Proposal to significantly decrease wallet sync times fueled by community bounty

The Monero community has shown strong support¹ for Koe²’s proposal³ to reduce scan times with 1-byte-per-output view tag by donating to Seth⁴’s bounty⁵:

[..] anyone can freely donate to incentivize and fund the work required [..] -Seth

A working demo of view tags can be found in Koe’s Seraphis PoC branch⁶ (view_scan.h, mock_sp_core_utils.h⁷).

This change is projected to significantly decrease wallet sync times by 50-70% without sacrificing privacy:

I think we can easily reduce scanning by around 50-70% with 1 additional byte per output, call it the ‘view tag’, a reduction even taking into account Janus.

Furthermore, the increase in speed would also cover the scan time spent mitigating Janus attacks⁸:

[..] Janus might not increase scan times more than around 15-30% on average.⁹

[..] My recommendation is to roll this out in a hard fork alongside Janus [..] -Koe

Even with Janus accounted for and using the most conservative numbers, everyone using Monero wallets should still experience a decent speed increase. This would improve UX and potentially lead to an increase in adoption.

It is worth noting that, if implemented, this fix can not retroactively improve sync times. This aims to reduce wallet scan times of transactions created after the patch is implemented.

Bounty payout criteria

• Code is open-source
• Code is submitted to the Monero repo as a pull-request
• Pull request properly improves wallet sync
• Pull request is accepted into Monero’s code base after review

To start working on the project yourself, you should make your intentions public by posting a comment in the bounty’s thread².

Alternatively you can contribute some XMR to the bounty address posted by the Monero Bounties Bot. Your donation will be reflected in the comments.

Total Bounty: ~17.5 XMR (Oct 30, 2021)

Update:

• j-berman has started working on this bounty (PR ETA 2-4 weeks)⁵.

• PR #8061 submitted¹⁰.