pkc%feat!: harmonize tweaks across {Bls,Ecdsa}{Public,Secret}Key, report zero scalar in add_tweak_sk as InvalidSecretKey, fix perf degradation on Drop

[kwvg]

Additional Information

• Microbenchmarks during consumer integration found that Drop performance worsened when using dash-pkc because the public key is rederived for the fixed pattern used to overwrite the contents of the secret key. This was resolved by computing the expected public key in advance and simply copying it instead.

Breaking Changes

Refer to changelog.

How Has This Been Tested?

./contrib/git_filter.py --fast-fail develop tweaky -- bash -c 'cargo clippy --all-targets --no-default-features -- -D warnings && cargo clippy --all-targets --features full -- -D warnings && cargo test --all-targets --features full && ./maint/lint_all.py'

Checklist

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have added or updated relevant unit/integration/functional tests
• I have made corresponding changes to the documentation
• I have assigned this pull request to a milestone (for repository code-owners and collaborators only)

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• pkgs/pkc/src/bls/secret_ops.rs

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📝 Walkthrough

Walkthrough

BLS and ECDSA key types gain tweak multiplication and negation operations. Tests cover operation results and invalid inputs. ECDSA secret-key negation now returns a new key, and zeroization uses an erased-point constant with a fallback derivation.

Changes

BLS and ECDSA key operations

Layer / File(s)	Summary
BLS tweak and negate operations pkgs/pkc/src/bls/scheme_ops.rs, pkgs/pkc/src/bls/tests.rs, pkgs/pkc/src/bls/public_ops.rs, pkgs/pkc/src/bls/secret_ops.rs, pkgs/pkc/src/bls/scheme_chia.rs	BLS scheme operations and key wrappers add secret-key tweak multiplication and secret- and public-key negation. Tests cover agreement, operation properties, and rejection of invalid inputs for both schemes.
ECDSA tweak, negate, and zeroization changes pkgs/pkc/src/ecdsa/curve_consts.rs, pkgs/pkc/src/ecdsa/public_ops.rs, pkgs/pkc/src/ecdsa/secret_ops.rs, pkgs/pkc/src/ecdsa/tests.rs	ECDSA key types add tweak multiplication and public-key negation. Secret-key negation now returns a new key. Zeroization uses the erased-point constant with a derivation fallback. Tests cover key agreement, serialization forms, invalid factors, negation, and zeroization.
API and capability records pkgs/pkc/CHANGELOG.md, maint/codeql/rust/pkc.model.yml	The changelog records the added operations and the ECDSA secret-key negation signature change. The CodeQL model removes the ECDSA secret-key negation entry from armOnly and adds EdDSA operation entries to armLacks.

Priority: ➖ Normal

Merge Risk: ⚪ Minimal · up to 74ee8

No concrete in-repository merge risk was established; the ECDSA negation API change is documented, and repository callers use its returned key.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	Docstring coverage is 84.75% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 59 functions across 9 files.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	The title accurately summarizes the key changes: harmonized key tweaks, zero-scalar error handling, and improved Drop performance. It is long but specific and relevant.
Description check	✅ Passed	The description explains the Drop performance fix, identifies breaking changes, and lists validation steps that relate to the changeset.

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Actionable comments posted: 1

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• 🪄 Fix CodeRabbit comments on this PR

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Inline comments:
Review comments at @pkgs/pkc/src/bls/secret_ops.rs:
- Around line 112-119: Update the error documentation on BlsSecretKey::negate to
state that it can return InvalidSecretKey when the inner scalar is zero,
including after the key has been zeroized; remove the claim that it never
returns an error.

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Configuration used: Repository UI

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Run ID: c7b00175-f032-4b18-85fb-b8b3915d4768

📥 Commits

Reviewing files that changed from the base of the PR and between e6402ce and 6c937be.

📒 Files selected for processing (11)

• maint/codeql/rust/pkc.model.yml
• pkgs/pkc/CHANGELOG.md
• pkgs/pkc/src/bls/public_ops.rs
• pkgs/pkc/src/bls/scheme_chia.rs
• pkgs/pkc/src/bls/scheme_ops.rs
• pkgs/pkc/src/bls/secret_ops.rs
• pkgs/pkc/src/bls/tests.rs
• pkgs/pkc/src/ecdsa/curve_consts.rs
• pkgs/pkc/src/ecdsa/public_ops.rs
• pkgs/pkc/src/ecdsa/secret_ops.rs
• pkgs/pkc/src/ecdsa/tests.rs

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