SNARK-friendly STM: New Key Registration

[curiecrypt]

Content

This PR includes new key registration functionality.
New key registration supports registering different types of keys specific to proof system.
Changing the key registration results in some important modifications in the other (sub-)modules in STM library.

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

This branch provides the STM library to be fully convenient for integrating SNARK proofs.

Issue(s)

Closes #2791

[github-actions]

Test Results

    5 files  ± 0    172 suites  ±0   31m 59s ⏱️ + 1m 3s
2 426 tests + 5  2 426 ✅ + 5  0 💤 ±0  0 ❌ ±0 
7 553 runs  +20  7 553 ✅ +20  0 💤 ±0  0 ❌ ±0 

Results for commit 609870e. ± Comparison against base commit 3fdf7b5.

This pull request removes 3 and adds 8 tests. Note that renamed tests count towards both.

mithril-stm ‑ protocol::aggregate_signature::clerk::tests::test_dedup
mithril-stm ‑ protocol::key_registration::tests::golden::golden_conversions
mithril-stm ‑ protocol::key_registration::tests::test_keyreg

mithril-stm ‑ proof_system::concatenation::aggregate_key::tests::golden::golden_conversions
mithril-stm ‑ proof_system::concatenation::aggregate_key::tests::golden_json::golden_conversions
mithril-stm ‑ proof_system::concatenation::clerk::tests::test_dedup
mithril-stm ‑ protocol::aggregate_signature::aggregate_key::tests::golden_json::golden_conversions
mithril-stm ‑ protocol::key_registration::register::tests::golden::golden_conversions
mithril-stm ‑ protocol::key_registration::register::tests::test_keyreg
mithril-stm ‑ protocol::key_registration::registration_entry::tests::test_ord_different_stakes
mithril-stm ‑ protocol::key_registration::registration_entry::tests::test_ord_same_stake_different_keys

♻️ This comment has been updated with latest results.

[curiecrypt]

@jpraynaud tests related to hex encodings for AggregateVerificationKey fail:

• restorations_from_json_hex_and_bytes_hex_give_same_certificate
• genesis_certificate::restorations_from_bytes_hex_succeeds
  Couldn't resolve why.
  Json serializations for AggregateVerificationKey work. (Golden string matches with the one produced by main implementation) See Golden test for avk #2904

[Copilot]

Pull request overview

This PR implements a significant refactoring of the key registration system in mithril-stm to support SNARK-friendly STM. The changes introduce a new RegistrationEntry type that encapsulates verification keys and stakes, reorganizes the proof system architecture by separating concatenation-specific logic, and updates the API throughout the codebase.

Changes:

• Introduces new RegistrationEntry type and refactors KeyRegistration/ClosedKeyRegistration to use ordered sets
• Restructures proof system by extracting concatenation-specific components (ConcatenationClerk, ConcatenationProofSigner, ConcatenationProofKey)
• Converts AggregateVerificationKey from struct to enum to support multiple proof systems
• Updates all dependent code (tests, examples, benchmarks, mithril-common, mithril-signer, demos) to use new APIs

Reviewed changes

Copilot reviewed 44 out of 44 changed files in this pull request and generated 16 comments.

Show a summary per file

File	Description
mithril-stm/src/protocol/key_registration/registration_entry.rs	New file defining RegistrationEntry with validation and serialization
mithril-stm/src/protocol/key_registration/register.rs	Refactored registration using BTreeSet for ordered entries
mithril-stm/src/protocol/participant/signer.rs	Simplified signer to delegate to proof system-specific signers
mithril-stm/src/protocol/participant/initializer.rs	Updated to create signers with new registration system
mithril-stm/src/proof_system/concatenation/signer.rs	New concatenation proof signer extracted from main Signer
mithril-stm/src/proof_system/concatenation/clerk.rs	New concatenation clerk extracted from main Clerk
mithril-stm/src/proof_system/concatenation/proof_key.rs	New concatenation proof key type
mithril-stm/src/protocol/aggregate_signature/aggregate_key.rs	Converted to enum to support multiple proof systems
mithril-stm/src/protocol/aggregate_signature/clerk.rs	Refactored to delegate to proof-system specific clerks
mithril-stm/src/protocol/error.rs	Added new error variants for registration
mithril-stm/src/lib.rs	Updated type aliases and exports
mithril-stm/tests/*	Updated tests to use new registration API
mithril-stm/examples/*	Updated examples with new API
mithril-stm/benches/*	Updated benchmarks with new API
mithril-common/src/crypto_helper/*	Updated wrappers and type aliases
mithril-signer/src/services/single_signer.rs	Updated to use new Clerk API
demo/protocol-demo/src/*	Updated demo code with new APIs

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[hjeljeli32]

LGTM. I just left a couple of comments.

[damrobi]

Left a few comments on small changes/questions but overall it looks good to me.

[Copilot]

Pull request overview

Copilot reviewed 51 out of 51 changed files in this pull request and generated 3 comments.

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[damrobi]

LGTM, my comments were correctly resolved!

[hjeljeli32]

LGTM.

[jpraynaud]

LGTM 🚀