title: Ethereum: is validating wallet ownership possible?
body: <p>How can I validate that somebody owns a wallet address?</p>
  
  <p>Use Case:</p>
  
  <ul>
  <li><p>Wallet owner donates 10 ETH to the wallet address of a crowdfunding campaign</p></li>
  <li><p>Campaign decides to give perks (similar to kickstarter) AFTER the campaign has ended. </p></li>
  <li><p>If wallet owner who contributed is entitled to a perk, how could that owner claim that perk?  ideally they could provide a key that only the sender/receiver would know, but the campaign only has a transaction receipt and a wallet address which is all public knowledge.</p></li>
  </ul>
  
  <p>Is this crowdunding camping going to need to launch a smart contract?  </p>
  
  <p>:-/</p>
  
  <ul>
  <li></li>
  </ul>