Passport for Airdrops

Airdrops are used to bootstrap communities around a particular project. They can also be used to reward early contributors to projects or contributors to the project's dependencies. Typically the project owners will identify in advance a set of addresses they want to airdrop a token to, and then send an amount to each address proportional to the value they have added to the community based on some set of predefined metrics. Matching rewards to real contributors is a very well-known problem in web3. Airdrops are anticipated in advance and "farmed" - meaning people attempt to achieve the eligibility criteria for the airdrop from as many addresses as possible to accumulate as much reward as possible.

These duplicate addresses linked to a single individual are known as Sybils. They are often considered to be detrimental to a project because they capture more value than they create and divert rewards from other contributors who might be more likely to continue to engage longer term.

There are also counterarguments that airdrop farmers help by adding visibility and hype to a project.

It is up to each project to decide its own philosophy about airdrop farming and how strictly to restrict access to provable individual human contributors.

However you want to set up your airdrop, it is likely that Passport can help.

This page will outline some of the ways you might want to use Passport to optimize your airdrop.

Gate access with Passport scores

Passport scores are metrics designed to increase as the evidence that a user is a real individual human accumulates. There is a large set of criteria that a user can verify to prove out their humanity:

• Ownership of certain web2 accounts with different interactions
• Web3 activities such as interactions with and ownership of ETH and NFTs, or participation in governance
• Biometric or KYC verification
• Participation in Gitcoin rounds
• Staking GTC tokens on yourself or community members staking on you

Each criterion has a weight associated with it. The Passport score is the sum of the weights from all the criteria a user can demonstrably satisfy.

Therefore, you can use the score as a measure of how likely it is that a user is human or Sybil.

You can set a threshold score that your users have to exceed to be eligible for your airdrop.

The higher the threshold, the more effort and/or capital a Sybil has to expend to create a fake account.

On the other hand, the higher the threshold, the more friction exists for your honest users, because they have to meet a higher burden of proof of humanity.

You have to determine the optimum threshold for your project - the higher the threshold the more likely you are to eliminate Sybils. The lower the threshold the less friction for users.

Passport's score threshold defaults

The Passport API provides a binary Sybil score (opens in a new tab) as well as a numeric score (opens in a new tab). This works by applying a threshold on the server and simply returning a true/false response depending on whether a user's score exceeds the threshold or not.

A user who exceeds the threshold is considered "likely human", while a user that does not meet the threshold is considered "likely Sybil". The default threshold value used by Passport is currently 20.

If you want to use the Passport default setting you can either retrieve a score and impose a threshold score of 20 yourself, or you can use the binary scorer directly to the same effect.

Note that you can also use your own weightings for each criteria if you want to more strongly weight certain actions that are important to your specific use case.

Points multiplier

Gating access by definition excludes some users from your airdrop. You might feel this is likely to be detrimental to your project. In these cases where participation is more important than eliminating Sybil's, you can use Passport scores to weight rewards. In this model, instead of excluding users with lower scores, you can use the score to scale the reward each user receives. This means no-one is excluded but users most likely to be honest participants are rewarded more.

An example scheme could be:

Base reward = 100 tokens
Passport score between 10 and 15 ➡️ base reward * 1.5
Passport score between 15 - 20 ➡️ base rewards * 2
Passport score over 20 ➡️ base reward * 3

Data analysis: criteria evaluation

Passport can also provide criteria evaluation as a service. For example, we can help you to determine the right criteria and thresholds for protecting your airdrop, and evaluate how many users would qualify under different scenarios. We can also help with retroactive removal of Sybils from your snapshot or participation list.