NAME
getentropy —
get entropy
SYNOPSIS
#include
<unistd.h>
int
getentropy(void
*buf, size_t
buflen);
DESCRIPTION
getentropy()
fills a buffer with high-quality entropy, which can be used as input for
process-context pseudorandom generators like
arc4random(3).
The maximum buffer size permitted is
GETENTROPY_MAX (256) bytes.
getentropy()
is not intended for regular code; use the
arc4random(3) family of functions instead.
The high-quality entropy data is provided by the random(4) subsystem.
RETURN VALUES
Upon successful completion, the value 0 is returned; otherwise the value -1 is returned and the global variable errno is set to indicate the error.
ERRORS
getentropy() will succeed unless:
SEE ALSO
STANDARDS
The getentropy() function conforms to
IEEE Std 1003.1-2024 (“POSIX.1”).
HISTORY
The getentropy() function appeared in
OpenBSD 5.6.