chore(rust): upgrade ed25519-dalek 2.x -> 3.x and rand 0.8 -> 0.10 (fixes #3355)

[AlgoVoi (Christopher Hopley) (chopmob-cloud)]

Summary

Upgrades ed25519-dalek 2.2.0 -> 3.0.0 and rand 0.8.6 -> 0.10.2 across the agent-governance-rust workspace, as requested in #3355.

Dependabot #3269 (dalek 3) and #3271 (rand 0.10) each failed build-rust because they bump one crate at a time. The two must move together: ed25519-dalek 3 rides rand_core 0.9, which rand 0.10 provides, so bumping either alone leaves a rand_core version mismatch. This is a single coordinated PR.

What actually changed

Bumping both together showed that the ed25519-dalek 2 -> 3 signing/verifying surface used in this crate is source-compatible (SigningKey::generate, Signature::from_bytes, VerifyingKey::from_bytes, Signer/Verifier). All the real edits are the rand 0.9/0.10 trait and module reshuffle:

• rand::distributions -> rand::distr (clock.rs)
• rand::thread_rng() -> rand::rng() in non-key-material paths (clock.rs, the AES-GCM nonce in credential_vault.rs)
• the old Rng extension trait (providing sample_iter) is now RngExt (clock.rs)
• the old RngCore core trait (providing fill_bytes) is now named Rng (credential_vault.rs)
• rand::rngs::OsRng was removed; key generation now uses UnwrapErr(SysRng) (identity.rs, identity_support.rs, credential_vault.rs), see below

Note on key-generation RNG

SigningKey::generate in ed25519-dalek 3 requires an infallible CryptoRng (pub fn generate<R: CryptoRng + ?Sized>(csprng: &mut R)). The documented pattern in the ed25519-dalek 3.0.0 SigningKey::generate docs is OS entropy through the UnwrapErr adapter: let mut csprng = UnwrapErr(SysRng); SigningKey::generate(&mut csprng). SysRng (the getrandom 0.4 system source re-exported by rand 0.10 as rand::rngs::SysRng) implements the fallible TryCryptoRng, and rand_core's UnwrapErr wrapper turns it into an infallible CryptoRng via the blanket impl, satisfying the bound directly from OS entropy with no new dependency and no lockfile change.

Every key-material path draws from UnwrapErr(SysRng): AgentIdentity::generate/delegate, Credential::issue, KeyRotationManager::rotate, and the vault's AES-256-GCM CredentialVault::generate_key. Thread RNG (rand::rng()) remains only where key material is not involved (the AES-GCM nonce, generated identifiers, the attestation challenge nonce, and the MCP clock nonce). This draws long-lived key material straight from the OS CSPRNG and removes the thread-local reseed and fork-safety caveats from the keygen path. The dependency-audit doc records the split.

Validation

agent-governance-rust, from a green baseline:

	baseline (2.2.0 / 0.8.6)	this PR (3.0.0 / 0.10.2)
cargo build --workspace	clean	clean, no new warnings
cargo test --workspace --locked	514 pass, 0 fail	518 pass, 0 fail (Linux)
cargo clippy --workspace --all-targets	9 warnings	9 warnings (0 new)

The PR adds two keygen tests (distinct usable keys with cross-verification rejection; distinct non-zero vault keys), which is the +4 delta over the 514 baseline together with the branch's earlier additions. The suite still includes the signature-rejection tests (trust::test_verify_peer_rejects_mismatched_claimed_peer, trust::test_verify_peer_rejects_signature_not_created_by_peer, mcp::signing::tests::rejects_replayed_messages), so verification still refuses forged and replayed signatures, not merely accepts valid ones.

Fixes #3355.

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[github-actions]

🤖 AI Agent: code-reviewer — View details

AI-generated review output. Treat it as untrusted analysis and verify before acting.

TL;DR: 0 blockers, 0 warnings. Safe and clean upgrade.

#	Sev	Issue	Where

No issues found. Clean change.

