3 ms·

Why not something computationally expensive? Bcrypt this value 10000 times to continue

• sodality2 5y ago
  Ideally you'd have something that's hard for the client but easy for the server to verify, though. so maybe prime factoring?
  • tshaddox 5y ago
    Or, the server provides a random string of bits with length n and requires a string of bits with length n+m that starts with the provided n bits and whose SHA-1 hash begins with 20 zero bits.
    • wruza 5y ago
      What nonceness!
• kalleboo 5y ago
  Spammers use botnets, so they have plenty of computation available
  • immibis 5y ago
    And if every site does this, they have plenty less. Imagine if you can only attempt your spam 20 times per second instead of 20000
• iszomer 5y ago
  Imagine when a miner is used as Captcha and would only pass when a certain amount has been mined..