• NAME
• SYNOPSIS
• DESCRIPTION
• RETURN VALUES
• SEE ALSO
• HISTORY
• COPYRIGHT

NAME

RAND_add, RAND_poll, RAND_seed, RAND_status, RAND_event, RAND_screen, RAND_keep_random_devices_open - add randomness to the PRNG or get its status

SYNOPSIS

 #include <openssl/rand.h>
 
 int RAND_status(void);
 int RAND_poll();
 
 void RAND_add(const void *buf, int num, double randomness);
 void RAND_seed(const void *buf, int num);
 
 void RAND_keep_random_devices_open(int keep);

Deprecated since OpenSSL 1.1.0, can be hidden entirely by defining OPENSSL_API_COMPAT with a suitable version value, see int RAND_event(UINT iMsg, WPARAM wParam, LPARAM lParam); void RAND_screen(void);

DESCRIPTION

These functions can be used to seed the random generator and to check its seeded state. In general, manual (re-)seeding of the default OpenSSL random generator (RAND(7) for more details.

RAND_status() indicates whether or not the random generator has been sufficiently seeded. If not, functions such as RAND(7) for more details.

RAND_add() mixes the num bytes at buf into the internal state of the random generator. This function will not normally be needed, as mentioned above. The randomness argument is an estimate of how much randomness is contained in buf, in bytes, and should be a number between zero and num. Details about sources of randomness and how to estimate their randomness can be found in the literature; for example [NIST SP 800-90B]. The content of buf cannot be recovered from subsequent random generator output. Applications that intend to save and restore random state in an external file should consider using RAND_DRBG(7).

RAND_seed() is equivalent to RAND_add() with randomness set to num.

RAND_keep_random_devices_open() is used to control file descriptor usage by the random seed sources. Some seed sources maintain open file descriptors by default, which allows such sources to operate in a chroot(2) jail without the associated device nodes being available. When the keep argument is zero, this call disables the retention of file descriptors. Conversely, a nonzero argument enables the retention of file descriptors. This function is usually called during initialization and it takes effect immediately.

RAND_event() and RAND_screen() are equivalent to RAND_poll() and exist for compatibility reasons only. See HISTORY section below.

RETURN VALUES

RAND_status() returns 1 if the random generator has been seeded with enough data, 0 otherwise.

RAND_poll() returns 1 if it generated seed data, 0 otherwise.

RAND_event() returns RAND_status().

The other functions do not return values.

SEE ALSO

RAND_egd(3), RAND(7) HISTORY

RAND_event() and RAND_screen() were deprecated in OpenSSL 1.1.0 and should not be used.

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.