[−][src]Struct rand::prng::isaac64::Isaac64Rng
A random number generator that uses ISAAC-64, the 64-bit variant of the ISAAC algorithm.
ISAAC stands for "Indirection, Shift, Accumulate, Add, and Count" which are the principal bitwise operations employed. It is the most advanced of a series of array based random number generator designed by Robert Jenkins in 19961.
ISAAC-64 is mostly similar to ISAAC. Because it operates on 64-bit integers instead of 32-bit, it uses twice as much memory to hold its state and results. Also it uses different constants for shifts and indirect indexing, optimized to give good results for 64bit arithmetic.
ISAAC-64 is notably fast and produces excellent quality random numbers for non-cryptographic applications.
In spite of being designed with cryptographic security in mind, ISAAC hasn't
been stringently cryptanalyzed and thus cryptographers do not not
consensually trust it to be secure. When looking for a secure RNG, prefer
Hc128Rng
instead, which, like ISAAC, is an array-based RNG and one of
the stream-ciphers selected the by eSTREAM contest.
Overview of the ISAAC-64 algorithm:
(in pseudo-code)
Input: a, b, c, s[256] // state
Output: r[256] // results
mix(a,i) = !(a ^ a << 21) if i = 0 mod 4
a ^ a >> 5 if i = 1 mod 4
a ^ a << 12 if i = 2 mod 4
a ^ a >> 33 if i = 3 mod 4
c = c + 1
b = b + c
for i in 0..256 {
x = s_[i]
a = mix(a,i) + s[i+128 mod 256]
y = a + b + s[x>>3 mod 256]
s[i] = y
b = x + s[y>>11 mod 256]
r[i] = b
}
This implementation uses BlockRng64
to implement the RngCore
methods.
See for more information the documentation of IsaacRng
.
-
Bob Jenkins, ISAAC and RC4 ↩
Methods
impl Isaac64Rng
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pub fn new_unseeded() -> Self
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use the FromEntropy or SeedableRng trait
Create a 64-bit ISAAC random number generator using the default fixed seed.
DEPRECATED. Isaac64Rng::new_from_u64(0)
will produce identical results.
pub fn new_from_u64(seed: u64) -> Self
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use SeedableRng::seed_from_u64 instead
Create an ISAAC-64 random number generator using an u64
as seed.
If seed == 0
this will produce the same stream of random numbers as
the reference implementation when used unseeded.
Trait Implementations
impl Clone for Isaac64Rng
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fn clone(&self) -> Isaac64Rng
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fn clone_from(&mut self, source: &Self)
1.0.0[src]
Performs copy-assignment from source
. Read more
impl Debug for Isaac64Rng
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impl RngCore for Isaac64Rng
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fn next_u32(&mut self) -> u32
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fn next_u64(&mut self) -> u64
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fn fill_bytes(&mut self, dest: &mut [u8])
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fn try_fill_bytes(&mut self, dest: &mut [u8]) -> Result<(), Error>
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impl SeedableRng for Isaac64Rng
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type Seed = <Isaac64Core as SeedableRng>::Seed
Seed type, which is restricted to types mutably-dereferencable as u8
arrays (we recommend [u8; N]
for some N
). Read more
fn from_seed(seed: Self::Seed) -> Self
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fn seed_from_u64(seed: u64) -> Self
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Create an ISAAC random number generator using an u64
as seed.
If seed == 0
this will produce the same stream of random numbers as
the reference implementation when used unseeded.
fn from_rng<S: RngCore>(rng: S) -> Result<Self, Error>
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Auto Trait Implementations
impl Send for Isaac64Rng
impl Sync for Isaac64Rng
Blanket Implementations
impl<R> Rng for R where
R: RngCore + ?Sized,
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R: RngCore + ?Sized,
fn gen<T>(&mut self) -> T where
Standard: Distribution<T>,
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Standard: Distribution<T>,
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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&'a mut self,
distr: &'a D
) -> DistIter<'a, D, Self, T> where
Self: Sized,
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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&mut self,
dest: &mut T
) -> Result<(), Error>
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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Standard: Distribution<T>,
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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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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use sample_iter(&Alphanumeric) instead
Return an iterator of random characters from the set A-Z,a-z,0-9. Read more
impl<R> FromEntropy for R where
R: SeedableRng,
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R: SeedableRng,
fn from_entropy() -> R
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impl<T> From for T
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impl<T, U> Into for T where
U: From<T>,
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U: From<T>,
impl<T> ToOwned for T where
T: Clone,
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T: Clone,
impl<T, U> TryFrom for T where
T: From<U>,
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T: From<U>,
type Error = !
try_from
)The type returned in the event of a conversion error.
fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>
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impl<T> Borrow for T where
T: ?Sized,
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T: ?Sized,
impl<T> BorrowMut for T where
T: ?Sized,
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T: ?Sized,
fn borrow_mut(&mut self) -> &mut T
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impl<T, U> TryInto for T where
U: TryFrom<T>,
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U: TryFrom<T>,
type Error = <U as TryFrom<T>>::Error
try_from
)The type returned in the event of a conversion error.
fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>
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impl<T> Any for T where
T: 'static + ?Sized,
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T: 'static + ?Sized,