Smart Token Labs Presentations & Workshops, 30 Nov 2021

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From YouTube: Ethereum NFT Lock

Description

Ethereum NFT Lock, works with August/Yale's Smart Lock
https://github.com/AlphaWallet/TokenScriptDoorClient

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Ethereum devs, what I'm going to be talking to you today is about a way to add ethereum power to your august or yale front door lock via erc 721 tokens. You might have heard of this particular type of nfts. First, through cryptokitties, the people auction, maybe and lately board apes, said, run axes and many many others.

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Now today, we're actually going to be using nfts as a utility token. So there's going to be some some function attached to the token which is operating our yale log. So the cool thing about using nfts for access control is you can define all of the rules. You can define how exactly how the token is going to be used and who can use the token.

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For example, you can set up a rule so that only you can transfer the tokens. So when you transfer them to another user, they can only hold the token you can set time locks. You can.

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You can burn the tokens at any time or you could even set up an auction so that the winner of the auction will automatically receive the token and then for a limited amount of time they can have access to your apartment or whatever you're using for access.

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So today, we're actually going to be using the token script framework to to give us a nice, quick user interface for the log, and um I'm going to talk you through how to set up each component like the um the interface to the yellow, lock itself, we're going to set up the we're going to mint some door tokens um we're going to write the token script and then we're going to put them all together and see if it see how it works and then finally I'll take you behind the scenes to show you exactly what's happening: okay, first, let's have a quick look at the lock, so here's the uh standard, yellow lock um with an app that connects to it and I'm just gonna open the front door for you.

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Okay, you open and close it up.

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So this is the default way that we uh that we operate the yellow okay, let's get started so the first thing I want you to do is to clone the token script door client. So first of all go to the alpha wallet: github repo, just github.com, alpha wallet, open up the tokenscriptdoor client, which you'll see there's a public repo and there's a few instructions there, which you can go into if you wish.

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uh What we're going to do now is just clone this repo, so just grab a link open up your console.

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It should come down now. um This is actually a xamarin framework, app, so you're going to be using visual studio.

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So we've got that installed here so pop that guy open, so you'll need visual studio with the xamarin framework, so cloning that straight from the repo open it up and you'll, see. There's if you open up main activity, you will see there's a bunch of there's a bunch of keys that you have to find here. So the instructions to find those keys are in the github repo instructions.

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You'll need to already have a working yale, lock installed and probably a rooted phone.

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So after setting up your keys, what I want you to do is uh install this onto a test phone that you have so in my case, I have a spare google pixel, one which I like to use and set that up.

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Click, install it'll go through the build and it is going to deploy. So here we go. It's just deployed.

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And you can see it's um it's connecting to the bridge.

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Okay, so we are going to deploy this app now, so this is from the uh the xamarin project. It's opening up and it's going to now be scanning for the log to try to find the lock it's looking through the bluetooth devices they go. It's found it. Let's do a quick test to make sure this works.

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And just running through its tests, there we go okay, so you can see that this is.

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Communicating with the the august lock okay, so now, we've established that the thing we want is the device address. So this address here is created when the when the app first runs it stores it and it's persistent address, that's used each time now. This address doesn't actually do anything other than doing ecdsa cryptography. So there's no tokens on this address. So what I'm going to do is just click that link and I should get a yeah there. We go copied address to clipboard. So that's what I want.

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So I'm gonna go swap over to telegram and pop that link oops pop that link into telegram there. We go.

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The next thing we're going to do is mint our nft. So if you go back to the token script door, client repo- you can see, there's this solidity entry token file here, just click on that guy click on the solidity file.

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It's a super easy way to do it click raw. um Then this is here's. The solidity contract that I've got it's a standard erc721 from open zeppelin, but I have made one small modification, which is: I have added this mint using sequential token id just to make it super easy to mint new tokens.

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So, let's uh go to let's open remix, so remix is how we're going to deploy the token. So here's the standard thing it's just remix.ethereum.org.

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You will need the metamask plugin, which I already have so I'll open that up and connect my test account which I just created here. So I have this test account. So the next thing I need to do is just get some uh get some a ring b. So I shall just go to the chain link faucet.

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Copy my address in ask 0.1 not a robot.

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So we are back again and let's go to remix and yeah. You can see that we've received our 0.18 from the faucet. So let's use this thing. What I'm going to do is create a new file call. It.

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Create a new file call it.

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And you can see, we've got a blank file here, so let's go back to our contract, just copy paste that guy in there he goes.

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Now you can call it something else whatever you like. I've set up a little surprise for you guys, so I've actually copied the board apes metadata.

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So when you open this token in your wallet, it appears that you've got um board apes, but you haven't really: okay, okay, so open up the deploy and run transactions window click on injected web3, and you should see your account and you say yes, okay, 0.1 ethers, so that should be enough to do everything we need to do today make sure that you're selected the right, the right class to burn so that's door, token, dot, sol and finally deploy so metamask should pop up and then we're asked to confirm the transaction.

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And now we just wait for the transaction to finalize it. Shouldn't take long and rank b is usually pretty quick.

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Just there we go so.

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Contract here and oh there's, the transaction hash, so here's um here's the contract functions now. What I'm going to get you to do is to mint some door tokens so we're just going to call this utility function that I added this custom utility function to just click mint using sequential and we should get the metamask popup confirm that you're happy to mint. Then, let's mint one more just for fun.

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Okay, so now I should have two of these tokens in my wallet. What we're going to do now is transfer this wallet to alpha wallet so so that we can use a token script. So, to do that, you have to open the wallet, see we've just we've lost a little bit of ether burning the transaction um yeah. The mint function is still pending.

