refactor(stm): harden legacy decoders and key registration

[damrobi]

Content

This PR includes some updates of legacy decoders and of the key registration. The updates harden the robustness of the decoders and of the key registration.

Changes

• KeyRegistration now keeps two HashMap to keep track of the registered keys

Pre-submit checklist

• Branch
  • Tests are provided (if possible)
  • Crates versions are updated (if relevant)
  • CHANGELOG file is updated (if relevant)
  • Commit sequence broadly makes sense
  • Key commits have useful messages
• PR
  • All check jobs of the CI have succeeded
  • Self-reviewed the diff
  • Useful pull request description
  • Reviewer requested

Comments

Issue(s)

[github-actions]

Test Results

     5 files  ± 0     209 suites  ±0   34m 1s ⏱️ - 2h 41m 5s
 3 315 tests  - 71   3 315 ✅  - 71  0 💤 ±0  0 ❌ ±0 
11 050 runs   - 71  11 050 ✅  - 71  0 💤 ±0  0 ❌ ±0 

Results for commit 7b4d7f8. ± Comparison against base commit 936eadd.

This pull request removes 73 and adds 2 tests. Note that renamed tests count towards both.

mithril-stm ‑ circuits::halo2::tests::golden::cases::negative::slow::index_out_of_bounds
mithril-stm ‑ circuits::halo2::tests::golden::cases::negative::slow::index_too_large_for_circuit_range
mithril-stm ‑ circuits::halo2::tests::golden::cases::negative::slow::indices_not_increasing
mithril-stm ‑ circuits::halo2::tests::golden::cases::negative::slow::leaf_merkle_path_mismatch
mithril-stm ‑ circuits::halo2::tests::golden::cases::negative::slow::leaf_swap_keep_merkle_path
mithril-stm ‑ circuits::halo2::tests::golden::cases::negative::slow::leaf_wrong_verification_key
mithril-stm ‑ circuits::halo2::tests::golden::cases::negative::slow::merkle_path_corrupt_sibling
mithril-stm ‑ circuits::halo2::tests::golden::cases::negative::slow::merkle_path_flip_position
mithril-stm ‑ circuits::halo2::tests::golden::cases::negative::slow::merkle_path_length_long
mithril-stm ‑ circuits::halo2::tests::golden::cases::negative::slow::merkle_path_length_short
…

mithril-stm ‑ protocol::key_registration::register::tests::register_by_entry_rejects_same_snark_key_with_different_concatenation_key
mithril-stm ‑ protocol::key_registration::register::tests::register_by_entry_rejects_same_verification_key_with_different_stake

♻️ This comment has been updated with latest results.

[Copilot]

Pull request overview

This PR hardens mithril-stm’s legacy byte decoders against malformed inputs and strengthens key registration by enforcing uniqueness on verification keys (rather than on full registration entries that include stake).

Changes:

• Hardened legacy from_bytes_legacy deserializers to use checked arithmetic and safe slice access.
• Updated KeyRegistration to track registered verification keys via dedicated maps and reject duplicates even if stake differs.
• Bumped mithril-stm to 0.11.3 and propagated the version update through workspace dependencies and changelog.

Reviewed changes

Copilot reviewed 6 out of 7 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
mithril-stm/src/protocol/key_registration/register.rs	Enforces key-level uniqueness during registration (and adds tests for duplicate-key scenarios).
mithril-stm/src/proof_system/concatenation/aggregate_key.rs	Hardens legacy aggregate key decoding by avoiding unchecked slice indexing.
mithril-stm/src/membership_commitment/merkle_tree/path.rs	Hardens legacy Merkle path/batch path decoding with checked offsets and safe slicing.
mithril-stm/CHANGELOG.md	Adds 0.11.3 entry describing the decoder and key registration hardening.
mithril-stm/Cargo.toml	Bumps crate version to 0.11.3.
mithril-common/Cargo.toml	Updates dependency on mithril-stm to 0.11.3.
Cargo.lock	Updates lockfile for mithril-stm version bump.