SSI SBT

Self Sovereign Identity based Soulbound Tokens (SBTs).

SBTs are on-chain tokens holding personal information that can't be transfered (soulbound). On Ethereum, they're implemented using ERC721 but restricting burns and tranfers. On Tezos however, they're implemented using a custom smart contract exhibiting the same behavior as the Ethereum one. This can be useful for on-chain dApps, in the gaming or DeFi worlds for instance, to permission access without going off-chain.

This app is meant to be used by Issuers of Verifiable Credentials to generate the related SBTs for users who need to get permissioned access to dApps. The minted SBTs can be consumed by dApps that need to verify a user's credentials.

Contract addresses

As a dApp (verifier), to verify if a user possesses a given token, you'll need to access the relevant Smart Contract.

Altme DeFi Proof Of Compliance (DEFI)

This is the address for Altme's DeFi Proof Of Compliance (DEFI) token (https://issuer.talao.co/nft/defi)

blockchain	address
ETH Testnet	0x2285A09cABeb0D07005E86B71Af8e6C7e0497f29
ETH Mainnet	0x240863E65b2ace78eda93334be396FF220f14354
BSC Testnet	0x1589257BBfA909B1b3D17148a7a3D27A37ee92ba
BSC Mainnet	0x240863E65b2ace78eda93334be396FF220f14354
Polygon PoS Testnet	0x240863e65b2ace78eda93334be396ff220f14354
Polygon PoS Mainnet	0x240863E65b2ace78eda93334be396FF220f14354
Tezos Ghostnet	KT1AcYTy6KGv8cpRUgfutFfg2HkphzGeub4t
Tezos Mainnet	KT1WDYsU9EHL1c4Zm2fd2YtqVMpFZ66TasqK

/!\ Those addresses may change, contracts are not updatable

Soulbound Token API on EVM compatible blockchains

The solidity code for the Soulbound Token can be found in ./sbt-contract-evm.

The contract ABI can be found in ./sbt-contract-evm/abi.json.

It's implementing the ERC721 interface from OpenZeppelin and will work like most ERC721.

The main differences are:

• transfers are blocked.
• we record the token's creation date so we can check if it has expired.

Verify that a user does own a given token

require(soulboundToken.balanceOf(address) > 0, "address doesn't have this token");

Burn a token

A token owner can burn their own token via a Solidity call.

soulboundToken.burn(token_id);

Check expiry on-chain

As a verifier, you may check if a token is still valid by retrieving its timestamp:

uint256 creation_date = soulboundToken.tokenTimestamp(token_id);

require(block.timestamp < (creation_date + 3600 * 24 * 60), "token has expired");

Soulbound Token API on the Tezos blockchain

The JsLigo code for the Soulbound Token can be found in ./sbt-contract-tz.

An SBT contract is a map of owner as an address and an ipfs_url for the token's metadata. Another map of owner and timestamp records the token's creation date.

The Smart Contract offers 3 views to:

1. Retrieve a token_uri given an owner's address
2. Retrieve the token_creation_date to verify that it hasn't expired
3. Verify if an owner has a token given a KT1 address.

Install

View the Install guide if you want to run this service locally or deploy it to another environment.

REST API

Only token issuers should need to use this API. Please check the Postman Collection to exercise it. On-chain verifiers should use the Smart Contract's relevant methods.

This API works the exactly the same whether consuming an EVM blockchain or a Tezos blockchain. The X-BLOCKCHAIN header needs to be set to specify which blockchain to access.

Example request:

Mint

Mint requires a transfer_to address and an ipfs_url url. Also make sure to set the X-API-KEY for authentication, as well as a X-BLOCKCHAIN header to specify the blockchain to mint the token to.

curl --location --request POST 'localhost:3000/mint' \
--header 'Content-Type: application/x-www-form-urlencoded' \
--header 'X-API-KEY: testKey' \
--header 'X-BLOCKCHAIN: BINANCE'
--data-urlencode 'transfer_to=0x123address' \
--data-urlencode 'ipfs_url=ipfs://ipfs-url'

Response:

{
    "network": {
        "name": "bnbt",
        "chainId": 97
    },
    "contract_address": "0x1589257BBfA909B1b3D17148a7a3D27A37ee92ba",
    "tx_hash": "0xae12071058be915466e66f1044b889ac0508d580ebfda59773396aaf88c57b21"
}

Burn

Burn requires an address_for address that represents the wallet public address that we want to burn the token for. Also make sure to set the X-API-KEY for authentication.

curl --location --request POST 'localhost:3000/burn' \
--header 'X-API-KEY: testKey' \
--header 'X-BLOCKCHAIN: BINANCE'
--header 'Content-Type: application/x-www-form-urlencoded' \
--data-urlencode 'address_for=0x123address'

Response:

{
    "network": {
        "name": "bnbt",
        "chainId": 97
    },
    "contract_address": "0x1589257BBfA909B1b3D17148a7a3D27A37ee92ba",
    "tx_hash": "0x698c9601f8647c09e300ca62f3c5d857189d9cf9e61de1881b550649a13f583f"
}

Info

Info returns some useful information about the network being used (the blockchain that runs the smart contract) as well as the contract address and name of the token. This endpoint lists all the available blockchains. The networkName value can be used to specify the X-BLOCKCHAIN header. When specified, it will mark the related network as selected. this could be useful to verify that the header works and maps to an linked blockchain.

curl --location --request GET 'localhost:3000/info'

Response

[
    {
        "networkName": "BINANCE",
        "selected": false,
        "info": {
            "network": {
                "name": "bnbt",
                "chainId": "97"
            },
            "contract_address": "0x1589257BBfA909B1b3D17148a7a3D27A37ee92ba",
            "name": "Proof of DeFi compliance",
            "symbol": "DEFI"
        }
    },
    {
        "networkName": "TEZOS",
        "selected": false,
        "info": {
            "network": {
                "name": "tezos",
                "chainId": "NetXnHfVqm9iesp"
            },
            "contract_address": "KT1JyVbngXYQy1FrbAJV4tQQaZwRmHj9o2jL",
            "symbol": "DEFI",
            "name": "Proof of DeFi compliance"
        }
    }
]

Has

Checks if a wallet has a token. The wallet to test is set in the url:

curl --location --request GET 'localhost:3000/has/0xCdcc3Ae823F05935f0b9c35C1054e5C144401C0a' --header 'X-BLOCKCHAIN: BINANCE'

Response:

{
    "network": {
        "name": "bnbt",
        "chainId": 97
    },
    "contract_address": "0x1589257BBfA909B1b3D17148a7a3D27A37ee92ba",
    "has_token": true
}

Token info

Retrieves the creation timestamp and token uri for a token. The token id is set in the url

curl --location --request GET 'localhost:3000/token/0xCdcc3Ae823F05935f0b9c35C1054e5C144401C0a' --header 'X-BLOCKCHAIN: BINANCE'

Response:

{
    "network": {
        "name": "bnbt",
        "chainId": 97
    },
    "contract_address": "0x1589257BBfA909B1b3D17148a7a3D27A37ee92ba",
    "token_uri": "ipfs://Qmf8Y4u1hYHaNYdhUUcvtKn3XM8JUk86zeqSjLvRkSoMsu",
    "token_creation_timestamp": 1684916584
}