Ballot creation timestamp verification

[Just-Bamford]

Summary

The contract stores ballot creation time but does not verify it matches the backend database. If the contract timestamp diverges from the backend timestamp, voting logic based on time (deadlines, open/closed status) can become inconsistent. The contract should verify that ballots registered on-chain have matching timestamps.

This is a Milestone 2 reliability issue. Timestamp consistency is important for vote validity.

Background

When a ballot is created on the backend, a record is written to the database and simultaneously (or later) to the contract. There is no guarantee the timestamps match. If they diverge, a vote could be accepted by the contract but rejected by the backend, or vice versa, causing confusion and incorrect vote tallies.

Scope

Contract

• When a ballot is created, store the creation timestamp in contract storage
• Add a function verify_ballot_timestamp(ballot_id: String, expected_timestamp: u64): Result<(), Error>
• Function compares the stored timestamp with the expected timestamp
• Returns OK if within a 60-second tolerance
• Returns TIMESTAMP_MISMATCH if they diverge more than 60 seconds
• Logs discrepancy for audit trail

Backend Integration

• After creating a ballot on-chain, call verify_ballot_timestamp with the backend timestamp
• Store the verification result in ballotResults or a new ballotVerification table
• If verification fails, log a warning and alert admins

Tests

• Timestamp verification passes when times match
• Verification fails when times diverge more than 60 seconds
• 60-second tolerance is enforced
• Error message includes the time delta

Relevant Files

• contracts/anonvote/src/lib.rs
• backend/src/services/sorobanService.ts
• backend/prisma/schema.prisma

Acceptance Criteria

• Contract stores and verifies timestamps
• Backend calls verification function
• Results logged and stored
• Tests pass
• Tolerance is documented

Out of Scope

• Automatic timestamp correction — detection only
• Blockchain time synchronization — use system time as-is

Note for Contributors

Use a 60-second tolerance to account for network latency and clock skew between systems. Do not block operations on timestamp mismatch — log it for audit trail and let operations continue. This is for transparency, not enforcement.

[midenotch]

I'd like to work on this issue.

My approach is to implement timestamp verification as an additional reliability layer between the backend and the Soroban contract. I'll update the contract to persist each ballot's creation timestamp and expose a verify_ballot_timestamp function that compares the stored value with the backend timestamp, enforcing the specified 60-second tolerance and returning a clear TIMESTAMP_MISMATCH error when the threshold is exceeded. I'll also ensure discrepancies are logged to support auditing.

On the backend, I'll integrate the verification step immediately after ballot creation, persist the verification result in the appropriate data model, and log or surface warnings for failed verifications so administrators can investigate inconsistencies. I'll also update the relevant schema if a dedicated verification record is required.

Finally, I'll add comprehensive contract and backend tests covering successful verification, tolerance boundary conditions, timestamp mismatches, and error reporting, while documenting the tolerance behavior to ensure the implementation is clear and maintainable.

I have experience building TypeScript backend services, integrating blockchain-based workflows, and developing reliable systems with a strong emphasis on correctness, testing, and maintainability. I'm confident I can deliver a solution that aligns with the project's architecture and acceptance criteria.

[grantfox-oss]

🦊 GrantFox — @midenotch has been assigned to this issue as part of the Official Campaign | FWC26 campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #71)
2. Your PR will be reviewed by the AnonVote maintainers

Good luck! Track your progress on GrantFox.