Struct rand::rngs::OsRng

pub struct OsRng;

Available on crate feature getrandom only.

A random number generator that retrieves randomness from the operating system.

This is a zero-sized struct. It can be freely constructed with OsRng.

The implementation is provided by the getrandom crate. Refer to getrandom documentation for details.

This struct is available as rand_core::OsRng and as rand::rngs::OsRng. In both cases, this requires the crate feature getrandom or std (enabled by default in rand but not in rand_core).

Blocking and error handling

It is possible that when used during early boot the first call to OsRng will block until the system’s RNG is initialised. It is also possible (though highly unlikely) for OsRng to fail on some platforms, most likely due to system mis-configuration.

After the first successful call, it is highly unlikely that failures or significant delays will occur (although performance should be expected to be much slower than a user-space PRNG).

Usage example

use rand_core::{RngCore, OsRng};

let mut key = [0u8; 16];
OsRng.fill_bytes(&mut key);
let random_u64 = OsRng.next_u64();

Trait Implementations

impl Clone for OsRng

fn clone(&self) -> OsRng

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for OsRng

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl Default for OsRng

fn default() -> OsRng

Returns the “default value” for a type.

impl RngCore for OsRng

fn next_u32(&mut self) -> u32

Return the next random u32.

fn next_u64(&mut self) -> u64

Return the next random u64.

fn fill_bytes(&mut self, dest: &mut [u8])

Fill dest with random data.

fn try_fill_bytes(&mut self, dest: &mut [u8]) -> Result<(), Error>

Fill dest entirely with random data.

fn read_adapter(&mut self) -> RngReadAdapter<'_, Self>

where Self: Sized,

Convert an RngCore to a RngReadAdapter.

impl Copy for OsRng

impl CryptoRng for OsRng