Reduce hades constants from 960 to 335

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Changed
+
+- Reduce hades constants count in circuit compression from 960 to 335 [#813]
+
 ## [0.19.0] - 2024-01-03
 
 ### Fixed
@@ -563,6 +567,7 @@ is necessary since `rkyv/validation` was required as a bound.
 - Proof system module.
 
 <!-- ISSUES -->
+[#813]: https://github.com/dusk-network/plonk/issues/813
 [#805]: https://github.com/dusk-network/plonk/issues/805
 [#804]: https://github.com/dusk-network/plonk/issues/804
 [#802]: https://github.com/dusk-network/plonk/issues/802

rust-toolchain.toml

@@ -1,3 +1,3 @@
 [toolchain]
-channel = "nightly-2023-05-24"
-components = ["rustfmt", "clippy"]
+channel = "nightly-2023-11-10"
+components = ["rustfmt", "clippy"]

src/composer/compress/hades.rs

@@ -4,14 +4,18 @@
 //
 // Copyright (c) DUSK NETWORK. All rights reserved.
 
-use sha2::{Digest, Sha512};
+// Extracted from
+// https://github.com/dusk-network/Poseidon252/blob/master/assets/HOWTO.md
 
 use super::BlsScalar;
+use sha2::{Digest, Sha512};
 
-const CONSTANTS: usize = 960;
-
-// Extracted from
-// https://github.com/dusk-network/Hades252/blob/a4d55e06ee9ff7f549043582e8d194eb0a01bf24/assets/HOWTO.md
+// the width of the hades permutation container
+const WIDTH: usize = 5;
+// the total amount of rounds (partial + full) within one hades permutation
+const ROUNDS: usize = 59 + 8;
+// the amount of constants needed for one hades permutation
+const CONSTANTS: usize = ROUNDS * WIDTH;
 
 pub fn constants() -> [BlsScalar; CONSTANTS] {
     let mut cnst = [BlsScalar::zero(); CONSTANTS];
@@ -31,8 +35,6 @@ pub fn constants() -> [BlsScalar; CONSTANTS] {
     cnst
 }
 
-const WIDTH: usize = 5;
-
 pub fn mds() -> [[BlsScalar; WIDTH]; WIDTH] {
     let mut matrix = [[BlsScalar::zero(); WIDTH]; WIDTH];
     let mut xs = [BlsScalar::zero(); WIDTH];