Remove SHA instantiations

Author: b-wagn

README.md

@@ -10,7 +10,7 @@ It was originally developed in [this repository](https://github.com/b-wagn/hash-
 
 The code has *not been audited and is not meant to be used in production*. It is a playground to explore and benchmark these signatures. Use it at your own risk.
 
-The implementation takes a generic RNG as input (e.g., `key_gen`, see below). Users must make sure that the RNG is *cryptographically secure*. 
+The implementation takes a generic RNG as input (e.g., `key_gen`, see below). Users must make sure that the RNG is *cryptographically secure*.
 The examples below, tests, and benchmarks just use a default (potentially insecure) RNG for illustration.
 
 ## Signature Interface
@@ -56,12 +56,11 @@ See also function `test_signature_scheme_correctness` in [this file](https://git
 
 ## Schemes
 The code implements a generic framework from [this paper](https://eprint.iacr.org/2025/055.pdf), which builds XMSS-like hash-based signatures from a primitive called incomparable encodings.
-Hardcoded instantiations of this generic framework (using SHA3 or Poseidon2) are defined in `hashsig::signature::generalized_xmss`.
+Hardcoded instantiations of this generic framework (using Poseidon2) are defined in `hashsig::signature::generalized_xmss`.
 The parameters have been chosen based on the analysis in the paper using Python scripts. Details are as follows:
 
 | Submodule        | Paper / Documentation                                     | Parameters Set With     |
 |---------------|-----------------------------------------------------------|--------------------------|
-| `instantiations_sha::*`        | [original paper](https://eprint.iacr.org/2025/055.pdf)    | [this repository](https://github.com/b-wagn/hashsig-parameters)   |
 | `instantiations_poseidon::*`   | [original paper](https://eprint.iacr.org/2025/055.pdf)    | [this repository](https://github.com/b-wagn/hashsig-parameters)   |
 | `instantiations_poseidon_top_level::*`   | [this document](https://eprint.iacr.org/2025/1332), inspired by [this](https://eprint.iacr.org/2025/889.pdf)  | [this repository](https://github.com/b-wagn/hypercube-hashsig-parameters)   |
 
@@ -97,7 +96,7 @@ cargo bench
 The schemes that are benchmarked are hardcoded instantiations of the generic framework, which are defined in `hashsig::signature::generalized_xmss`.
 The parameters of these instantiations have been chosen carefully with the aim to achieve a desired security level.
 By default, key generation is not benchmarked. There are two options to benchmark it:
-1. add the option `--features with-gen-benches-sha` or `--features with-gen-benches-poseidon` or `--features with-gen-benches-poseidon-top-level` to `cargo bench`. Note that this will make benchmarks very slow, as key generation will be repeated within the benchmarks. Especially for Poseidon, this is not recommended.
+1. add the option `--features with-gen-benches-poseidon` or `--features with-gen-benches-poseidon-top-level` to `cargo bench`. Note that this will make benchmarks very slow, as key generation will be repeated within the benchmarks. Especially for Poseidon, this is not recommended.
 2. use code similar to the one provided in `src/bin/main.rs` and run it with `cargo run --release`.
 
 If criterion only generates json files, one way to extract all means for all benchmarks easily (without re-running criterion) is to run

benches/benchmark.rs

@@ -2,16 +2,13 @@ use criterion::{criterion_group, criterion_main};
 
 mod benchmark_poseidon;
 mod benchmark_poseidon_top_level;
-mod benchmark_sha;
 
 use benchmark_poseidon::bench_function_poseidon;
 use benchmark_poseidon_top_level::bench_function_poseidon_top_level;
-use benchmark_sha::bench_function_sha;
 
 criterion_group!(
     benches,
     bench_function_poseidon_top_level,
-    bench_function_sha,
     bench_function_poseidon
 );
 criterion_main!(benches);

benches/benchmark_sha.rs

@@ -553,96 +553,21 @@ pub mod instantiations_poseidon;
 /// Instantiations of the generalized XMSS signature scheme based on the
 /// top level target sum encoding using Poseidon2
 pub mod instantiations_poseidon_top_level;
-/// Instantiations of the generalized XMSS signature scheme based on SHA
-pub mod instantiations_sha;
 
 #[cfg(test)]
 mod tests {
     use crate::{
-        inc_encoding::{basic_winternitz::WinternitzEncoding, target_sum::TargetSumEncoding},
+        inc_encoding::target_sum::TargetSumEncoding,
         signature::test_templates::test_signature_scheme_correctness,
         symmetric::{
-            message_hash::{
-                MessageHash,
-                poseidon::PoseidonMessageHashW1,
-                sha::{ShaMessageHash, ShaMessageHash192x3},
-            },
-            prf::{sha::ShaPRF, shake_to_field::ShakePRFtoF},
-            tweak_hash::{poseidon::PoseidonTweakW1L5, sha::ShaTweak192192},
+            message_hash::{MessageHash, poseidon::PoseidonMessageHashW1},
+            prf::shake_to_field::ShakePRFtoF,
+            tweak_hash::poseidon::PoseidonTweakW1L5,
         },
     };
 
     use super::*;
 
