NAME

getentropy — get entropy

SYNOPSIS

#include <unistd.h>

int
getentropy(void *buf, size_t buflen);

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.

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.

getentropy() will succeed unless:

The getentropy() function conforms to.

The getentropy() function appeared in OpenBSD 5.6.