Does QQQx / 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":26241025,"chain":"ethereum","checked_at":"2026-10-21T12:38:49Z","dev":false,"expires_at":"2026-10-22T12:38:49Z","issuer":"Backed xStocks","pool":{"base":{"address":"0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48","balance":"206149559","decimals":6,"symbol":"USDC"},"chain":"ethereum","dex":"uniswap-v4","pool":"0xb70ecb349e3002aadfdb3735a8904b6bdcb4d8207d1a724189bbc2ca3972eaec","quote":{"address":"0xa753A7395cAe905Cd615Da0B82A53E0560f250af","balance":"259767947141894001","decimals":18,"symbol":"QQQx"}},"quote_share_of_supply":7.619853957156122e-6,"reads":[{"block":null,"method":"eth_call","params":["0xbd216513d74c8cf14cf4747e6aaa6420ff64ee9e","poolKeys","0xb70ecb349e3002aadfdb3735a8904b6bdcb4d8207d1a724189"],"raw_result":"Object {\"currency0\": String(\"0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48\"), \"currency1\": String(\"0xa753a7395cae905cd615da0b82a53e0560f250af\"), \"fee\": String(\"870000\"), \"hooks\": String(\"0x0000000000000000000000000000000000000000\"), \"tickSpacing\": String(\"17400\")}","result_hash":"725ee1cc5a4c761dd0e7b59e7f09bb68205677026cf07631104b013b62019a75","slot":null},{"block":null,"method":"eth_call","params":["0x7ffe42c4a5deea5b0fec41c94c136cf115597227","getSlot0","0xb70ecb349e3002aadfdb3735a8904b6bdcb4d8207d1a724189bbc2ca3972eaec"],"raw_result":"true","result_hash":"18d10c7d2b4b04aaf04254d1ae5d655a5dc0407cbcdd5a8c3986e985370f36ee","slot":null},{"block":null,"method":"eth_call","params":["0x7ffe42c4a5deea5b0fec41c94c136cf115597227","getLiquidity","0xb70ecb349e3002aadfdb3735a8904b6bdcb4d8207d1a724189bbc2ca3972eaec"],"raw_result":"7317858156961","result_hash":"c2f9cc030882057245a948d0b9b416d825d6bcdbea2e5d2e0d40b4caadc14c4c","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":["0xa753A7395cAe905Cd615Da0B82A53E0560f250af","symbol()"],"raw_result":"Some(\"QQQx\")","result_hash":"2c713a19427f958927619283ac4869da02f72d63a16262a574b28fb477bbd534","slot":null},{"block":null,"method":"eth_call","params":["0xa753A7395cAe905Cd615Da0B82A53E0560f250af","decimals()"],"raw_result":"Some(18)","result_hash":"c14f173ff30df32f36fac2ea29d9a20482082428fd32b58be5433d310884f764","slot":null},{"block":26241025,"method":"eth_blockNumber","params":[],"result_hash":"db27bf2b066a5616dc7fabc66a1fbdb1b6f13307fdae2400e881370913f62a14","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(\"47909608209800303\")","result_hash":"b112f06216e281e47e29b53da678279426ffb51c32a4410c467c733985a65c96","slot":null},{"block":null,"method":"eth_call","params":["0xa753A7395cAe905Cd615Da0B82A53E0560f250af","symbol()"],"raw_result":"Some(\"QQQx\")","result_hash":"2c713a19427f958927619283ac4869da02f72d63a16262a574b28fb477bbd534","slot":null},{"block":null,"method":"eth_call","params":["0xa753A7395cAe905Cd615Da0B82A53E0560f250af","name()"],"raw_result":"Some(\"Nasdaq