-    #[test]
-    pub fn test_winternitz() {
-        // Note: do not use these parameters, they are just for testing
-        type PRF = ShaPRF<24, 24>;
-        type TH = ShaTweak192192;
-        type MH = ShaMessageHash192x3;
-        const CHUNK_SIZE: usize = 4;
-        const NUM_CHUNKS_CHECKSUM: usize = 3;
-        type IE = WinternitzEncoding<MH, CHUNK_SIZE, NUM_CHUNKS_CHECKSUM>;
-        const LOG_LIFETIME: usize = 10;
-        type Sig = GeneralizedXMSSSignatureScheme<PRF, IE, TH, LOG_LIFETIME>;
-
-        Sig::internal_consistency_check();
-        test_signature_scheme_correctness::<Sig>(289, 0, Sig::LIFETIME as usize);
-        test_signature_scheme_correctness::<Sig>(2, 0, Sig::LIFETIME as usize);
-        test_signature_scheme_correctness::<Sig>(19, 0, Sig::LIFETIME as usize);
-        test_signature_scheme_correctness::<Sig>(0, 0, Sig::LIFETIME as usize);
-        test_signature_scheme_correctness::<Sig>(11, 0, Sig::LIFETIME as usize);
-    }
-
-    #[test]
-    pub fn test_winternitz_poseidon() {
-        // Note: do not use these parameters, they are just for testing
-        type PRF = ShakePRFtoF<7, 5>;
-        type TH = PoseidonTweakW1L5;
-        type MH = PoseidonMessageHashW1;
-        const CHUNK_SIZE: usize = 1;
-        const _BASE: usize = 2;
-        const NUM_CHUNKS_CHECKSUM: usize = 8;
-        type IE = WinternitzEncoding<MH, CHUNK_SIZE, NUM_CHUNKS_CHECKSUM>;
-        const LOG_LIFETIME: usize = 6;
-        type Sig = GeneralizedXMSSSignatureScheme<PRF, IE, TH, LOG_LIFETIME>;
-
-        Sig::internal_consistency_check();
-
-        test_signature_scheme_correctness::<Sig>(2, 0, Sig::LIFETIME as usize);
-        test_signature_scheme_correctness::<Sig>(19, 0, Sig::LIFETIME as usize);
-        test_signature_scheme_correctness::<Sig>(0, 0, Sig::LIFETIME as usize);
-        test_signature_scheme_correctness::<Sig>(11, 0, Sig::LIFETIME as usize);
-
-        test_signature_scheme_correctness::<Sig>(12, 10, (1 << 5) - 10);
-        test_signature_scheme_correctness::<Sig>(19, 4, 20);
-        test_signature_scheme_correctness::<Sig>(16, 16, 4);
-        test_signature_scheme_correctness::<Sig>(11, 1, 29);
-    }
-
-    #[test]
-    pub fn test_target_sum() {
-        // Note: do not use these parameters, they are just for testing
-        type PRF = ShaPRF<24, 24>;
-        type TH = ShaTweak192192;
-        type MH = ShaMessageHash192x3;
-        const BASE: usize = MH::BASE;
-        const NUM_CHUNKS: usize = MH::DIMENSION;
-        const MAX_CHUNK_VALUE: usize = BASE - 1;
-        const EXPECTED_SUM: usize = NUM_CHUNKS * MAX_CHUNK_VALUE / 2;
-        type IE = TargetSumEncoding<MH, EXPECTED_SUM>;
-        const LOG_LIFETIME: usize = 8;
-        type Sig = GeneralizedXMSSSignatureScheme<PRF, IE, TH, LOG_LIFETIME>;
-
-        Sig::internal_consistency_check();
-
-        test_signature_scheme_correctness::<Sig>(13, 0, Sig::LIFETIME as usize);
-        test_signature_scheme_correctness::<Sig>(9, 0, Sig::LIFETIME as usize);
-        test_signature_scheme_correctness::<Sig>(21, 0, Sig::LIFETIME as usize);
-        test_signature_scheme_correctness::<Sig>(0, 0, Sig::LIFETIME as usize);
-        test_signature_scheme_correctness::<Sig>(31, 0, Sig::LIFETIME as usize);
-    }
-
     #[test]
     pub fn test_target_sum_poseidon() {
         // Note: do not use these parameters, they are just for testing
@@ -707,7 +632,7 @@ mod tests {
         assert_eq!(rho1, rho2);
     }
 
-    #[test]
+    /*#[test]
     pub fn test_large_base_sha() {
         // Note: do not use these parameters, they are just for testing
         type PRF = ShaPRF<24, 8>;
@@ -743,7 +668,7 @@ mod tests {
 
         test_signature_scheme_correctness::<Sig>(2, 0, Sig::LIFETIME as usize);
         test_signature_scheme_correctness::<Sig>(19, 0, Sig::LIFETIME as usize);
-    }
+    }*/
 
     #[test]
     pub fn test_expand_activation_time() {