[github-actions]

🤖 AI Agent: contributor-guide — View details

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Welcome, and thank you for your contribution! Great job coordinating the ed25519-dalek and rand upgrades to resolve dependency conflicts effectively.

Before we can merge, please address the following:

1. Ensure that all removed dependencies in Cargo.lock are no longer required by any part of the project.
2. Verify that the changes to rand usage (e.g., rand::rng() and RngExt) are consistent across all affected files.

For more details, refer to our CONTRIBUTING.md. Let us know if you need any help!

[github-actions]

🤖 AI Agent: docs-sync-checker — Docs Sync

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Docs Sync

• README.md -- no updates found for the changes in the pull request.
• CHANGELOG.md -- missing entry for the upgrade of ed25519-dalek and rand versions, as well as the associated behavioral changes (e.g., OsRng to rand::rng() for key generation).

Please ensure the CHANGELOG.md reflects these updates.

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🤖 AI Agent: security-scanner — View details

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No security issues found.

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Test coverage looks good. No gaps identified.

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🤖 AI Agent: breaking-change-detector — API Compatibility

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API Compatibility

Severity	Change	Impact
High	Upgrade ed25519-dalek from 2.x to 3.x	Potential breaking change due to major version bump. While the PR notes that the signing/verifying surface is source-compatible, downstream consumers relying on internal or undocumented behavior may face issues.
High	Upgrade rand from 0.8 to 0.10	Potential breaking change due to major version bump. Changes in trait and module structure (e.g., rand::distributions → rand::distr, OsRng replaced with ThreadRng) may impact consumers relying on the previous API.
Medium	Replacement of rand::rngs::OsRng with rand::rng()	May affect users who explicitly depend on OsRng for cryptographic random number generation.

[github-actions]

PR Review Summary

Check	Status	Details
🔍 Code Review	⚠️ Missing	No current-run comment
🛡️ Security Scan	⚠️ Missing	No current-run comment
🔄 Breaking Changes	⚠️ Missing	No current-run comment
📝 Docs Sync	⚠️ Missing	No current-run comment
🧪 Test Coverage	⚠️ Missing	No current-run comment

Verdict: ⚠️ AI review incomplete; ready for human review

AI review comments are untrusted advisory output. The summary reports workflow-generated completion status only, not model-authored pass/fail claims.

[github-actions]

🔴 Contributor Check: HIGH

Check	Result
Profile	HIGH
Credential	LOW
Overall	HIGH

Automated check by AGT Contributor Check.

[Copilot]

Pull request overview

TL;DR: 0 blockers, 0 warnings. No issues found. Clean change.

Changes:

• Upgrade ed25519-dalek from 2.2.0 to 3.0.0 and rand from 0.8.6 to 0.10.2 across the agent-governance-rust workspace.
• Update call sites for rand 0.10 API moves/renames (e.g., distributions → distr, thread_rng() → rng(), Rng → RngExt, RngCore → Rng).

Reviewed changes

Copilot reviewed 5 out of 6 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
agent-governance-rust/Cargo.toml	Pins ed25519-dalek to =3.0.0 and rand to =0.10.2 at the workspace level.
agent-governance-rust/Cargo.lock	Updates the resolved dependency graph for the coordinated ed25519-dalek/rand upgrade.
agent-governance-rust/agentmesh/src/identity.rs	Switches key generation RNG call from OsRng to rand::rng() for SigningKey::generate.
agent-governance-rust/agentmesh/src/identity_support.rs	Updates SigningKey::generate RNG call sites to rand::rng() for credential/key rotation paths.
agent-governance-rust/agentmesh/src/credential_vault.rs	Adapts RNG trait usage (RngCore → Rng) and updates thread_rng() → rng() for byte filling.
agent-governance-rust/agentmesh-mcp/src/mcp/clock.rs	Updates rand imports (distr, RngExt) and RNG creation (rng()) for nonce generation.

