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poseidon: Replace the `Duplex` struct with a `Sponge` struct 

The `Sponge` struct's API correctly enforces the properties of a sponge:
it can absorb an arbitrary number of elements, and then squeeze an
arbitrary number of elements, but cannot absorb after it has squeezed.

Co-authored-by: ying tong <yingtong@z.cash>
This commit is contained in:
Jack Grigg 2021-11-24 17:01:33 +00:00
parent b827298d42
commit 9f654005c7
3 changed files with 188 additions and 141 deletions
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157
src/circuit/gadget/poseidon.rs
View File

@ -3,6 +3,7 @@
use std::array;
use std::convert::TryInto;
use std::fmt;
use std::marker::PhantomData;
use halo2::{
arithmetic::FieldExt,
@ -13,7 +14,9 @@ use halo2::{
mod pow5;
pub use pow5::{Pow5Chip, Pow5Config, StateWord};
use crate::primitives::poseidon::{ConstantLength, Domain, Spec, Sponge, SpongeRate, State};
use crate::primitives::poseidon::{
Absorbing, ConstantLength, Domain, Spec, SpongeMode, SpongeRate, Squeezing, State,
};
/// The set of circuit instructions required to use the Poseidon permutation.
pub trait PoseidonInstructions<F: FieldExt, S: Spec<F, T, RATE>, const T: usize, const RATE: usize>:
@ -30,10 +33,10 @@ pub trait PoseidonInstructions<F: FieldExt, S: Spec<F, T, RATE>, const T: usize,
) -> Result<State<Self::Word, T>, Error>;
}
/// The set of circuit instructions required to use the [`Duplex`] and [`Hash`] gadgets.
/// The set of circuit instructions required to use the [`Sponge`] and [`Hash`] gadgets.
///
/// [`Hash`]: self::Hash
pub trait PoseidonDuplexInstructions<
pub trait PoseidonSpongeInstructions<
F: FieldExt,
S: Spec<F, T, RATE>,
const T: usize,
@ -91,9 +94,9 @@ impl<
}
}
fn poseidon_duplex<
fn poseidon_sponge<
F: FieldExt,
PoseidonChip: PoseidonDuplexInstructions<F, S, T, RATE>,
PoseidonChip: PoseidonSpongeInstructions<F, S, T, RATE>,
S: Spec<F, T, RATE>,
D: Domain<F, T, RATE>,
const T: usize,
@ -110,30 +113,32 @@ fn poseidon_duplex<
Ok(PoseidonChip::get_output(state))
}
/// A Poseidon duplex sponge.
/// A Poseidon sponge.
#[derive(Debug)]
pub struct Duplex<
pub struct Sponge<
F: FieldExt,
PoseidonChip: PoseidonDuplexInstructions<F, S, T, RATE>,
PoseidonChip: PoseidonSpongeInstructions<F, S, T, RATE>,
S: Spec<F, T, RATE>,
M: SpongeMode,
D: Domain<F, T, RATE>,
const T: usize,
const RATE: usize,
> {
chip: PoseidonChip,
sponge: Sponge<PoseidonChip::Word, RATE>,
mode: M,
state: State<PoseidonChip::Word, T>,
domain: D,
_marker: PhantomData<M>,
}
impl<
F: FieldExt,
PoseidonChip: PoseidonDuplexInstructions<F, S, T, RATE>,
PoseidonChip: PoseidonSpongeInstructions<F, S, T, RATE>,
S: Spec<F, T, RATE>,
D: Domain<F, T, RATE>,
const T: usize,
const RATE: usize,
> Duplex<F, PoseidonChip, S, D, T, RATE>
> Sponge<F, PoseidonChip, S, Absorbing<PoseidonChip::Word, RATE>, D, T, RATE>
{
/// Constructs a new duplex sponge for the given Poseidon specification.
