m4tsuri / ethernautwp

Ethernaut WriteUp

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• Keywords: Rust, Binary Security 🔐, Static Analysis, Blockchain

ethernautwp's Issues

Error in 12-privacy challenge

In this challenge: 12-privacy

arg1 is 0x03, var0 is 0x02, so storage[var0 + arg1] refers to 0x05 slot. As it's 0-indexed, I think it's the sixed slot, but you said it's fifth slot.

In contract source code, variabilities :

  bool public locked = true;   // first slot
  uint256 public ID = block.timestamp;  // second slot
  uint8 private flattening = 10;  // third slot
  uint8 private denomination = 255;  // third slot
  uint16 private awkwardness = uint16(now);  // third slot
  bytes32[3] private data;  // forth, fifth, sixth, seventh slot

And in unlock function:

  function unlock(bytes16 _key) public {
    require(_key == bytes16(data[2]));
    locked = false;
  }

That's why bytes16(data[2]) refer to the first 16 bytes of the sixth slot.