[Imran Siddique (imran-siddique)]

MohammadHaroonAbuomar this is the closest Rust PR to merge: mergeable, CI clean, resolves #3355, and the duplicate #3418 is now closed. Could you give it a code-owner review when you have a moment? Thanks.

[Copilot]

Pull request overview

Copilot reviewed 6 out of 7 changed files in this pull request and generated no new comments.

[Copilot]

Pull request overview

Copilot reviewed 7 out of 8 changed files in this pull request and generated no new comments.

[MohammadHaroonAbuomar]

• Process: real CI has never run on this head (all green checks are pull_request_target bot jobs; build-rust/CodeQL/SBOM stuck action_required) and the PR is CONFLICTING on the exact Cargo.toml/lock block being upgraded. Rebase onto main, get workflow runs approved, require genuinely green CI. (Local compensating run at head: cargo test 514/514 pass; code content verified sound incl. dalek3 signing determinism and no seeded-RNG leaks.)

Minor:

• audit doc omission: OsRng->ThreadRng is not strictly equivalent (thread-local ChaCha12, reseeds per 64KiB, not fork-safe; no fork usage in workspace today). Add a line.

[MohammadHaroonAbuomar]

• Process: real CI has never run on this head (all green checks are pull_request_target bot jobs; build-rust/CodeQL/SBOM stuck action_required) and the PR is CONFLICTING on the exact Cargo.toml/lock block being upgraded. Rebase onto main, get workflow runs approved, require genuinely green CI. (Local compensating run at head: cargo test 514/514 pass; code content verified sound incl. dalek3 signing determinism and no seeded-RNG leaks.)

Minor:

• audit doc omission: OsRng->ThreadRng is not strictly equivalent (thread-local ChaCha12, reseeds per 64KiB, not fork-safe; no fork usage in workspace today). Add a line.

[AlgoVoi (Christopher Hopley) (chopmob-cloud)]

Thanks for the review. Rebased onto the current upstream/main (8f7a4c9, 15 commits ahead of the previous base). The rebase applied cleanly with zero conflicts: none of the new main commits touch agent-governance-rust, and GitHub now reports the PR mergeable, so the earlier Cargo.toml/Cargo.lock conflict is resolved.

Local validation on the rebased head: cargo test --workspace --locked passes with 0 failures on both a Linux gnu toolchain (516 passed) and a Windows gnu toolchain (515 passed; the one-test delta is a target-gated case, not a failure). This includes the forgery and replay rejection tests (trust::test_verify_peer_rejects_mismatched_claimed_peer, trust::test_verify_peer_rejects_signature_not_created_by_peer, mcp::signing::tests::rejects_replayed_messages), which I re-ran by name to confirm they execute rather than filter out. The --locked flag confirms the lockfile is fully consistent (ed25519-dalek 3.0.0, rand 0.10.2, single rand_core 0.10.1, no git dependencies).

Both minor items from your review are in the audit doc: the OsRng to ThreadRng non-equivalence note (thread-local ChaCha12, per-64KiB reseed, not fork-safe, with the caveat that nothing in the workspace forks today) and the corrected getrandom table (0.2.17 + 0.3.4 + 0.4.3 after, matching the lockfile).

The remaining gate is on the maintainer side: build-rust, CodeQL, and SBOM sit at action_required until a maintainer approves workflow runs for this fork head. Once approved, real CI will run against the rebased head.

[Copilot]

Pull request overview

Copilot reviewed 7 out of 8 changed files in this pull request and generated no new comments.

[AlgoVoi (Christopher Hopley) (chopmob-cloud)]

One further hardening since the last update: key generation no longer uses rand's thread RNG. All five key-material call sites (the four Ed25519 SigningKey::generate sites and the vault's AES-256-GCM generate_key) now draw OS entropy via UnwrapErr(SysRng), which is the pattern the ed25519-dalek 3.0.0 SigningKey::generate documentation shows. This removes the thread-local ChaCha12 state, the per-64 KiB reseed window, and the fork-safety caveat from the keygen path, with no new dependency and no lockfile change. Thread rng survives only in non-key-material spots (nonces and generated ids), and the audit doc now lists them explicitly. Two tests were added: distinct usable keys with cross-verification rejection, and distinct non-zero vault keys. Full workspace suite is 518 pass, 0 fail on Linux, including the forgery and replay rejection tests.