pub fn new(
@ -142,9 +147,9 @@ impl<
domain: D,
) -> Result<Self, Error> {
chip.initial_state(&mut layouter, &domain)
.map(|state| Duplex {
.map(|state| Sponge {
chip,
sponge: Sponge::Absorbing(
mode: Absorbing(
(0..RATE)
.map(|_| None)
.collect::<Vec<_>>()
@ -153,6 +158,7 @@ impl<
),
state,
domain,
_marker: PhantomData::default(),
})
}
@ -162,84 +168,97 @@ impl<
mut layouter: impl Layouter<F>,
value: AssignedCell<F, F>,
) -> Result<(), Error> {
match self.sponge {
Sponge::Absorbing(ref mut input) => {
for entry in input.iter_mut() {
if entry.is_none() {
*entry = Some(value.into());
return Ok(());
}
}
// We've already absorbed as many elements as we can
let _ = poseidon_duplex(
&self.chip,
layouter.namespace(|| "PoseidonDuplex"),
&self.domain,
&mut self.state,
input,
)?;
self.sponge = Sponge::absorb(value.into());
}
Sponge::Squeezing(_) => {
// Drop the remaining output elements
self.sponge = Sponge::absorb(value.into());
for entry in self.mode.0.iter_mut() {
if entry.is_none() {
*entry = Some(value.into());
return Ok(());
}
}
// We've already absorbed as many elements as we can
let _ = poseidon_sponge(
&self.chip,
layouter.namespace(|| "PoseidonSponge"),
&self.domain,
&mut self.state,
&self.mode.0,
)?;
self.mode = Absorbing::init_with(value.into());
Ok(())
}
/// Transitions the sponge into its squeezing state.
#[allow(clippy::type_complexity)]
pub fn finish_absorbing(
mut self,
mut layouter: impl Layouter<F>,
) -> Result<Sponge<F, PoseidonChip, S, Squeezing<PoseidonChip::Word, RATE>, D, T, RATE>, Error>
{
let mode = Squeezing(poseidon_sponge(
&self.chip,
layouter.namespace(|| "PoseidonSponge"),
&self.domain,
&mut self.state,
&self.mode.0,
)?);
Ok(Sponge {
chip: self.chip,
mode,
state: self.state,
domain: self.domain,
_marker: PhantomData::default(),
})
}
}
impl<
F: FieldExt,
PoseidonChip: PoseidonSpongeInstructions<F, S, T, RATE>,
S: Spec<F, T, RATE>,
D: Domain<F, T, RATE>,
const T: usize,
const RATE: usize,
> Sponge<F, PoseidonChip, S, Squeezing<PoseidonChip::Word, RATE>, D, T, RATE>
{
/// Squeezes an element from the sponge.
pub fn squeeze(&mut self, mut layouter: impl Layouter<F>) -> Result<AssignedCell<F, F>, Error> {
loop {
match self.sponge {
Sponge::Absorbing(ref input) => {
self.sponge = Sponge::Squeezing(poseidon_duplex(
&self.chip,
layouter.namespace(|| "PoseidonDuplex"),
&self.domain,
&mut self.state,
input,
)?);
}
Sponge::Squeezing(ref mut output) => {
for entry in output.iter_mut() {
if let Some(inner) = entry.take() {
return Ok(inner.into());
}
}
// We've already squeezed out all available elements
self.sponge = Sponge::Absorbing(
(0..RATE)
.map(|_| None)
.collect::<Vec<_>>()
.try_into()
.unwrap(),
);
for entry in self.mode.0.iter_mut() {
if let Some(inner) = entry.take() {
return Ok(inner.into());
}
}
// We've already squeezed out all available elements
self.mode = Squeezing(poseidon_sponge(
&self.chip,
layouter.namespace(|| "PoseidonSponge"),
&self.domain,
&mut self.state,
&self.mode.0,
)?);
}
}
}
/// A Poseidon hash function, built around a duplex sponge.
/// A Poseidon hash function, built around a sponge.
