Struct rand::chacha::ChaChaRng [] [src]

pub struct ChaChaRng {
    buffer: [u32; STATE_WORDS],
    state: [u32; STATE_WORDS],
    index: usize,
}
Unstable (rand)

: use rand from crates.io

A random number generator that uses the ChaCha20 algorithm [1].

The ChaCha algorithm is widely accepted as suitable for cryptographic purposes, but this implementation has not been verified as such. Prefer a generator like OsRng that defers to the operating system for cases that need high security.

[1]: D. J. Bernstein, ChaCha, a variant of Salsa20

Fields

buffer
Unstable (rand)

: use rand from crates.io

state
Unstable (rand)

: use rand from crates.io

index
Unstable (rand)

: use rand from crates.io

Methods

impl ChaChaRng

fn new_unseeded() -> ChaChaRng

Unstable (rand)

: use rand from crates.io

Create an ChaCha random number generator using the default fixed key of 8 zero words.

fn set_counter(&mut self, counter_low: u64, counter_high: u64)

Unstable (rand)

: use rand from crates.io

Sets the internal 128-bit ChaCha counter to a user-provided value. This permits jumping arbitrarily ahead (or backwards) in the pseudorandom stream.

Since the nonce words are used to extend the counter to 128 bits, users wishing to obtain the conventional ChaCha pseudorandom stream associated with a particular nonce can call this function with arguments 0, desired_nonce.

fn init(&mut self, key: &[u32; KEY_WORDS])

Unstable (rand)

: use rand from crates.io

Initializes self.state with the appropriate key and constants

We deviate slightly from the ChaCha specification regarding the nonce, which is used to extend the counter to 128 bits. This is provably as strong as the original cipher, though, since any distinguishing attack on our variant also works against ChaCha with a chosen-nonce. See the XSalsa20 [1] security proof for a more involved example of this.

The modified word layout is: text constant constant constant constant key key key key key key key key counter counter counter counter [1]: Daniel J. Bernstein. Extending the Salsa20 nonce.

fn update(&mut self)

Unstable (rand)

: use rand from crates.io

Refill the internal output buffer (self.buffer)

Trait Implementations

impl Rng for ChaChaRng

fn next_u32(&mut self) -> u32

fn next_u64(&mut self) -> u64

fn next_f32(&mut self) -> f32

fn next_f64(&mut self) -> f64

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

fn gen<T: Rand>(&mut self) -> T

fn gen_iter<'a, T: Rand>(&'a mut self) -> Generator<'a, T, Self>

fn gen_range<T: PartialOrd + SampleRange>(&mut self, low: T, high: T) -> T

fn gen_weighted_bool(&mut self, n: usize) -> bool

fn gen_ascii_chars<'a>(&'a mut self) -> AsciiGenerator<'a, Self>

fn choose<'a, T>(&mut self, values: &'a [T]) -> Option<&'a T>

fn shuffle<T>(&mut self, values: &mut [T])

impl<'a> SeedableRng<&'a [u32]> for ChaChaRng

fn reseed(&mut self, seed: &'a [u32])

fn from_seed(seed: &'a [u32]) -> ChaChaRng

impl Rand for ChaChaRng

fn rand<R: Rng>(other: &mut R) -> ChaChaRng

Derived Implementations

impl Clone for ChaChaRng

fn clone(&self) -> ChaChaRng

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

impl Copy for ChaChaRng