One approach would be for offeror to encode the same "you're hired" message multiple times, using standard salary numbers for the encryption keys, and randomizi

One approach would be for offeror to encode the same "you're hired" message multiple times, using standard salary numbers for the encryption keys, and randomizing their order. If applicant is able to decode one of the encrypted messages with his desired standard salary (and somehow barred from trying multiple times with different numbers) then there'd be no third party necessary. Preventing multiple attempts would be the challenge with this approach. Alternatively, the "you're hired" message could itself be encrypted such that the applicant could send it back to the offeror to be decrypted. The challenge there is verifying the offeror didn't encode "$50,000" instead of "pay within range". The offeror encoding "no" and "yes" values and sending those two values (but not saying which is which) ahead of time would mitigate that problem, but again not if the applicant is able to run multiple numbers through the system (noting at which point the value changes). The best solution would be an algorithmic third party search engine which doesn't even mention the job or candidate to each other if there's no overlap in salary, taking less tangible things like years of work experience, education into account.