xStock\")","result_hash":"2e41f70b7eac5ea92fdac220a759df4bed77725a06f74e36a9a74236e4f4522b","slot":null},{"block":null,"method":"eth_call","params":["0xa753A7395cAe905Cd615Da0B82A53E0560f250af","decimals()"],"raw_result":"Some(18)","result_hash":"c14f173ff30df32f36fac2ea29d9a20482082428fd32b58be5433d310884f764","slot":null},{"block":null,"method":"eth_call","params":["0xa753A7395cAe905Cd615Da0B82A53E0560f250af","totalSupply()"],"raw_result":"Some(\"34090935154726307822415\")","result_hash":"dc8abd30095191a0fcaf78ec2287d0704c9c9df0129a208eaa09bf790c8456e7","slot":null},{"block":null,"method":"eth_getCode","params":["0xa753A7395cAe905Cd615Da0B82A53E0560f250af","latest"],"result_hash":"71ee049d0c0cab5d785d7aef2e6b591e511475fb8ef465f4d8f5335bfd412bfd","slot":null},{"block":null,"method":"eth_getCode","params":["0xa753A7395cAe905Cd615Da0B82A53E0560f250af","latest"],"result_hash":"71ee049d0c0cab5d785d7aef2e6b591e511475fb8ef465f4d8f5335bfd412bfd","slot":null}],"registry_entry":{"chain":"ethereum","contract":"0xa753A7395cAe905Cd615Da0B82A53E0560f250af","decimals":null,"issuer":"Backed xStocks","last_checked":"2026-10-21T11:40:19Z","name":"Nasdaq","official_deployments":[{"address":"0xa753a7395cae905cd615da0b82a53e0560f250af","network":"Ethereum","wrapper_address":"0xdbd9232fee15351068fe02f0683146e16d9f2cea","wrapper_address_v2":"0x4c1ae29c159838fc1b224636e28e086eb69101f7"},{"address":"0xa753a7395cae905cd615da0b82a53e0560f250af","network":"BinanceSmartChain","wrapper_address":"0xdbd9232fee15351068fe02f0683146e16d9f2cea","wrapper_address_v2":"0x4c1ae29c159838fc1b224636e28e086eb69101f7"},{"address":"0xa753a7395cae905cd615da0b82a53e0560f250af","network":"Arbitrum","wrapper_address":"0xdbd9232fee15351068fe02f0683146e16d9f2cea","wrapper_address_v2":"0x4c1ae29c159838fc1b224636e28e086eb69101f7"},{"address":"Xs8S1uUs1zvS2p7iwtsG3b6fkhpvmwz4GYU3gWAmWHZ","network":"Solana"},{"address":"TVBbuZ4hUisCPSsrR46BCQHDGtsBNAMjVh","network":"Tron"},{"address":"EQCe6utwqROmrO_cOUUvVNYkvyecUjfugtugvhUwlVYSEm7x","network":"Ton"},{"address":"0xa753a7395cae905cd615da0b82a53e0560f250af","network":"Mantle","wrapper_address":"0xdbd9232fee15351068fe02f0683146e16d9f2cea","wrapper_address_v2":"0x4c1ae29c159838fc1b224636e28e086eb69101f7"},{"address":"0xa753a7395cae905cd615da0b82a53e0560f250af","network":"HyperEVM","wrapper_address_v2":"0x4c1ae29c159838fc1b224636e28e086eb69101f7"},{"address":"0xa753a7395cae905cd615da0b82a53e0560f250af","network":"Ink","wrapper_address":"0xdbd9232fee15351068fe02f0683146e16d9f2cea","wrapper_address_v2":"0x4c1ae29c159838fc1b224636e28e086eb69101f7"},{"address":"0xa753a7395cae905cd615da0b82a53e0560f250af","network":"XLayer","wrapper_address_v2":"0x4c1ae29c159838fc1b224636e28e086eb69101f7"},{"address":"0xa753a7395cae905cd615da0b82a53e0560f250af","network":"Optimism","wrapper_address_v2":"0x4c1ae29c159838fc1b224636e28e086eb69101f7"},{"address":"0xa753a7395cae905cd615da0b82a53e0560f250af","network":"Monad","wrapper_address_v2":"0x4c1ae29c159838fc1b224636e28e086eb69101f7"}],"source":"xstocks-api","source_url":"https://api.xstocks.fi/api/v2/public/assets","ticker":"QQQ"},"registry_hash":"93152e39c695658a34c9bda84906234fcad15c3b04c297499cf30850c38509bd","signer":"GJWKkiUd3zj1pJGfeE7JitiPiwDJC6XmNFvpJWJuvvpn","slot":null,"subject":"0xb70ecb349e3002aadfdb3735a8904b6bdcb4d8207d1a724189bbc2ca3972eaec","ticker":"QQQ","verdict":{"Verified":{"issuer":"Backed xStocks","ticker":"QQQ"}},"version":1}

Signature

sINqpZdsaYDjGnZTFiPstBMqZzjD9K2Rn9diescy+PrtJ2MyBgMXIk9WCeMjoHCVDng7gUPxPuZVgF2LEsZLBw==

API call

GET /api/attest/517443ed2a39c8ac89851e6c697f1e6c0d7ba57318a2a2302ce5b872a390e5d0

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.