In principle this problem should be solvable with a zero-knowledge proof system. The law should allow for schemes that prove a performer is legal, identified,

In principle this problem should be solvable with a zero-knowledge proof system. The law should allow for schemes that prove a performer is legal, identified, etc., but that don't keep individual private details. Even if the site was completely compromised, all the attackers would gain is a single bit of data on each performer. The data would be worthless for personal identification