mirror of https://github.com/openssl/openssl.git
88 lines
2.3 KiB
Plaintext
88 lines
2.3 KiB
Plaintext
=pod
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=head1 NAME
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RAND_load_file, RAND_write_file, RAND_file_name - PRNG seed file
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=head1 SYNOPSIS
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#include <openssl/rand.h>
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int RAND_load_file(const char *filename, long max_bytes);
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int RAND_write_file(const char *filename);
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const char *RAND_file_name(char *buf, size_t num);
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=head1 DESCRIPTION
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RAND_load_file() reads a number of bytes from file B<filename> and
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adds them to the PRNG. If B<max_bytes> is nonnegative,
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up to B<max_bytes> are read;
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if B<max_bytes> is -1, the complete file is read.
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Do not load the same file multiple times unless its contents have
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been updated by RAND_write_file() between reads.
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Also, note that B<filename> should be adequately protected so that an
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attacker cannot replace or examine the contents.
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If B<filename> is not a regular file, then user is considered to be
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responsible for any side effects, e.g. non-anticipated blocking or
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capture of controlling terminal.
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RAND_write_file() writes a number of random bytes (currently 128) to
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file B<filename> which can be used to initialize the PRNG by calling
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RAND_load_file() in a later session.
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RAND_file_name() generates a default path for the random seed
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file. B<buf> points to a buffer of size B<num> in which to store the
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filename.
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On all systems, if the environment variable B<RANDFILE> is set, its
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value will be used as the seed filename.
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Otherwise, the file is called C<.rnd>, found in platform dependent locations:
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=over 4
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=item On Windows (in order of preference)
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%HOME%, %USERPROFILE%, %SYSTEMROOT%, C:\
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=item On VMS
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SYS$LOGIN:
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=item On all other systems
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$HOME
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=back
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If C<$HOME> (on non-Windows and non-VMS system) is not set either, or
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B<num> is too small for the pathname, an error occurs.
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=head1 RETURN VALUES
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RAND_load_file() returns the number of bytes read or -1 on error.
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RAND_write_file() returns the number of bytes written, or -1 if the
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bytes written were generated without appropriate seeding.
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RAND_file_name() returns a pointer to B<buf> on success, and NULL on
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error.
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=head1 SEE ALSO
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L<RAND_add(3)>,
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L<RAND_bytes(3)>,
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L<RAND(7)>
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=head1 COPYRIGHT
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Copyright 2000-2020 The OpenSSL Project Authors. All Rights Reserved.
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Licensed under the Apache License 2.0 (the "License"). You may not use
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this file except in compliance with the License. You can obtain a copy
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in the file LICENSE in the source distribution or at
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L<https://www.openssl.org/source/license.html>.
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=cut
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