Skip to content

feat: remove cache in static length poseidon2 #28

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
jialinli98 merged 3 commits into from
Jan 14, 2026
Merged

feat: remove cache in static length poseidon2 #28

Changes from all commits
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
d5bd576
remove cache in static length poseidon2
jialinli98 Jan 13, 2026
8c27ee5
Update src/poseidon2.nr
jialinli98 Jan 14, 2026
8e39eb6
simplify
jialinli98 Jan 14, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
31 changes: 26 additions & 5 deletions src/poseidon2.nr
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -62,13 +62,34 @@ impl Poseidon2 {
fn hash_internal<let N: u32>(input: [Field; N], in_len: u32) -> Field {
let two_pow_64 = 18446744073709551616;
let iv: Field = (in_len as Field) * two_pow_64;
let mut sponge = Poseidon2::new(iv);
for i in 0..input.len() {
if i < in_len {
sponge.absorb(input[i]);
let mut state = [0; 4];
state[RATE] = iv;

if std::runtime::is_unconstrained() {
for i in 0..in_len {
state[i % RATE] += input[i];
if (i + 1) % RATE == 0 {
state = crate::poseidon2_permutation(state, 4);
}
}
Comment on lines +69 to +74
Copy link
Member

@TomAFrench TomAFrench Jan 13, 2026

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

This should be done in a followup but I'd like to explore us partially unrolling this so that we writes into the state array 4 at a time to avoid needing to do so many modulos.

Copy link
Member

@TomAFrench TomAFrench Jan 13, 2026

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

See https://github.com/AztecProtocol/aztec-packages/blob/next/noir-projects/noir-protocol-circuits/crates/types/src/hash/poseidon2_chunks.nr

} else {
for i in 0..input.len() {
if i < in_len {
state[i % RATE] += input[i];
if (i + 1) % RATE == 0 {
state = crate::poseidon2_permutation(state, 4);
}
}
}
}
sponge.squeeze()

// Always run final permutation unless we just completed a full chunk
// still need to permute once if in_len is 0
if (in_len == 0) | (in_len % RATE != 0) {
state = crate::poseidon2_permutation(state, 4)
};

state[0]
}
}

Expand Down