Struct 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

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.

impl Copy for OsRng

impl CryptoRng for OsRng

Layout

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...) attributes. Please see the Rust Reference's “Type Layout” chapter for details on type layout guarantees.

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