From d14bda794506b25a7c4e58a0ad60b2fe89dc352e Mon Sep 17 00:00:00 2001
From: moana <moana@dusk.network>
Date: Tue, 13 Feb 2024 11:17:44 +0100
Subject: [PATCH 1/2] Reduce hades constants from 960 to 335

Resolves #813
---
 CHANGELOG.md                   |  5 +++++
 src/composer/compress/hades.rs | 16 +++++++++-------
 2 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 85f244b8..41f30257 100644
--- a/CHANGELOG.md
+++ b/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
diff --git a/src/composer/compress/hades.rs b/src/composer/compress/hades.rs
index 8b1000cd..c1047caa 100644
--- a/src/composer/compress/hades.rs
+++ b/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];

From cf2dcf363b27c9377bde2a691927cc65750b731f Mon Sep 17 00:00:00 2001
From: moana <moana@dusk.network>
Date: Tue, 13 Feb 2024 11:24:28 +0100
Subject: [PATCH 2/2] Update toolchain to nightly-2023-11-10

---
 rust-toolchain.toml | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/rust-toolchain.toml b/rust-toolchain.toml
index de54b29a..e4ada996 100644
--- a/rust-toolchain.toml
+++ b/rust-toolchain.toml
@@ -1,3 +1,3 @@
 [toolchain]
-channel = "nightly-2023-05-24"
-components = ["rustfmt", "clippy"]
\ No newline at end of file
+channel = "nightly-2023-11-10"
+components = ["rustfmt", "clippy"]