Eth3rdEye.sol

This page will go through the smart contract to help understand how the logic works. It's written to remain accessible to a wide audience to maintain transparency and confidence in the system.

tip

Blockchain technical terms are hyperlinked to the glossary

Commit-reveal scheme

The smart contract logic follows a process known as a commit-reveal scheme. The commit-reveal is a sequenced order of operations that ensures the integrity of a value is maintained, and in our case kept secret, up until a specific step (the reveal stage). View diagram of commit-reveal sequence

In the case of Eth3rdEye, the commitment step consists of calculating the output of a hash-function using two values as the input:

• the target. In the first version, the target is selected from a list of 7 words/phrases.
• another secret known as the salt. This is a series of random letters and numbers that are hard to guess, like 34dp9Mdal6.

Thus, the targetCommitment that is saved in the Session can be defined mathematically as hash(target,salt). The resulting output of this function is used by a Tasker to start a session.

info

As an end user, you do not need to know to calculate the output of the hash function, or need to worry about creating a salt. The front-end website will guide you and perform the work necessary behind-the-scenes.

Contract Storage

  // Session management
  mapping(uint16 => Session) sessionsById;
  uint16 public lastSessionIndex;
  mapping(bytes32 => string) public predictions;

  // Accuracy management
  mapping(address => uint32) public accuracy;
  mapping(address => uint32) public attempts;

Starting a session

The Tasker is responsible for selecting a secret value. The sessionIndex identifies a session. The front-end will create the salt and hash the target to create the targetCommitment. Both of these are provided as arguments to the createSession function.

contracts/src/Eth3rdEye.sol

  function startSession( uint16 sessionIndex, bytes32 commitment ) public {
    uint16 nextIndex = lastSessionIndex + 1;

    require( nextIndex == sessionIndex, "Unexpected session index" );
    require( sessionsById[sessionIndex].targetCommitment == 0, "Session already started" );

    string memory emptyTarget = "";
    Session memory s = Session(commitment, emptyTarget, block.timestamp, msg.sender);

    sessionsById[sessionIndex] = s;
    lastSessionIndex = sessionIndex;
  }

A new Session is created and saved to the sessionsById mapping. The Session contains the following variables:

• commitment to store the target commitment
• a placeholder to store the revealed target. At this stage, an empty target string "" is set.
• the block.timestamp to enable time-based logic
• the msg.sender is the address of the wallet which invoked this transaction. This is how the Tasker of the Session is saved.