title: Hashing function with partially-reversable part
body: <p>Is there any known hashing algorithm, which for similar input returns similar output?
  I need it for creating 'tickets' without checking them against DB. My idea is that I create token carrying (userID and timestamp) (not reversable), and pass this token along with userID, and be able to check, if the token has given UserID, and, for example, was created 10 minutes ago - </p>
  
  <p>for example, change on first 4 bytes gives significantly different tokens, but with change on last 4 bytes the hashing function returns similar tokens.</p>