Struct neptune::poseidon::Poseidon

pub struct Poseidon<'a, F, A = U2>where
    F: PrimeField,
    A: Arity<F>,{
    pub elements: GenericArray<F, A::ConstantsSize>,
    /* private fields */
}

Holds preimage, some utility offsets and counters along with the reference to PoseidonConstants required for hashing. Poseidon is parameterized by ff::PrimeField and Arity, which should be similar to PoseidonConstants.

Poseidon accepts input elements set with length equal or less than Arity.

Fields

elements: GenericArray<F, A::ConstantsSize>

the elements to permute

Implementations

impl<'a, F, A> Poseidon<'a, F, A>where F: PrimeField, A: Arity<F>,

pub fn new(constants: &'a PoseidonConstants<F, A>) -> Self

Creates Poseidon instance using provided PoseidonConstants as input. Underlying set of elements are initialized and domain_tag from PoseidonConstants is used as zero element in the set. Therefore, hashing is eventually performed over Arity + 1 elements in fact, while Arity elements are occupied by preimage data.

Example

use neptune::poseidon::PoseidonConstants;
use neptune::poseidon::Poseidon;
use pasta_curves::Fp;
use ff::Field;
use generic_array::typenum::U8;

let constants: PoseidonConstants<Fp, U8> = PoseidonConstants::new();
let poseidon = Poseidon::<Fp, U8>::new(&constants);

assert_eq!(poseidon.elements.len(), 9);
for index in 1..9 {
    assert_eq!(poseidon.elements[index], Fp::ZERO);
}

pub fn new_with_preimage( preimage: &[F], constants: &'a PoseidonConstants<F, A> ) -> Self

Creates Poseidon instance using provided preimage and PoseidonConstants as input. Doesn’t support PoseidonConstants with HashType::VariableLength. It is assumed that size of input preimage set can’t be greater than Arity.

Example

use neptune::poseidon::PoseidonConstants;
use neptune::poseidon::Poseidon;
use pasta_curves::Fp;
use ff::Field;
use generic_array::typenum::U2;

let preimage_set_length = 1;
let constants: PoseidonConstants<Fp, U2> = PoseidonConstants::new_constant_length(preimage_set_length);

let preimage = vec![Fp::from(u64::MAX); preimage_set_length];

let mut poseidon = Poseidon::<Fp, U2>::new_with_preimage(&preimage, &constants);

assert_eq!(constants.width(), 3);
assert_eq!(poseidon.elements.len(), constants.width());
assert_eq!(poseidon.elements[1], Fp::from(u64::MAX));
assert_eq!(poseidon.elements[2], Fp::ZERO);

pub fn set_preimage(&mut self, preimage: &[F])

Replaces the elements with the provided optional items.

Panics

Panics if the provided slice is not equal to the arity.

Example

use neptune::poseidon::PoseidonConstants;
use neptune::poseidon::Poseidon;
use pasta_curves::Fp;
use ff::Field;
use generic_array::typenum::U2;

let constants: PoseidonConstants<Fp, U2> = PoseidonConstants::new_constant_length(1);
let preimage = vec![Fp::from(u64::MAX)];

let mut poseidon = Poseidon::<Fp, U2>::new_with_preimage(&preimage, &constants);

assert_eq!(poseidon.elements.len(), constants.width());
assert_eq!(poseidon.elements[1], Fp::from(u64::MAX));
assert_eq!(poseidon.elements[2], Fp::ZERO);

let preimage = vec![Fp::from(u64::MIN), Fp::from(u64::MIN)];
poseidon.set_preimage(&preimage);
assert_eq!(poseidon.elements.len(), constants.width());
assert_eq!(poseidon.elements[1], Fp::from(u64::MIN)); // Now it's u64::MIN
assert_eq!(poseidon.elements[2], Fp::from(u64::MIN)); // Now it's u64::MIN

pub fn reset(&mut self)

Restore the initial state

pub fn input(&mut self, element: F) -> Result<usize, Error>

Adds one more field element of preimage to the underlying Poseidon buffer for further hashing. The returned usize represents the element position (within arity) for the input operation. Returns Error::FullBuffer if no more elements can be added for hashing.

Example

use neptune::poseidon::PoseidonConstants;
use neptune::poseidon::Poseidon;
use pasta_curves::Fp;
use ff::Field;
use generic_array::typenum::U2;

let constants: PoseidonConstants<Fp, U2> = PoseidonConstants::new_constant_length(1);

let mut poseidon = Poseidon::<Fp, U2>::new(&constants);
assert_eq!(poseidon.elements.len(), constants.width());
assert_eq!(poseidon.elements[1], Fp::ZERO);
assert_eq!(poseidon.elements[2], Fp::ZERO);

let pos = poseidon.input(Fp::from(u64::MAX)).expect("can't add one more element");

assert_eq!(pos, 1);
assert_eq!(poseidon.elements[1], Fp::from(u64::MAX));
assert_eq!(poseidon.elements[2], Fp::ZERO);

let pos = poseidon.input(Fp::from(u64::MAX)).expect("can't add one more element");

assert_eq!(pos, 2);
assert_eq!(poseidon.elements[1], Fp::from(u64::MAX));
assert_eq!(poseidon.elements[2], Fp::from(u64::MAX));

// poseidon.input(Fp::from(u64::MAX)).expect("can't add one more element"); // panic !!!

pub fn hash_in_mode(&mut self, mode: HashMode) -> F

Performs hashing using underlying Poseidon buffer of the preimage’ field elements using provided HashMode. Always outputs digest expressed as a single field element of concrete type specified upon PoseidonConstants and Poseidon instantiations.

