Cartesi Hackaton

readme.md

Credit Score flow

1. User or some App request a new Credit Score:

requestCreditScore(string taxId, uint256 loanAmount)

2. The Smart Contract make an API call through ChainLink, e.g.:

GET https://api.brx.finance/v1/credit-score?taxId=<tax-id>&loanAmount=<loan-amount>

3. ChainLink fulfill the request

4. The Smart Contract save it somehow and push a new payload to the InputBox:

bytes memory payload = abi.encode(response);
inputBox.addInput(L2_DAPP, payload);

5. Cartesi machine processes the payload (do the computations, run the risk model, etc)

6. Cartesi machine produces some output (maybe a Voucher to put in onchain, or event a Notice)

decode.py

import json
from eth_abi import decode

# inside handle_advance function
binary = bytes.fromhex(data["payload"][2:])
(json_string,) = decode_abi(["bytes"], binary)

json_string = json_string.decode("utf-8")
json_data = json.loads(json_string) # CustomerData payload

encode_decode.py

from eth_abi import decode_abi, encode_abi
# pip install eth_abi == 3.0.0

def encode(tax_id: str, loan_amount: float, json_payload):
    json_bytes = json.dumps(json_payload, separators=(',', ':')).encode("utf-8")
    hex_str = encode_abi(["string", "uint256", "bytes"], [tax_id, loan_amount, json_bytes]).hex()
    return f"0x{hex_str}"

def decode(hex: str):
    binary = bytes.fromhex(hex[2:])
    (tax_id, loan_amount, json_bytes) = decode_abi(["string", "uint256", "bytes"], binary)
    json_payload = json.loads(json_bytes.decode("utf-8"))
    return (tax_id, loan_amount, json_payload)

# params
tax_id = "26825555000166"
loan_amount = 10000
api_response = {
    "tax_id": "26825555000166",
    "tax_id_type": "cnpj",
    "tax_id_active": True,
    "company": {
        "start_date": "2017-09-01",
        "social_capital": 10000
    },
    "data": [
        {
            "source": "serasa",
            "score": 800,
            "total_debt": 1000
        },
        {
            "source": "scr",
            "score": 500,
            "total_debt": 2000
        }
    ]
}

# encode and decode
encoded = encode(tax_id, loan_amount, api_response)
print("encoded:", encoded)
# encoded: 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

decoded = decode(encoded)
print("decoded: ", decoded)
# decoded:  ('26825555000166', 10000, {'tax_id': '26825555000166', 'tax_id_type': 'cnpj', 'tax_id_active': True, 'company': {'start_date': '2017-09-01', 'social_capital': 10000.0}, 'data': [{'source': 'serasa', 'score': 800, 'total_debt': 1000}, {'source': 'scr', 'score': 500, 'total_debt': 2000}]})

EncodingExample.sol

// response in the CustomerData structure (see types.ts)

bytes memory payload = abi.encode(response);
inputBox.addInput(L2_DAPP, payload);

ICreditScore.sol

// SPDX-License-Identifier: Unlicense
pragma solidity ^0.8.25;

interface ICreditScore {
  struct CreditScoreInput {
    string taxId;
    uint256 loanAmount;
  }

  struct CreditScoreOutput {
    string taxId;
    uint256 loanAmount;
    uint8 score;
    bool qualified;
    uint256 timestamp;
    string[] sources; // serasa, spc, boa_vista, etc
  }
}

types.ts

enum DataSource {
  BOA_VISTA = 'boa_vista',
  SERASA = 'serasa',
  SPC = 'spc',
  SCR = 'scr',
  QUOD = 'quod',
}

enum TaxIdType {
  CPF = 'cpf',
  CNPJ = 'cnpj',
  // ...
}

interface DataSourceResponse {
  source: DataSource
  score: number
  total_debt: number
}

interface Person {
  birth_date: string // 'YYYY-MM-DD'
  capital: number
}

interface Company {
  start_date: string // 'YYYY-MM-DD'
  social_capital: number
}

interface CustomerData {
  tax_id: string
  tax_id_type: TaxIdType
  tax_id_active: boolean
  person?: Person
  company?: Company
  data: DataSourceResponse[]
}

// example
const response: CustomerData = {
  tax_id: '12345678901',
  tax_id_type: TaxIdType.CPF,
  tax_id_active: true,
  person: {
    birth_date: '1990-06-30',
    capital: 10000,
  },
  data: [
    {
      source: DataSource.SERASA,
      score: 800,
      total_debt: 1000,
    },
    {
      source: DataSource.SCR,
      score: 500,
      total_debt: 2000,
    },
  ],
}