#[derive(Debug)]
pub struct Hash<
F: FieldExt,
PoseidonChip: PoseidonDuplexInstructions<F, S, T, RATE>,
PoseidonChip: PoseidonSpongeInstructions<F, S, T, RATE>,
S: Spec<F, T, RATE>,
D: Domain<F, T, RATE>,
const T: usize,
const RATE: usize,
> {
duplex: Duplex<F, PoseidonChip, S, D, T, RATE>,
sponge: Sponge<F, PoseidonChip, S, Absorbing<PoseidonChip::Word, RATE>, D, T, RATE>,
}
impl<
F: FieldExt,
PoseidonChip: PoseidonDuplexInstructions<F, S, T, RATE>,
PoseidonChip: PoseidonSpongeInstructions<F, S, T, RATE>,
S: Spec<F, T, RATE>,
D: Domain<F, T, RATE>,
const T: usize,
@ -248,13 +267,13 @@ impl<
{
/// Initializes a new hasher.
pub fn init(chip: PoseidonChip, layouter: impl Layouter<F>, domain: D) -> Result<Self, Error> {
Duplex::new(chip, layouter, domain).map(|duplex| Hash { duplex })
Sponge::new(chip, layouter, domain).map(|sponge| Hash { sponge })
}
}
impl<
F: FieldExt,
PoseidonChip: PoseidonDuplexInstructions<F, S, T, RATE>,
PoseidonChip: PoseidonSpongeInstructions<F, S, T, RATE>,
S: Spec<F, T, RATE>,
const T: usize,
const RATE: usize,
@ -268,9 +287,11 @@ impl<
message: [AssignedCell<F, F>; L],
) -> Result<AssignedCell<F, F>, Error> {
for (i, value) in array::IntoIter::new(message).enumerate() {
self.duplex
self.sponge
.absorb(layouter.namespace(|| format!("absorb_{}", i)), value)?;
}
self.duplex.squeeze(layouter.namespace(|| "squeeze"))
self.sponge
.finish_absorbing(layouter.namespace(|| "finish absorbing"))?
.squeeze(layouter.namespace(|| "squeeze"))
}
}

4
src/circuit/gadget/poseidon/pow5.rs
View File

@ -8,7 +8,7 @@ use halo2::{
poly::Rotation,
};
use super::{PoseidonDuplexInstructions, PoseidonInstructions};
use super::{PoseidonInstructions, PoseidonSpongeInstructions};
use crate::circuit::gadget::utilities::Var;
use crate::primitives::poseidon::{Domain, Mds, Spec, SpongeRate, State};
@ -269,7 +269,7 @@ impl<F: FieldExt, S: Spec<F, WIDTH, RATE>, const WIDTH: usize, const RATE: usize
}
impl<F: FieldExt, S: Spec<F, WIDTH, RATE>, const WIDTH: usize, const RATE: usize>
PoseidonDuplexInstructions<F, S, WIDTH, RATE> for Pow5Chip<F, WIDTH, RATE>
PoseidonSpongeInstructions<F, S, WIDTH, RATE> for Pow5Chip<F, WIDTH, RATE>
{
fn initial_state(
&self,

168
src/primitives/poseidon.rs
View File

@ -24,7 +24,7 @@ use grain::SboxType;
/// The type used to hold permutation state.
pub(crate) type State<F, const T: usize> = [F; T];
/// The type used to hold duplex sponge state.
/// The type used to hold sponge rate.
pub(crate) type SpongeRate<F, const RATE: usize> = [Option<F>; RATE];
/// The type used to hold the MDS matrix and its inverse.
