About this guide This guide will probably be most helpful for people who have already used StarkNet some. I've been implementing a project on StarkNet full time for the past 3-4 weeks, and this contains some of the lessons learned. Questions or suggestions: ping me on twitter @RoboTeddy. Sidebar for anyone who is new to StarkNet Public Service Announcement: You don't need to understand how STARKs work in order to use StarkNet! Thanks to hard work by the Starkware team, you can just learn and use Cairo (a programming language) and StarkNet (a place to deploy programs written in Cairo). The best way to learn is by following the StarkNet documentation. You can learn any Cairo you need as you go by using the Cairo documentation and completing exercises in the cairo playground.

The problem with signs A lot of challenges these days are due to mistakes people make in their signs. For example, of the 13 registrations that are challenged while I'm writing this, a whole 10 of them (77%) are about problems with signs: https://app.proofofhumanity.id/profile/0xc19c81a04055c1e398f52e7cc28b4c39d3b0e2c9 https://app.proofofhumanity.id/profile/0xe98829b18767db78434cde5c0367225444e32b85 https://app.proofofhumanity.id/profile/0x0589a39ae8b8b5f09d1e19af08b2190009d4a294 https://app.proofofhumanity.id/profile/0xe385fa81138e777a7ce46e44c4f0aa10ad78e2dd https://app.proofofhumanity.id/profile/0x8377548a05081ab027ee3b5bff208bd3c40a40fa https://app.proofofhumanity.id/profile/0xe11d5a0e63af66befc7c0b228c122323a600efff https://app.proofofhumanity.id/profile/0x9e1fe3cbdcfd651059da35b781c73083563a1bfc

Decentralized quadratic funding, democratic voting, fair airdrops, basic income, etc depend on there being a set of keys which are each controlled by a unique person acting under their own agency. Services like Proof of Humanity, BrightID, Idena, etc attempt to provide this guarantee by having a process for approving particular keys. Economic security Ideally, it would be free for someone to obtain their first approved key, and then any subsequent approved keys would have infinite cost. In practice, there will be ways for a single person to collect more than one approved key. We can quantify security by asking how much it costs an attacker to obtain their 2nd, 3rd,... nth approved keys (we can call these additional keys illicit keys.) Let's call the cost of acquiring $n$ illicit keys $C(n)$ Let's call the value of having $n$ illicit keys $V_{attacker}(n)$

Proof of Humanity could become a world-wide standard that allows the decentralized applications of our future to be influenced by people rather than money. If we can't count people, people won't count! How do we make it happen? We can accelerate Proof of Humanity's growth by including as many people and projects as possible. The more we have, the faster others will join. Everyone will want to use the identity system that everyone is already on because it's convenient. So: we should include as many people and projects as possible. PoH should be maximally inclusive. Maximally including people Participating in Proof of Humanity should be:

The purpose of proof of humanity (PoH) is to offer sybil resistance for things like quadratic funding, universal basic income, etc. Dishonest parties that want to warp quadratic votes, receive extra basic income, etc will have an incentive to gain control of multiple proof of humanity registrations. If attacks are cheap, PoH has limited utility. A core metric for PoH: what's the market price of an illicit registration? The Puppeteer Attack The cheapest attack I know of costs on the order of $10 [1]: An attacker (puppeteer) can just pay a random person off the street (a puppet) ten dollars for the privilege of taking a photo and video of the puppet holding a sign and uttering the PoH registration sentence. The puppeteer can then take these media files and use them to generate a registration in PoH. A puppeteer could head to an area with lots of relatively poor people and use a stack of $10 bills and public key signs and collect a ton of photos/videos that allow them to register lots of times.