WIP : Tezos support

General idea

The SigGating contracts are dedicated to provide a mecanism for off-chain validation of an action requested by a user. The request of a user (i.e. a contract invocation) is declared as a payload sent to NexeraSigner. The NexeraSigner retrieves the nonce for the user (from contract storage), specifies the expiration (block level) and compact all using a keccak hashing and finally signs this "keccaked payload". This off-chain signature is produced by Nexera signer. Then the produced signature and extra data (expiration, nonce, public key) are sent back to the user. The user can now send his transaction (which contains payload + signature + public key + nonce + expiration) to the smart contract that implements the signature verifiacition mecanism.

In this case the transaction fee is paid by the user.

The transaction could also be executed by an operator on behalf of the user. In this case the transaction fee is paid by the operator.

off-chain signture workflow

For a given calldata, the user receives from Nexera

• payload hash (keccak(key, nonce, expiration, calldata))
• nonce (custom nonce of the contract)
• expiration (block level)
• public key of Nexera signer role
• signature of the payload hash

Then the user build the transaction and invoke the exec_gated_calldata entrypoint. In order to be able to verify an off-chain signed message, the exec_gated_calldata entrypoint expects a txAuthData parameter which contains the following fields

• payload hash
• chain ID
• user address
• nonce
• expiration (block level)
• calldata (contract, entrypoint name, arguments)
• public key
• signature

The chain ID in Tezos varies depending on the network (see rpc nodes).

| Network | chain ID | | --------- | -------------------------------------------------------------------------------- | | ghostnet | NetXnHfVqm9iesp | | oxfordnet | NetXxWsskGahzQB | | mainnet | NetXdQprcVkpaWU | | sandbox | docker exec <docker-container-name> octez-client rpc get /chains/main/chain_id |

Smart contract architecture

Example of a standard TZIP-12 NFT token (using FA2 lib)

| function name | parameters | module | | ------------------- | ----------------------------------------- | ----------------- | | setSigner | address | NFTMINTER | | mint | mint | NFTMINTER | | mint_gated | mint | NFTMINTER | | dispatch | calldata | NFTMINTER | | exec_gated_calldata | txAuthData | NFTMINTER | | transfer | FA2.NFTExtendable.TZIP12.transfer | FA2.NFTExtendable | | balance_of | FA2.NFTExtendable.TZIP12.balance_of | FA2.NFTExtendable | | update_operators | FA2.NFTExtendable.TZIP12.update_operators | FA2.NFTExtendable |

Example of a proxy contract

The verification of the signature and the controls (expiration) can be splitted into 2 contracts

• a proxy that verifies the signature and dispatch the calldata
• a fa2 contract that accepts a calldata (only from the proxy) and process it

Deployments

The nft minter contract has been deployed

| network | address | | -------- | ------------------------------------ | | Ghostnet | KT1Ko4fwVmzNfZe3pSYFjhPYQj6GUTU3dAPa | | Mainnet | N/A |

Publish LIGO library

If the Ligo library (SigGating) is modified it has to been re-published in the LIGOlang registry.

• Install ligo executable locally install instrauctions
• Log in: ligo registry login

FrankNexera
*******

• Simulate publish: ligo registry publish --dry-run
• Publish: ligo registry publish

Then smart contracts can use this library by specifying the version in a ligo.json file.

{
  "dependencies": {
    "@ligo/fa": "^1.4.2",
    "@nexeraid/sig-gating": "^1.0.0"
  }
}

Contracts code

Inside the tezos-sig-gating-contracts folder

make install
make scripts_install
make compile
make test
make sandbox-start
make integration-test
make sandbox-stop

The following sections describes in detail the command lines to launch tests and deploy and interact with the contract.

Setup

Install the LIGO libraries make install. In our case we may use FA2 library to use NFT's in our test scenarios

Install node modules for interacting with smart contracts in TypeScript make scripts_install.

Compiling

make compile

The compilation produces 2 files (TZ file and JSON file) which are stored in the compiled folder. The contract in JSON format is used by scripts for deployment and interactions.

Testing

make test

Launch LIGO tests

Integration testing LOCALHOST

A local network (called sandbox) can be used for testing before deployment on Testnet.

