Does SPYx / USDC match its issuer's published contract?

QED signs a canonical JSON payload. Fetch the public key from /.well-known/qed.json, then check the signature against this payload.

Canonical JSON

{"block":26241029,"chain":"ethereum","checked_at":"2026-10-21T12:39:31Z","dev":false,"expires_at":"2026-10-22T12:39:31Z","issuer":"Backed xStocks","pool":{"base":{"address":"0x90A2a4c76b5D8c0bc892A69EA28Aa775a8f2dD48","balance":"1899414586654155","decimals":18,"symbol":"SPYx"},"chain":"ethereum","dex":"uniswap-v3","pool":"0xAfdd3BdC20A31652e48b56B73952Ca324f544575","quote":{"address":"0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48","balance":"21410145","decimals":6,"symbol":"USDC"}},"quote_share_of_supply":6.299599584565916e-8,"reads":[{"block":26241029,"method":"eth_blockNumber","params":[],"result_hash":"782a4dd0f91a2d9483b15cce6f69f2fbeae528e1b567cced380554b118974c69","slot":null},{"block":null,"method":"eth_call","params":["0xAfdd3BdC20A31652e48b56B73952Ca324f544575","token0()"],"raw_result":"0x90a2a4c76b5d8c0bc892a69ea28aa775a8f2dd48","result_hash":"cea64c28d119727097c6477c099ad4a765988e1cd2c523476d2d061294a1ad23","slot":null},{"block":null,"method":"eth_call","params":["0xAfdd3BdC20A31652e48b56B73952Ca324f544575","token1()"],"raw_result":"0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48","result_hash":"6239f262cd1d947b947081c9eba6e8771378942478e1d48654f4f132ebb96021","slot":null},{"block":null,"method":"eth_call","params":["0xAfdd3BdC20A31652e48b56B73952Ca324f544575","getReserves()"],"raw_result":"false","result_hash":"076de6e730df0b4c3860877a0f619c6ac11f8aefd78313ac793a2a703c026869","slot":null},{"block":null,"method":"eth_call","params":["0xAfdd3BdC20A31652e48b56B73952Ca324f544575","slot0()"],"raw_result":"true","result_hash":"18d10c7d2b4b04aaf04254d1ae5d655a5dc0407cbcdd5a8c3986e985370f36ee","slot":null},{"block":null,"method":"eth_call","params":["0xAfdd3BdC20A31652e48b56B73952Ca324f544575","factory()"],"raw_result":"0x1f98431c8ad98523631ae4a59f267346ea31f984","result_hash":"24b698329e82b3994906dfbd01281d9a6f12f65aa59de65831657e6e928d4c80","slot":null},{"block":null,"method":"eth_call","params":["0xAfdd3BdC20A31652e48b56B73952Ca324f544575","fee()"],"raw_result":"3000","result_hash":"53232d7da9fd2a1931dcd44af08ec415dd52ab8ecc4037ef5e68eb3753978a2e","slot":null},{"block":null,"method":"eth_call","params":["0x1F98431c8aD98523631AE4a59f267346ea31F984","getPool","0x90A2a4c76b5D8c0bc892A69EA28Aa775a8f2dD48","0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48","0xbb8"],"raw_result":"0xafdd3bdc20a31652e48b56b73952ca324f544575","result_hash":"eb48eee9e57274ee1cb86d4f1cc533d63953b06ecb1dd2b21e5081e364e79a0b","slot":null},{"block":null,"method":"eth_call","params":["0x90A2a4c76b5D8c0bc892A69EA28Aa775a8f2dD48","symbol()"],"raw_result":"Some(\"SPYx\")","result_hash":"de41d2c14fa73c8e3ea34e4093b99a9165ac26bef56a7d98b711bdb990d48466","slot":null},{"block":null,"method":"eth_call","params":["0x90A2a4c76b5D8c0bc892A69EA28Aa775a8f2dD48","decimals()"],"raw_result":"Some(18)","result_hash":"c14f173ff30df32f36fac2ea29d9a20482082428fd32b58be5433d310884f764","slot":null},{"block