In our interactions with others, on- and offline, we regularly require or are required to provide personal information. We may, for example, need to prove that we are 18 or above to purchase alcohol; or we might need to prove that we are, or are not, a resident of a particular jurisdiction to participate in an IDO. The way we currently provide this information is inefficient because we are giving away more, potentially sensitive, personal information than necessary for the purpose. To prove that we are adults, for example, we might show our passport or ID, which shows not only our date of birth but also our legal names. Similarly, to prove that we meet jurisdiction requirements we might upload a proof of residence, such as a utilities bill or bank statement, revealing our address and potentially giving clues about our financial circumstances.