Technology like U-Prove addresses exactly that scenario. Using it you could prove to a third party, using a government-issued credential, that you're over 18. Y

Technology like U-Prove addresses exactly that scenario. Using it you could prove to a third party, using a government-issued credential, that you're over 18. You wouldn't disclose anything else. The third party couldn't derive you gov. Id, and the government couldn't prove whom you provided your credential to - even if the two collude. Read up on it - the tech is really that good.