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What we're going to do now is just take out the private key, so the method I'm going to show you don't use this for a real account. It's only good for test account, so we go.

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Account details.

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Export private key you are gonna, have to type in your.

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Your account password open it up and there's my private key there's nothing on this. This key apart from that not point not one ring b, so just copy that into the clipboard, and I'm going to show you a very insecure way of transferring it um again. Don't do this with the real key, so I go to saved messages in telegram paste. The private key in there send it off and now that's available on my device.

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The next thing to do is to set up the token script so to do that, we're going to go back to the tonescript door, client, repo, open up the tonescript, folder and you'll. Do this on your local computer and you'll find this lock entry.xml file. Now I want you to open that up in visual studio, so it should look something like this. So this is a tokenscript file and it comprises of xml.

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It's an xml wrapper around some definition, xml definitions. We have css here you can see and we have some html and javascript and all these are ways of programming user interface onto tokens. So we only actually need to edit two things in this file to get it working for you. We just um the first thing. Is our contract address, so what I want you to do is to go to remix, which, hopefully you still got open.

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You can see under deploy contracts. You can see the function, the contract that we just deployed and check the name here. Let's see door tokens here, so, let's copy the contract address here, go back to visual studio code and paste that that's the first step. So the next thing I want to do is look search for iot in this folder you will see in the javascript snippet you'll see iot address. This is the address of the remote client um that we found in a previous step.

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So if you go to your telegram, we recorded it there. If you remember so here, it is let's just pull that out and paste it in and that's it you're done with the token script.

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And now you're going to take that contact address, go back to the xamarin app and find the function check. Token balancer unlock and you are going to put your new token address.

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Now, what you're going to do is find the token script that you just edited in your directory folder, and you can just drop that straight into your telegram.

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There we go send that guy and now what you're going to do is open that in alpha wallet,.

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Okay, so the next step is to import the private key that we exported from metamask into alpha wallet. So if you haven't already installed our wallet from the play store, then please do that now, let's um grab this private key.

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And I'm going to switch to alpha wallet, settings change, I'm going to import the wallet, it's a raw private key, so you need private key.

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And I am going to import that guy, so I've just imported it. Let's switch over to the wallet and you can see, we've already got the door tokens imported. um Let's just give it a few seconds and it should spot our rink b yeah there. It goes okay. So it's seen our ring bit seen our door tokens. So um before we install the token script. Let's just have a quick look at the door. Tokens and oh board apes, great um okay! So that's okay!

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Now we're going to upload the token script into alpha wallet, so the token script that you previously copied to telegram. Let's go into there. You can see that um the first intent is alpha wallet. So let's go into our wallet, it opens up and you can see straight away that um the issuer of the token is now token script debug.

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So that tells us that we've been successful. Let's click on here you can see it's uncertified when, after you've finished debugging your token script, you can sign it and then, when after it's been signed and uploaded to the repo server, this will then become a nice green tick. Just like a website certificate, okay, so we're going to click on one of the tokens that we've got. You see a little history there. Let's um the token script contain two verbs: we've got a mint verb to mean new tokens and we've got an interverb.

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So, let's, um let's click on enter and you can see that we've just received the challenge from the door, uh the door client. So, let's, let's click enter. So I'm now being asked to do a sign, personal message on this challenge. So I'm going to go ahead with that. I'm just going to use my fingerprint okay, let's go so the sign successful and there you go and it's just transmitted to the um the app.

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So let's try again so let's go click into so this should actually the verb should actually be toggle.

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Technically, since.

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And it's just locked, so finally, here's what's happening behind the scenes. So the first thing we have when this tone script door. Client first opens it, creates its own private key.

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um Once it's got that private key, as you saw what it does then so on opening. It will then try and connect itself to the token script bridge. So what happens uh as it logs into the token script bridge that will then send back some challenge. Bytes what happens now? The client will sign those challenge. Bytes return, the signature back to the proxy bridge.

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What happens then? The proxy bridge ec recovers the token script door client address and then creates a mapping um of the token script door client as a tcp client against this against its um ethereum address. So now we've got the client connected to the bridge. So what happens? Next?

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The user opens the door entry token in his wallet and the token script engine will ask for a challenge, so it'll send a challenge to it'll say: please give me a challenge to token script bridge the token script bridge just forwards that to the uh the target address, which will be the token script door. Client, the token script door client generates a challenge which looks something like this and then transmits it back to the token script engine. So this just happens via javascript promises within the token script, the lock entry.xml that we just edited.

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So now we are displaying this uh this um this challenge. So what happens now? The user, through the alpha wallet, app signs this challenge um and then transmits the signature back to the token script bridge. So that's now the turnstill bridge is aware of this signature and also the target that we're speaking to so. It then forwards the signature to the door client via this mapping and then what happens is the door client will recover the alpha wallet address, knowing the challenge and being given the signature.

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So now that it has the address the verified address of the um the wallet, it can then check to see if there's any balance of the door entry tokens at this address and if there is it, opens the door.

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And that's gonna do it. So if you enjoyed this video, please um send us some feedback and like, if not also send us some feedback too, and let us know what you think and if you would like to get started with tokenscript.

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There's uh plenty of people here at smarttokenlabs who can put you on the right guidelines, there's also a white paper. You can read: that's in the github.com tokenscript repo and there's plenty of tonyscript examples on um on the alpha wallet, repo and the typoscript repo.

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