":null,"method":"eth_call","params":["0x90A2a4c76b5D8c0bc892A69EA28Aa775a8f2dD48","balanceOf","0xAfdd3BdC20A31652e48b56B73952Ca324f544575"],"raw_result":"Some(\"1899414586654155\")","result_hash":"f78edd49720855dcf760533196a6a2efb03befb3278aa383a1ad7cb94ee636a1","slot":null},{"block":null,"method":"eth_call","params":["0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48","symbol()"],"raw_result":"Some(\"USDC\")","result_hash":"a3c9e246b0832b52e41efce041d8614251f5e288cdd4b192e85bfd3dfcb748ff","slot":null},{"block":null,"method":"eth_call","params":["0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48","decimals()"],"raw_result":"Some(6)","result_hash":"c68fe6989b1835302197d0af5be845dfab10ed9f9632205eb4ab5b949b9e1a6a","slot":null},{"block":null,"method":"eth_call","params":["0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48","balanceOf","0xAfdd3BdC20A31652e48b56B73952Ca324f544575"],"raw_result":"Some(\"21410145\")","result_hash":"c44ab6799e005af5db143e102818fbdf0eab84cf9835b2e157342c934d43ca4e","slot":null},{"block":null,"method":"eth_call","params":["0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48","symbol()"],"raw_result":"Some(\"USDC\")","result_hash":"a3c9e246b0832b52e41efce041d8614251f5e288cdd4b192e85bfd3dfcb748ff","slot":null},{"block":null,"method":"eth_call","params":["0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48","name()"],"raw_result":"Some(\"USD Coin\")","result_hash":"fe94af15dc887a2c9df1fb0d6d276e6c586ca9d430ffeac0d05e4baee0637fd1","slot":null},{"block":null,"method":"eth_call","params":["0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48","decimals()"],"raw_result":"Some(6)","result_hash":"c68fe6989b1835302197d0af5be845dfab10ed9f9632205eb4ab5b949b9e1a6a","slot":null},{"block":null,"method":"eth_call","params":["0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48","totalSupply()"],"raw_result":"Some(\"47909650227726635\")","result_hash":"68b596269b030ba4c809e7ca6b183121cbbc0ee9ee93adc74cbd61b8de2ad23e","slot":null},{"block":null,"method":"eth_call","params":["0x90A2a4c76b5D8c0bc892A69EA28Aa775a8f2dD48","symbol()"],"raw_result":"Some(\"SPYx\")","result_hash":"de41d2c14fa73c8e3ea34e4093b99a9165ac26bef56a7d98b711bdb990d48466","slot":null},{"block":null,"method":"eth_call","params":["0x90A2a4c76b5D8c0bc892A69EA28Aa775a8f2dD48","name()"],"raw_result":"Some(\"SP500 xStock\")","result_hash":"79ea6335245c40c23594121bcd21ed9b06c5de3e2a3ad3ae9b0b706bd912711d","slot":null},{"block":null,"method":"eth_call","params":["0x90A2a4c76b5D8c0bc892A69EA28Aa775a8f2dD48","decimals()"],"raw_result":"Some(18)","result_hash":"c14f173ff30df32f36fac2ea29d9a20482082428fd32b58be5433d310884f764","slot":null},{"block":null,"method":"eth_call","params":["0x90A2a4c76b5D8c0bc892A69EA28Aa775a8f2dD48","totalSupply()"],"raw_result":"Some(\"30151354243335401773820\")","result_hash":"356a3f04c2ff8eeb3fd17bc573caf03fb6ca67331d8b483ae4d2d8b8a45641e6","slot":null},{"block":null,"method":"eth_getCode","params":["0x90A2a4c76b5D8c0bc892A69EA28Aa775a8f2dD48","latest"],"result_hash":"71ee049d0c0cab5d785d7aef2e6b591e511475fb8ef465f4d8f5335bfd412bfd","slot":null},{"block":null,"method":"eth_getCode","params":["0x90A2a4c76b5D8c0bc892A69EA28Aa775a8f2dD48","latest"],"result_hash":"71ee049d0c0cab5d785d7aef2e6b591e511475fb8ef465f4d8f5335bfd412bfd","slot":null}],"registry_entry":{"chain":"ethereum","contract":"0x90A2a4c76b5D8c0bc892A69EA28Aa775a8f2dD48","decimals":null,"issuer":"Backed