# [−][src]Struct rand_isaac::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 1996^{1}.

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`

from the `rand_hc`

crate instead, which, like ISAAC, is an
array-based RNG and one of the stream-ciphers selected the by eSTREAM

## 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*↩

## Trait Implementations

`impl Debug for Isaac64Rng`

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`impl Clone for Isaac64Rng`

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`fn clone(&self) -> Isaac64Rng`

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

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Performs copy-assignment from `source`

. Read more

`impl Serialize for Isaac64Rng`

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`fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error> where`

__S: Serializer,

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__S: Serializer,

`impl<'de> Deserialize<'de> for Isaac64Rng`

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`fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error> where`

__D: Deserializer<'de>,

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__D: Deserializer<'de>,

`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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`fn from_entropy() -> Self`

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Creates a new instance of the RNG seeded via [`getrandom`

]. Read more

## Auto Trait Implementations

`impl Send for Isaac64Rng`

`impl Sync for Isaac64Rng`

`impl Unpin for Isaac64Rng`

`impl UnwindSafe for Isaac64Rng`

`impl RefUnwindSafe for Isaac64Rng`

## Blanket Implementations

`impl<T, U> TryFrom<U> for T where`

U: Into<T>,

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U: Into<T>,

`type Error = Infallible`

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, U> Into<U> for T where`

U: From<T>,

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U: From<T>,

`impl<T> From<T> for T`

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`impl<T, U> TryInto<U> for T where`

U: TryFrom<T>,

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U: TryFrom<T>,

`type Error = <U as TryFrom<T>>::Error`

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> Borrow<T> for T where`

T: ?Sized,

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T: ?Sized,

`impl<T> BorrowMut<T> for T where`

T: ?Sized,

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T: ?Sized,

`fn borrow_mut(&mut self) -> &mut T`

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`impl<T> Any for T where`

T: 'static + ?Sized,

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T: 'static + ?Sized,

`impl<T> ToOwned for T where`

T: Clone,

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T: Clone,

`type Owned = T`

The resulting type after obtaining ownership.

`fn to_owned(&self) -> T`

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`fn clone_into(&self, target: &mut T)`

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`impl<T> DeserializeOwned for T where`

T: Deserialize<'de>,

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T: Deserialize<'de>,