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-=pod
-
-=head1 NAME
-
-RAND_add, RAND_seed, RAND_status, RAND_event, RAND_screen - add
-entropy to the PRNG
-
-=head1 SYNOPSIS
-
- #include <openssl/rand.h>
-
- void RAND_seed(const void *buf, int num);
-
- void RAND_add(const void *buf, int num, double entropy);
-
- int RAND_status(void);
-
- int RAND_event(UINT iMsg, WPARAM wParam, LPARAM lParam);
- void RAND_screen(void);
-
-=head1 DESCRIPTION
-
-RAND_add() mixes the B<num> bytes at B<buf> into the PRNG state. Thus,
-if the data at B<buf> are unpredictable to an adversary, this
-increases the uncertainty about the state and makes the PRNG output
-less predictable. Suitable input comes from user interaction (random
-key presses, mouse movements) and certain hardware events. The
-B<entropy> argument is (the lower bound of) an estimate of how much
-randomness is contained in B<buf>, measured in bytes. Details about
-sources of randomness and how to estimate their entropy can be found
-in the literature, e.g. RFC 1750.
-
-RAND_add() may be called with sensitive data such as user entered
-passwords. The seed values cannot be recovered from the PRNG output.
-
-OpenSSL makes sure that the PRNG state is unique for each thread. On
-systems that provide C</dev/urandom>, the randomness device is used
-to seed the PRNG transparently. However, on all other systems, the
-application is responsible for seeding the PRNG by calling RAND_add(),
-L<RAND_egd(3)|RAND_egd(3)>
-or L<RAND_load_file(3)|RAND_load_file(3)>.
-
-RAND_seed() is equivalent to RAND_add() when B<num == entropy>.
-
-RAND_event() collects the entropy from Windows events such as mouse
-movements and other user interaction. It should be called with the
-B<iMsg>, B<wParam> and B<lParam> arguments of I<all> messages sent to
-the window procedure. It will estimate the entropy contained in the
-event message (if any), and add it to the PRNG. The program can then
-process the messages as usual.
-
-The RAND_screen() function is available for the convenience of Windows
-programmers. It adds the current contents of the screen to the PRNG.
-For applications that can catch Windows events, seeding the PRNG by
-calling RAND_event() is a significantly better source of
-randomness. It should be noted that both methods cannot be used on
-servers that run without user interaction.
-
-=head1 RETURN VALUES
-
-RAND_status() and RAND_event() return 1 if the PRNG has been seeded
-with enough data, 0 otherwise.
-
-The other functions do not return values.
-
-=head1 SEE ALSO
-
-L<rand(3)|rand(3)>, L<RAND_egd(3)|RAND_egd(3)>,
-L<RAND_load_file(3)|RAND_load_file(3)>, L<RAND_cleanup(3)|RAND_cleanup(3)>
-
-=head1 HISTORY
-
-RAND_seed() and RAND_screen() are available in all versions of SSLeay
-and OpenSSL. RAND_add() and RAND_status() have been added in OpenSSL
-0.9.5, RAND_event() in OpenSSL 0.9.5a.
-
-=cut