Struct rand::rngs::OsRng

pub struct OsRng;

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 only available when specifying the crate feature getrandom or std. When using the rand lib, it is also available as rand::rngs::OsRng.

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

pub fn clone(&self) -> OsRng

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Copy for OsRng

impl CryptoRng for OsRng

impl Debug for OsRng

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

Formats the value using the given formatter.

impl Default for OsRng

pub fn default() -> OsRng

Returns the “default value” for a type.

impl RngCore for OsRng

pub fn next_u32(&mut self) -> u32

Return the next random u32.

pub fn next_u64(&mut self) -> u64

Return the next random u64.

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

Fill dest with random data.

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

Fill dest entirely with random data.