A company that has no skin in the game and which business it is to be a trusted third party. One of the big audit companies would be my first thought. But there are many businesses that play this role (exchanges, clearing houses, etc).

At the end the job is technically quite simple. Maintaining a semi-public database. It's pretty black or white.

How do you account for rogue employees or hacks at the trusted 3rd party?

Equifax was a trusted 3rd party with no skin in the game.

Facebook was too (at least it was trusted by the west, the chinese never trusted it).

The same you prevent fraud in any industry, procedures, checks and controls. But at least that party has no incentive to fraud.