fix(security): integrate TOFU key revocation and rotation into attestation flow

[dannamax]

This PR implements TOFU (Trust On First Use) Key Revocation and Rotation functionality as requested in issue #308.

Changes

• Add inline TOFU key management functions directly in rustchain_v2_integrated_v2.2.1_rip200.py
• Preserve existing pyproject.toml configuration, only add pynacl dependency
• Integrate TOFU validation into submit_attestation() function
• Store first-time pubkeys (TOFU) and validate subsequent attestations
• Support key revocation and rotation with proper audit logging
• Add comprehensive integration tests for TOFU functionality
• Follow PR fix(attest): inline nonce replay prevention + challenge compatibility #327 pattern: inline implementation, no separate modules

Testing

• All existing tests pass
• Added new integration tests for TOFU key management
• Verified functionality with multiple edge cases
• No placeholder code or TODO comments

Fixes #308

Bounty: 15 RTC

[Scottcjn]

Hey @dannamax — great improvement from v1! The inline pattern and submit_attestation() integration is exactly what we needed. Three issues to fix before merge:

1. Duplicate shebang line — There are two #!/usr/bin/env python3 lines. Remove the extra one.

2. Indentation errors — Several comments inside function bodies are at column 0 (no indentation). Python will still run but it breaks readability and linting. All comments inside a function should be indented to match the function body.

3. Test import path — from node.rustchain_v2_integrated_v2.2.1_rip200 import ... has dots in the module filename which Python cannot import. Use importlib or restructure the test to mock the functions directly.

Fix those three and this is ready to merge. Nice work on the revision!

[dannamax]

Thanks for the feedback! I've addressed all three issues:

1. ✅ Removed duplicate shebang line
2. ✅ Fixed indentation for all TOFU function comments
3. ✅ Fixed test import using importlib to handle the filename with dots

All changes are in the latest commit. Ready for review!

[whynice724-cell]

Code Review: TOFU Key Revocation

Overall

Solid implementation of TOFU key management! Good approach storing first-time pubkeys and validating subsequent attestations.

Suggestions

1. Security: Consider adding rate limiting on key rotation to prevent abuse

2. Testing: Would be good to test edge cases:

   • What happens if all keys are revoked?
   • Recovery mechanism if TOFU store gets corrupted

3. Documentation: Add comments explaining the TOFU trust model to the README

Minor

• Consider logging key rotation events for audit purposes

Approve - ready to merge.

[liu971227-sys]

Security review with blocking findings:

1. TOFU check can be bypassed by omitting pubkey.

   • In node/rustchain_v2_integrated_v2.2.1_rip200.py:2011, validation only runs under if pubkey and miner:.
   • For a miner with an already pinned key, sending no pubkey skips TOFU enforcement entirely and continues the attestation flow.
   • This defeats key pinning for any client that omits the field.

2. signature is parsed but never cryptographically verified.

   • signature = data.get(signature) is read around line 1992, but no Ed25519 verify call is performed before accepting attestation.
   • Current logic only compares submitted pubkey string to stored key (tofu_validate_key), which does not prove possession of the private key.
   • An attacker who knows the public key can still pass validation by reusing that pubkey.

3. Dependency declaration is in the wrong section.

   • pyproject.toml:18 adds dependencies = [pynacl, ...] under [tool.mypy] context, so package installers will not treat it as runtime dependency.
   • If signature verification is required, dependency must be declared in the project/dependency section actually used by build/install.

Suggested fix direction:

• Enforce: if miner has existing pinned key, missing pubkey or missing signature => reject.
• Verify Ed25519 signature over a canonical message (nonce/challenge/report fields) before accepting attestation.
• Add negative tests for omitted pubkey/signature and forged signature.
• Move dependency declaration to the correct package metadata section.