5 RAND_add, RAND_seed, RAND_status, RAND_event, RAND_screen - add
10 #include <openssl/rand.h>
12 void RAND_seed(const void *buf, int num);
14 void RAND_add(const void *buf, int num, double randomness);
16 int RAND_status(void);
18 #if OPENSSL_API_COMPAT < 0x10100000L
19 int RAND_event(UINT iMsg, WPARAM wParam, LPARAM lParam);
20 void RAND_screen(void);
25 RAND_add() mixes the B<num> bytes at B<buf> into the PRNG state. Thus,
26 if the data at B<buf> are unpredictable to an adversary, this
27 increases the uncertainty about the state and makes the PRNG output
28 less predictable. Suitable input comes from user interaction (random
29 key presses, mouse movements) and certain hardware events. The
30 B<randomness> argument is an estimate of how much randomness is contained in
31 B<buf>, in bytes, and should be a number between zero and B<num>.
32 Details about sources of randomness and how to estimate their randomness
33 can be found in the literature; for example IETF RFC 4086.
35 RAND_add() may be called with sensitive data such as user entered
36 passwords. The seed values cannot be recovered from the PRNG output.
38 RAND_seed() is equivalent to RAND_add() with B<randomness> set to B<num>.
40 On systems that provide C</dev/urandom> or similar source of randomess,
42 to seed the PRNG transparently. On older systems, however, it might
43 be necessary to use RAND_add(), L<RAND_egd(3)> or L<RAND_load_file(3)>.
45 RAND_event() and RAND_screen() are deprecated and should not be called.
49 RAND_status() returns 1 if the PRNG has been seeded
50 with enough data, 0 otherwise.
52 RAND_event() calls RAND_poll() and returns RAND_status().
54 RAND_screen calls RAND_poll().
56 The other functions do not return values.
60 RAND_event() and RAND_screen() are deprecated since OpenSSL
61 1.1.0. Use the functions described above instead.
65 L<RAND_bytes(3)>, L<RAND_egd(3)>,
70 Copyright 2000-2017 The OpenSSL Project Authors. All Rights Reserved.
72 Licensed under the OpenSSL license (the "License"). You may not use
73 this file except in compliance with the License. You can obtain a copy
74 in the file LICENSE in the source distribution or at
75 L<https://www.openssl.org/source/license.html>.