE%, %SYSTEMROOT%, C:\
- On VMS
-
SYS$LOGIN:
- On all other systems
-
$HOME
If $HOME (on non-Windows and non-VMS system) is not set either, or
num is
too small for the pathname, 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 2000-2020 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the Apache License 2.0 (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>.