Tore/chore/2813/additional backwards compatibility

[jot2re]

Description of changes

• Removes the usage of bc2wrap` serialization for elements in MPC contexts.
• Increases values used in versioning.

Issue ticket number and link

This closes https://github.com/zama-ai/kms-internal/issues/2813

PR Checklist

I attest that all checked items are satisfied. Any deviation is clearly justified above.

• Title follows conventional commits (e.g. chore: ...).
• Tests added for every new pub item and test coverage has not decreased.
• Public APIs and non-obvious logic documented; unfinished work marked as TODO(#issue).
• unwrap/expect/panic only in tests or for invariant bugs (documented if present).
• No dependency version changes OR (if changed) only minimal required fixes.
• No architectural protocol changes OR linked spec PR/issue provided.
• No breaking deployment config changes OR devops label + infra notified + infra-team reviewer assigned.
• No breaking gRPC / serialized data changes OR commit marked with ! and affected teams notified.
• No modifications to existing versionized structs OR backward compatibility tests updated.
• No critical business logic / crypto changes OR ≥2 reviewers assigned.
• No new sensitive data fields added OR Zeroize + ZeroizeOnDrop implemented.
• No new public storage data OR data is verifiable (signature / digest).
• No unsafe; if unavoidable: minimal, justified, documented, and test/fuzz covered.
• Strongly typed boundaries: typed inputs validated at the edge; no untyped values or errors cross modules.
• Self-review completed.

Dependency Update Questionnaire (only if deps changed or added)

Answer in the Cargo.toml next to the dependency (or here if updating):

1. Ownership changes or suspicious concentration?
2. Low popularity?
3. Unusual version jump?
4. Lacking documentation?
5. Missing CI?
6. No security / disclosure policy?
7. Significant size increase?

More details and explanations for the checklist and dependency updates can be found in CONTRIBUTING.md

[github-actions]

Consolidated Tests Results 2025-12-01 - 20:07:41

Test Results

4 passed

Details

4 tests
not captured
junit-to-ctrf
kind-testing test-reporter #191
Tore/chore/2813/additional backwards compatibility #298

test-reporter: Run #191

Tests 📝	Passed ✅	Failed ❌	Skipped ⏭️	Pending ⏳	Other ❓	Flaky 🍂	Duration ⏱️
4	4	0	0	0	0	0	not captured

🎉 All tests passed!

Tests

View All Tests

Test Name	Status	Flaky	Duration
full_gen_tests_default_threshld_sequential_crs	✅		2m 23s
test_threshld_insecure	✅		3m 21s
full_gen_tests_default_centralzd_sequential_crs	✅		1.8s
test_centralzd_insecure	✅		1m 1s

_{🍂 No flaky tests in this run.}

Github Test Reporter by CTRF 💚

🔄 This comment has been updated