• Run the sandbox make sandbox-start
• Launch a single test script with make integration-test that deploys a contract and executes a "mint off chain" (and test failure cases).
• Stop the sandbox make sandbox-stop

The sandbox

Launching the sandbox will create a running docker container. The docker ps command will show you the running container. Default available users can be shown with docker exec tezos-sig-gating-contracts-sandbox oxfordbox info

Two extra users have been added (in script run-sandbox). We can check existing addresses

docker exec tezos-sig-gating-contracts-sandbox octez-client list known contracts

We can also check the balance for these accounts with

docker exec tezos-sig-gating-contracts-sandbox octez-client get balance for alice
docker exec tezos-sig-gating-contracts-sandbox octez-client get balance for bob
docker exec tezos-sig-gating-contracts-sandbox octez-client get balance for frank
docker exec tezos-sig-gating-contracts-sandbox octez-client get balance for user

Get the chain_id

docker exec tezos-sig-gating-contracts-sandbox octez-client rpc get /chains/main/chain_id

Manual interaction (separate scripts)

Deploy a NftMinter

Once the sandbox is running we can deploy a contract. The script local_deploy_nftminter.ts deploys a contract (NftMinter) on behalf of alice (considered as admin). This script can be launch with make localdeploy.

docker exec tezos-sig-gating-contracts-sandbox octez-client list known contracts

Off-chain signing

The script local_sign.ts is a tool to sign a payload on behalf of bob. (For the moment the inputs must be specified inside the file. Need improvment !).

make localsign

for a given signer(privatekey) and a payload, this script produces a signature of the given payload signed by the public key (related to the private key) This command should display something like this.

sig= {
  bytes: '4829ce5f20426c2e4f2107cba21c466fa06b5db70d25ff2ff3af8ee74ee7a489',
  sig: 'sigtnFrMku2Yae9V4rQ6mp6bFVMJ32d5eurqAExNzcfDkTUnYHfMbLkjdANR2veQLszQdaJ6ijA1xS48BuKDW4uLscKVyrcW',
  prefixSig: 'edsigu4biyQyoJUmgCg49Y8d13tY1887xbiXWEWuygizbfZmQncUtAFWRqns5R1eijsXERx7CDcW5zdvCnvE6yMr36PwiGVKCSu',
  sbytes: '4829ce5f20426c2e4f2107cba21c466fa06b5db70d25ff2ff3af8ee74ee7a489eb5d72f6e40744c43dc5bb8534d18a530669af464ef3ed7d38340eae0cf4c850230bccb71495e6214f36991e0635dec25fa6d534d3179f42f96b100317f8f40c'
}

The prefixSig field is the signature that must be used when invoking the contract.

Mint local

make localmint: Alice sends a message (signed offchain by bob) to the NftMinter contract. (the message is a call data asking user to mint asset 1).

Expected output:

Waiting for Exec_gated_calldata on KT1UgwgtRhh2FYwoc38sPKDsqPkjDRpEoFio to be confirmed...
tx confirmed:  ooTY3qhAMvhNwpnxA2roTaMiuxuVKy8RwueB9sfYJmUPCC2bhW4

Display contract storage !

TODO need improvment Verify that the asset 1 is owned by "user". The following command display the owners for 3 first assets.

make localdisplay

Integration testing TESTNET

Off-chain signing

The script signAuthData.ts is a tool to sign a payload. (For the moment the inputs must be specified inside the file. Need improvment !). Fill

make sign

for a given signer(privatekey) and a payload, this script produces a signature of the given payload signed by the public key (related to the private key) This command should display something like this.

sig= {
  bytes: '4829ce5f20426c2e4f2107cba21c466fa06b5db70d25ff2ff3af8ee74ee7a489',
  sig: 'sigtnFrMku2Yae9V4rQ6mp6bFVMJ32d5eurqAExNzcfDkTUnYHfMbLkjdANR2veQLszQdaJ6ijA1xS48BuKDW4uLscKVyrcW',
  prefixSig: 'edsigu4biyQyoJUmgCg49Y8d13tY1887xbiXWEWuygizbfZmQncUtAFWRqns5R1eijsXERx7CDcW5zdvCnvE6yMr36PwiGVKCSu',
  sbytes: '4829ce5f20426c2e4f2107cba21c466fa06b5db70d25ff2ff3af8ee74ee7a489eb5d72f6e40744c43dc5bb8534d18a530669af464ef3ed7d38340eae0cf4c850230bccb71495e6214f36991e0635dec25fa6d534d3179f42f96b100317f8f40c'
}

The prefixSig field is the signature that must be used when invoking the contract.

Deploy contract on ghostnet

This command deploys the NftMinter contract on Ghostnet. It uses the deploy_nftminter.ts script. (For the moment the initial storage of the contract must be specified in the file. Need improvment).

make deploy

Interact (call entrypoint)

Once the contract is deployed , we can interact with it. The following command invoke the Exec_gated_calldata entrypoint of the NftMinter contract. (For the moment the parameters (nonce, expiration, calldata, public key, signature, useraddress) must be specified in the file. The signature parameter can be forged with the make sign command. Need improvment).

make mint

Once the transaction is accepted, you can check on an indexer (TZKT for example) For example, our ghostnet contract

Limitations

Remark on transaction ordering

When constructing the signature , the actual nonce ofr the user is taken into account in the payload (to prevent replay attack). But it also implies that if a user submits 2 payloads (in this order calldataA and calldataB) then the calldataB cannot executed before calldataA.