[Copilot]

Pull request overview

Copilot reviewed 8 out of 9 changed files in this pull request and generated no new comments.

Suppressed comments (1)

docs/dependency-audits/2026-07-27-ed25519-dalek-3-rand-0.10.md:110

• The verification paragraph claims "514 tests passing" and "identical to the pre-upgrade baseline", but this PR adds new keygen tests (and the PR description reports a higher test count). To avoid leaving an incorrect audit record, update this section to avoid hard-coded counts (or update them to the actual current totals).

Verification: `cargo build`, `cargo test` and `cargo clippy` are green, with
514 tests passing, identical to the pre-upgrade baseline, with no tests
skipped or removed.

[Copilot]

Pull request overview

Copilot reviewed 8 out of 9 changed files in this pull request and generated no new comments.

[Copilot]

Pull request overview

Copilot reviewed 8 out of 9 changed files in this pull request and generated no new comments.

Suppressed comments (4)

agent-governance-rust/agentmesh/src/identity.rs:83

• Same issue as above: SigningKey::generate(&mut UnwrapErr(SysRng)) borrows a temporary UnwrapErr(SysRng) as &mut, which is not allowed in this call form. Use a local mut binding for the RNG adapter.

        let signing_key = SigningKey::generate(&mut UnwrapErr(SysRng));
        let public_key = signing_key.verifying_key();

agent-governance-rust/agentmesh/src/identity_support.rs:1058

• SigningKey::generate(&mut UnwrapErr(SysRng)) borrows a temporary RNG adapter as &mut and is likely to fail to compile. Introduce a local mut csprng binding and pass &mut csprng.

            });
        let signing_key = SigningKey::generate(&mut UnwrapErr(SysRng));
        let public_key = signing_key.verifying_key();

agent-governance-rust/agentmesh/src/identity.rs:34

• SigningKey::generate(&mut UnwrapErr(SysRng)) takes a mutable reference to a temporary UnwrapErr(SysRng) value; Rust does not allow borrowing a temporary as &mut in a function call, so this is likely to fail to compile. Bind the RNG adapter to a local mut variable first, then pass &mut to that.

This issue also appears on line 82 of the same file.

        // OS entropy per the ed25519-dalek 3 documented pattern for key generation.
        let signing_key = SigningKey::generate(&mut UnwrapErr(SysRng));
        let public_key = signing_key.verifying_key();

agent-governance-rust/agentmesh/src/identity_support.rs:175

• SigningKey::generate(&mut UnwrapErr(SysRng)) attempts to take &mut to a temporary UnwrapErr(SysRng) value; this pattern is likely to fail to compile. Bind UnwrapErr(SysRng) to a local mut variable first.

This issue also appears on line 1056 of the same file.

        let expires_at_secs = issued_at_secs.saturating_add(ttl_seconds.max(1));
        // OS entropy per the ed25519-dalek 3 documented pattern for key generation.
        let signing_key = SigningKey::generate(&mut UnwrapErr(SysRng));
        let token = URL_SAFE_NO_PAD.encode(signing_key.to_bytes());

[Prayag (prayagupa)]

Correct ed25519-dalek 2→3 / rand 0.8→0.10 migration — OsRng → UnwrapErr(SysRng), thread_rng() → rng(), distributions → distr/RngExt — with added tests asserting distinct, verifiable OS-entropy keys. Test Coverage, Security Scan, and Breaking Changes are all green. LGTM.

[AlgoVoi (Christopher Hopley) (chopmob-cloud)]

@MohammadHaroonAbuomar following up on imran-siddique's ping from a couple of weeks ago. The PR is rebased onto current main (as of 2026-08-04), all CI checks are green, and GitHub reports it mergeable. Happy to address any questions if something is holding up the review.

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