Index Calculation

In this example, we will calculate the price of an index composed of 60% ETHBTC and 40% LTCBTC. This involves fetching the prices for both pairs, performing weighted averaging, and converting the result into an integer value for on-chain use.

1. Modify the Request

   To calculate the weighted average of the ETHBTC and LTCBTC prices, modify the request to the Quex TEE module as follows:

   curl -X POST https://quex-api-endpoint/query \
   -H "Content-Type: application/json" \
   -d '{
         "request": {
           "method": "Get",
           "host": "www.binance.com",
           "path": "/api/v3/ticker/price",
           "headers": [],
           "parameters": []
         },
         "patch": null,
         "filter": "((.[] | select(.symbol == \"ETHBTC\") | .price | tonumber) * 0.6 + (.[] | select(.symbol == \"LTCBTC\") | .price | tonumber) * 0.4) * 100000000 | floor",
         "schema": "int256"
       }'

• The JQ filter specified in the "filter" parameter: ((.[] | select(.symbol == "ETHBTC") | .price | tonumber) * 0.6 + (.[] | select(.symbol == "LTCBTC") | .price | tonumber) * 0.4) * 100000000 | floor performs the following steps:

  • Selects the prices for both ETHBTC and LTCBTC from the JSON array.

  • Converts each price to a number.

  • Calculates the weighted average: 60% of ETHBTC and 40% of LTCBTC.

  • Multiplies the result by 10^8 and rounds it down to an integer.

• The "schema": "int256" indicates that the processed result will be returned as an integer value.

2. Certified Response Structure

   The certified response will be returned in the following format:

   {
     "signature": {
       "r": "0x...",
       "s": "0x...",
       "v": 27
     },
     "data": {
       "timestamp": 1696523461,
       "feedID": "0xabc123...",
       "value": 2389480
     }
   }

   The value field now contains the calculated index price, with the weighted average of ETHBTC and LTCBTC prices multiplied by 10^8 for convenient on-chain use. Note that only the final number is available on-chain, omitting all intermediate steps such as fetching the prices and performing the calculations. However, all these steps are encoded within the feedID and secured with the signature generated within the TEE module, ensuring the result's integrity and preventing manipulation.