@ -124,7 +124,7 @@ pub(crate) fn permute<F: FieldExt, S: Spec<F, T, RATE>, const T: usize, const RA
});
}
fn poseidon_duplex<F: FieldExt, S: Spec<F, T, RATE>, const T: usize, const RATE: usize>(
fn poseidon_sponge<F: FieldExt, S: Spec<F, T, RATE>, const T: usize, const RATE: usize>(
state: &mut State<F, T>,
input: &SpongeRate<F, RATE>,
pad_and_add: &dyn Fn(&mut State<F, T>, &SpongeRate<F, RATE>),
@ -142,48 +142,65 @@ fn poseidon_duplex<F: FieldExt, S: Spec<F, T, RATE>, const T: usize, const RATE:
output
}
#[derive(Debug)]
pub(crate) enum Sponge<F, const RATE: usize> {
Absorbing(SpongeRate<F, RATE>),
Squeezing(SpongeRate<F, RATE>),
}
/// The state of the [`Sponge`].
// TODO: Seal this trait?
pub trait SpongeMode {}
impl<F: fmt::Debug, const RATE: usize> Sponge<F, RATE> {
pub(crate) fn absorb(val: F) -> Self {
let mut input: [Option<F>; RATE] = (0..RATE)
.map(|_| None)
.collect::<Vec<_>>()
.try_into()
.unwrap();
input[0] = Some(val);
Sponge::Absorbing(input)
/// The absorbing state of the [`Sponge`].
#[derive(Debug)]
pub struct Absorbing<F, const RATE: usize>(pub(crate) SpongeRate<F, RATE>);
/// The squeezing state of the [`Sponge`].
#[derive(Debug)]
pub struct Squeezing<F, const RATE: usize>(pub(crate) SpongeRate<F, RATE>);
impl<F, const RATE: usize> SpongeMode for Absorbing<F, RATE> {}
impl<F, const RATE: usize> SpongeMode for Squeezing<F, RATE> {}
impl<F: fmt::Debug, const RATE: usize> Absorbing<F, RATE> {
pub(crate) fn init_with(val: F) -> Self {
Self(
iter::once(Some(val))
.chain((1..RATE).map(|_| None))
.collect::<Vec<_>>()
.try_into()
.unwrap(),
)
}
}
/// A Poseidon duplex sponge.
pub(crate) struct Duplex<F: FieldExt, S: Spec<F, T, RATE>, const T: usize, const RATE: usize> {
sponge: Sponge<F, RATE>,
/// A Poseidon sponge.
pub(crate) struct Sponge<
F: FieldExt,
S: Spec<F, T, RATE>,
M: SpongeMode,
const T: usize,
const RATE: usize,
> {
mode: M,
state: State<F, T>,
pad_and_add: Box<dyn Fn(&mut State<F, T>, &SpongeRate<F, RATE>)>,
mds_matrix: Mds<F, T>,
round_constants: Vec<[F; T]>,
_marker: PhantomData<S>,
_marker: PhantomData<(S, M)>,
}
impl<F: FieldExt, S: Spec<F, T, RATE>, const T: usize, const RATE: usize> Duplex<F, S, T, RATE> {
/// Constructs a new duplex sponge for the given Poseidon specification.
impl<F: FieldExt, S: Spec<F, T, RATE>, const T: usize, const RATE: usize>
Sponge<F, S, Absorbing<F, RATE>, T, RATE>
{
/// Constructs a new sponge for the given Poseidon specification.
pub(crate) fn new(
initial_capacity_element: F,
pad_and_add: Box<dyn Fn(&mut State<F, T>, &SpongeRate<F, RATE>)>,
) -> Self {
let (round_constants, mds_matrix, _) = S::constants();
let input = [None; RATE];
let mode = Absorbing([None; RATE]);
let mut state = [F::zero(); T];
state[RATE] = initial_capacity_element;
Duplex {
sponge: Sponge::Absorbing(input),
Sponge {
mode,
state,
pad_and_add,
mds_matrix,
@ -194,56 +211,65 @@ impl<F: FieldExt, S: Spec<F, T, RATE>, const T: usize, const RATE: usize> Duplex
/// Absorbs an element into the sponge.
