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Title "RAND_LOAD_FILE 3"
RAND_LOAD_FILE 3 "2022-11-01" "1.1.1s" "OpenSSL"
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"NAME"
RAND_load_file, RAND_write_file, RAND_file_name - PRNG seed file
"SYNOPSIS"
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
"DESCRIPTION"
Header "DESCRIPTION" \fBRAND_load_file() reads a number of bytes from file filename and adds them to the \s-1PRNG.\s0 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.

\fBRAND_write_file() writes a number of random bytes (currently 128) to file filename which can be used to initialize the \s-1PRNG\s0 by calling \fBRAND_load_file() in a later session.

\fBRAND_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 \s-1RANDFILE\s0 is set, its value will be used as the seed filename. Otherwise, the file is called \*(C`.rnd\*(C', found in platform dependent locations:

"On Windows (in order of preference)" 4
Item "On Windows (in order of preference)" .Vb 1 %HOME%, %USERPROFILE%, %SYSTEMROOT%, C:\e .Ve
"On \s-1VMS\s0" 4
Item "On VMS" .Vb 1 SYS$LOGIN: .Ve
"On all other systems" 4
Item "On all other systems" .Vb 1 $HOME .Ve

If $HOME (on non-Windows and non-VMS system) is not set either, or \fBnum is too small for the pathname, an error occurs.

"RETURN VALUES"
Header "RETURN VALUES" \fBRAND_load_file() returns the number of bytes read or -1 on error.

\fBRAND_write_file() returns the number of bytes written, or -1 if the bytes written were generated without appropriate seeding.

\fBRAND_file_name() returns a pointer to buf on success, and \s-1NULL\s0 on error.

"SEE ALSO"
Header "SEE ALSO" \fBRAND_add\|(3), \fBRAND_bytes\|(3), \s-1RAND\s0\|(7)
"COPYRIGHT"
Header "COPYRIGHT" Copyright 2000-2020 The OpenSSL Project Authors. All Rights Reserved.

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>.