[−][src]Struct rand::rngs::EntropyRng

pub struct EntropyRng { /* fields omitted */ }

An interface returning random data from external source(s), provided specifically for securely seeding algorithmic generators (PRNGs).

Where possible, EntropyRng retrieves random data from the operating system's interface for random numbers (OsRng); if that fails it will fall back to the JitterRng entropy collector. In the latter case it will still try to use OsRng on the next usage.

If no secure source of entropy is available EntropyRng will panic on use; i.e. it should never output predictable data.

This is either a little slow (OsRng requires a system call) or extremely slow (JitterRng must use significant CPU time to generate sufficient jitter); for better performance it is common to seed a local PRNG from external entropy then primarily use the local PRNG (thread_rng is provided as a convenient, local, automatically-seeded CSPRNG).

Panics

On most systems, like Windows, Linux, macOS and *BSD on common hardware, it is highly unlikely for both OsRng and JitterRng to fail. But on combinations like webassembly without Emscripten or stdweb both sources are unavailable. If both sources fail, only try_fill_bytes is able to report the error, and only the one from OsRng. The other RngCore methods will panic in case of an error.

Methods

impl EntropyRng
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pub fn new() -> Self
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Create a new EntropyRng.

This method will do no system calls or other initialization routines, those are done on first use. This is done to make new infallible, and try_fill_bytes the only place to report errors.

Trait Implementations

impl Default for EntropyRng
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impl Debug for EntropyRng
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impl CryptoRng for EntropyRng
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impl RngCore for EntropyRng
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Auto Trait Implementations

impl Send for EntropyRng

impl Sync for EntropyRng

Blanket Implementations

impl<R> Rng for R where
    R: RngCore + ?Sized, 
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fn gen<T>(&mut self) -> T where
    Standard: Distribution<T>, 
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Return a random value supporting the [Standard] distribution. Read more

fn gen_range<T: PartialOrd + SampleUniform>(&mut self, low: T, high: T) -> T
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Generate a random value in the range [low, high), i.e. inclusive of low and exclusive of high. Read more

fn sample<T, D: Distribution<T>>(&mut self, distr: D) -> T
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Sample a new value, using the given distribution. Read more

ⓘImportant traits for DistIter<'a, D, R, T>
fn sample_iter<'a, T, D: Distribution<T>>(
    &'a mut self,
    distr: &'a D
) -> DistIter<'a, D, Self, T> where
    Self: Sized, 
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Create an iterator that generates values using the given distribution. Read more

fn fill<T: AsByteSliceMut + ?Sized>(&mut self, dest: &mut T)
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Fill dest entirely with random bytes (uniform value distribution), where dest is any type supporting [AsByteSliceMut], namely slices and arrays over primitive integer types (i8, i16, u32, etc.). Read more

fn try_fill<T: AsByteSliceMut + ?Sized>(
    &mut self,
    dest: &mut T
) -> Result<(), Error>
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Fill dest entirely with random bytes (uniform value distribution), where dest is any type supporting [AsByteSliceMut], namely slices and arrays over primitive integer types (i8, i16, u32, etc.). Read more

fn gen_bool(&mut self, p: f64) -> bool
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Return a bool with a probability p of being true. Read more

fn choose<'a, T>(&mut self, values: &'a [T]) -> Option<&'a T>
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Return a random element from values. Read more

fn choose_mut<'a, T>(&mut self, values: &'a mut [T]) -> Option<&'a mut T>
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Return a mutable pointer to a random element from values. Read more

fn shuffle<T>(&mut self, values: &mut [T])
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Shuffle a mutable slice in place. Read more

ⓘImportant traits for Generator<T, R>
fn gen_iter<T>(&mut self) -> Generator<T, &mut Self> where
    Standard: Distribution<T>, 
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Deprecated since 0.5.0:

use Rng::sample_iter(&Standard) instead

Return an iterator that will yield an infinite number of randomly generated items. Read more

fn gen_weighted_bool(&mut self, n: u32) -> bool
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Deprecated since 0.5.0:

use gen_bool instead

Return a bool with a 1 in n chance of true Read more

ⓘImportant traits for AsciiGenerator<R>
fn gen_ascii_chars(&mut self) -> AsciiGenerator<&mut Self>
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Deprecated since 0.5.0:

use sample_iter(&Alphanumeric) instead

Return an iterator of random characters from the set A-Z,a-z,0-9. Read more

impl<T, U> Into for T where
    U: From<T>, 
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impl<T> From for T
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impl<T, U> TryFrom for T where
    T: From<U>, 
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type Error = !

🔬 This is a nightly-only experimental API. (try_from)

The type returned in the event of a conversion error.

impl<T> Borrow for T where
    T: ?Sized, 
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impl<T> Any for T where
    T: 'static + ?Sized, 
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impl<T, U> TryInto for T where
    U: TryFrom<T>, 
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type Error = <U as TryFrom<T>>::Error

🔬 This is a nightly-only experimental API. (try_from)

The type returned in the event of a conversion error.

impl<T> BorrowMut for T where
    T: ?Sized, 
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