pub(crate) fn absorb(&mut self, value: F) {
match self.sponge {
Sponge::Absorbing(ref mut input) => {
for entry in input.iter_mut() {
if entry.is_none() {
*entry = Some(value);
return;
}
}
// We've already absorbed as many elements as we can
let _ = poseidon_duplex::<F, S, T, RATE>(
&mut self.state,
input,
&self.pad_and_add,
&self.mds_matrix,
&self.round_constants,
);
self.sponge = Sponge::absorb(value);
}
Sponge::Squeezing(_) => {
// Drop the remaining output elements
self.sponge = Sponge::absorb(value);
for entry in self.mode.0.iter_mut() {
if entry.is_none() {
*entry = Some(value);
return;
}
}
// We've already absorbed as many elements as we can
let _ = poseidon_sponge::<F, S, T, RATE>(
&mut self.state,
&self.mode.0,
&self.pad_and_add,
&self.mds_matrix,
&self.round_constants,
);
self.mode = Absorbing::init_with(value);
}
/// Transitions the sponge into its squeezing state.
pub(crate) fn finish_absorbing(mut self) -> Sponge<F, S, Squeezing<F, RATE>, T, RATE> {
let mode = Squeezing(poseidon_sponge::<F, S, T, RATE>(
&mut self.state,
&self.mode.0,
&self.pad_and_add,
&self.mds_matrix,
&self.round_constants,
));
Sponge {
mode,
state: self.state,
pad_and_add: self.pad_and_add,
mds_matrix: self.mds_matrix,
round_constants: self.round_constants,
_marker: PhantomData::default(),
}
}
}
impl<F: FieldExt, S: Spec<F, T, RATE>, const T: usize, const RATE: usize>
Sponge<F, S, Squeezing<F, RATE>, T, RATE>
{
/// Squeezes an element from the sponge.
pub(crate) fn squeeze(&mut self) -> F {
loop {
match self.sponge {
Sponge::Absorbing(ref input) => {
self.sponge = Sponge::Squeezing(poseidon_duplex::<F, S, T, RATE>(
&mut self.state,
input,
&self.pad_and_add,
&self.mds_matrix,
&self.round_constants,
));
}
Sponge::Squeezing(ref mut output) => {
for entry in output.iter_mut() {
if let Some(e) = entry.take() {
return e;
}
}
// We've already squeezed out all available elements
self.sponge = Sponge::Absorbing([None; RATE]);
for entry in self.mode.0.iter_mut() {
if let Some(e) = entry.take() {
return e;
}
}
// We've already squeezed out all available elements
self.mode = Squeezing(poseidon_sponge::<F, S, T, RATE>(
&mut self.state,
&self.mode.0,
&self.pad_and_add,
&self.mds_matrix,
&self.round_constants,
));
}
}
}
@ -301,7 +327,7 @@ impl<F: FieldExt, const T: usize, const RATE: usize, const L: usize> Domain<F, T
}
}
/// A Poseidon hash function, built around a duplex sponge.
/// A Poseidon hash function, built around a sponge.
pub struct Hash<
F: FieldExt,
S: Spec<F, T, RATE>,
@ -309,7 +335,7 @@ pub struct Hash<
const T: usize,
const RATE: usize,
> {
duplex: Duplex<F, S, T, RATE>,
sponge: Sponge<F, S, Absorbing<F, RATE>, T, RATE>,
domain: D,
}
@ -343,7 +369,7 @@ impl<
/// Initializes a new hasher.
pub fn init(domain: D) -> Self {
Hash {
duplex: Duplex::new(domain.initial_capacity_element(), domain.pad_and_add()),
sponge: Sponge::new(domain.initial_capacity_element(), domain.pad_and_add()),
domain,
}
}
@ -355,9 +381,9 @@ impl<F: FieldExt, S: Spec<F, T, RATE>, const T: usize, const RATE: usize, const
/// Hashes the given input.
pub fn hash(mut self, message: [F; L]) -> F {
for value in array::IntoIter::new(message) {
self.duplex.absorb(value);
self.sponge.absorb(value);
}
self.duplex.squeeze()
self.sponge.finish_absorbing().squeeze()
}
}