Example

use neptune::poseidon::{HashMode, PoseidonConstants};
use neptune::poseidon::Poseidon;
use pasta_curves::Fp;
use ff::Field;
use generic_array::typenum::U2;

let constants: PoseidonConstants<Fp, U2> = PoseidonConstants::new();

let mut poseidon = Poseidon::<Fp, U2>::new(&constants);

poseidon.input(Fp::from(u64::MAX)).expect("can't add one more element");

let digest = poseidon.hash_in_mode(HashMode::Correct);

assert_ne!(digest, Fp::ZERO); // digest has `Fp` type

pub fn hash(&mut self) -> F

Performs hashing using underlying Poseidon buffer of the preimage’ field elements in default (optimized) mode. Always outputs digest expressed as a single field element of concrete type specified upon PoseidonConstants and Poseidon instantiations.

Example

use neptune::poseidon::PoseidonConstants;
use neptune::poseidon::Poseidon;
use pasta_curves::Fp;
use ff::Field;
use generic_array::typenum::U2;

let constants: PoseidonConstants<Fp, U2> = PoseidonConstants::new();

let mut poseidon = Poseidon::<Fp, U2>::new(&constants);

poseidon.input(Fp::from(u64::MAX)).expect("can't add one more element");

let digest = poseidon.hash();

assert_ne!(digest, Fp::ZERO); // digest has `Fp` type

pub fn extract_output(&self) -> F

Returns 1-th element from underlying Poseidon buffer. This function is important, since according to Poseidon design, after performing hashing, output digest will be stored at 1-st place of underlying buffer.

Example

use neptune::poseidon::PoseidonConstants;
use neptune::poseidon::Poseidon;
use pasta_curves::Fp;
use ff::Field;
use generic_array::typenum::U2;

let constants: PoseidonConstants<Fp, U2> = PoseidonConstants::new();

let mut poseidon = Poseidon::<Fp, U2>::new(&constants);

poseidon.input(Fp::from(u64::MAX)).expect("can't add one more element");

let output = poseidon.extract_output();

assert_eq!(poseidon.elements[1], Fp::from(u64::MAX));
assert_eq!(output, Fp::from(u64::MAX)); // output == input

let digest = poseidon.hash();

let output = poseidon.extract_output();

assert_eq!(poseidon.elements[1], output);
assert_eq!(digest, output); // output == digest

pub fn hash_optimized_static(&mut self) -> F

Performs hashing using underlying Poseidon buffer of the preimage’ field elements using HashMode::OptimizedStatic mode. Always outputs digest expressed as a single field element of concrete type specified upon PoseidonConstants and Poseidon instantiations.

Example

use neptune::poseidon::PoseidonConstants;
use neptune::poseidon::Poseidon;
use pasta_curves::Fp;
use ff::Field;
use generic_array::typenum::U2;

let constants: PoseidonConstants<Fp, U2> = PoseidonConstants::new();

let mut poseidon = Poseidon::<Fp, U2>::new(&constants);

poseidon.input(Fp::from(u64::MAX)).expect("can't add one more element");

let digest = poseidon.hash_optimized_static();

assert_ne!(digest, Fp::ZERO); // digest has `Fp` type

Trait Implementations

impl<'a, F, A> Clone for Poseidon<'a, F, A>where F: PrimeField + Clone, A: Arity<F> + Clone, A::ConstantsSize: Clone,

fn clone(&self) -> Poseidon<'a, F, A>

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<'a, F, A> Debug for Poseidon<'a, F, A>where F: PrimeField + Debug, A: Arity<F> + Debug, A::ConstantsSize: Debug,

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'a, F, A> PartialEq for Poseidon<'a, F, A>where F: PrimeField + PartialEq, A: Arity<F> + PartialEq, A::ConstantsSize: PartialEq,

fn eq(&self, other: &Poseidon<'a, F, A>) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<'a, Scalar, A> SizedWitness<Scalar> for Poseidon<'a, Scalar, A>where Scalar: PrimeField, A: Arity<Scalar>,

fn num_constraints(&self) -> usize

fn num_inputs(&self) -> usize

fn num_aux(&self) -> usize

fn generate_witness_into( &mut self, aux: &mut [Scalar], _inputs: &mut [Scalar] ) -> Scalar

fn generate_witness(&mut self) -> (Vec<Scalar>, Vec<Scalar>, Scalar)

fn generate_witness_into_cs<CS>(&mut self, cs: &mut CS) -> Scalarwhere CS: ConstraintSystem<Scalar>,

impl<'a, F, A> Eq for Poseidon<'a, F, A>where F: PrimeField + Eq, A: Arity<F> + Eq, A::ConstantsSize: Eq,

impl<'a, F, A> StructuralEq for Poseidon<'a, F, A>where F: PrimeField, A: Arity<F>,

impl<'a, F, A> StructuralPartialEq for Poseidon<'a, F, A>where F: PrimeField, A: Arity<F>,