xStocks","last_checked":"2026-10-21T11:40:19Z","name":"SP500","official_deployments":[{"address":"0x90a2a4c76b5d8c0bc892a69ea28aa775a8f2dd48","network":"Ethereum","wrapper_address":"0xc88fcd8b874fdb3256e8b55b3decb8c24eab4c02","wrapper_address_v2":"0xe7e553cd128f0011777323a0b44a7b96ea1cb540"},{"address":"0x90a2a4c76b5d8c0bc892a69ea28aa775a8f2dd48","network":"BinanceSmartChain","wrapper_address":"0xc88fcd8b874fdb3256e8b55b3decb8c24eab4c02","wrapper_address_v2":"0xe7e553cd128f0011777323a0b44a7b96ea1cb540"},{"address":"0x90a2a4c76b5d8c0bc892a69ea28aa775a8f2dd48","network":"Arbitrum","wrapper_address":"0xc88fcd8b874fdb3256e8b55b3decb8c24eab4c02","wrapper_address_v2":"0xe7e553cd128f0011777323a0b44a7b96ea1cb540"},{"address":"XsoCS1TfEyfFhfvj8EtZ528L3CaKBDBRqRapnBbDF2W","network":"Solana"},{"address":"TKN6A3wSWHdZGanW5wBFkeFq2Yw3rhGqNz","network":"Tron"},{"address":"EQB1fyBAA9qQDP6LEGaF3cbU-Xbr-p6ESBZGnqlHkHIHAJZv","network":"Ton"},{"address":"0x90a2a4c76b5d8c0bc892a69ea28aa775a8f2dd48","network":"Mantle","wrapper_address":"0xc88fcd8b874fdb3256e8b55b3decb8c24eab4c02","wrapper_address_v2":"0xe7e553cd128f0011777323a0b44a7b96ea1cb540"},{"address":"0x90a2a4c76b5d8c0bc892a69ea28aa775a8f2dd48","network":"HyperEVM","wrapper_address_v2":"0xe7e553cd128f0011777323a0b44a7b96ea1cb540"},{"address":"0x90a2a4c76b5d8c0bc892a69ea28aa775a8f2dd48","network":"Ink","wrapper_address":"0xc88fcd8b874fdb3256e8b55b3decb8c24eab4c02","wrapper_address_v2":"0xe7e553cd128f0011777323a0b44a7b96ea1cb540"},{"address":"0x90a2a4c76b5d8c0bc892a69ea28aa775a8f2dd48","network":"XLayer","wrapper_address_v2":"0xe7e553cd128f0011777323a0b44a7b96ea1cb540"},{"address":"0x90a2a4c76b5d8c0bc892a69ea28aa775a8f2dd48","network":"Optimism","wrapper_address_v2":"0xe7e553cd128f0011777323a0b44a7b96ea1cb540"},{"address":"0x90a2a4c76b5d8c0bc892a69ea28aa775a8f2dd48","network":"Monad","wrapper_address_v2":"0xe7e553cd128f0011777323a0b44a7b96ea1cb540"}],"source":"xstocks-api","source_url":"https://api.xstocks.fi/api/v2/public/assets","ticker":"SPY"},"registry_hash":"93152e39c695658a34c9bda84906234fcad15c3b04c297499cf30850c38509bd","signer":"GJWKkiUd3zj1pJGfeE7JitiPiwDJC6XmNFvpJWJuvvpn","slot":null,"subject":"0xAfdd3BdC20A31652e48b56B73952Ca324f544575","ticker":"SPY","verdict":{"Verified":{"issuer":"Backed xStocks","ticker":"SPY"}},"version":1}

Signature

tEv7BYHq4dfIaF4MOy/3wrokwHv0X6IFK8ZITE/3GM1YQYa/kjsoLabTVBqyG5S9SZ9rwpmDrvEbr/Y35UXsCQ==

API call

GET /api/attest/a7fc802bc5aed3728d605e04ac1861bb561c35bb5eef0a077a0bf01bed2a6452

1. Fetch the public key and attestation JSON, then verify the signature with the published key.
2. Canonicalize the payload with sorted object keys and no whitespace, then verify its SHA-256 attestation id.
3. Run the API call above and compare the returned payload, serial, signer, and signature with this certificate.