Does CRCLx / 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":26259137,"chain":"ethereum","checked_at":"2026-10-24T01:13:15Z","dev":false,"expires_at":"2026-10-25T01:13:15Z","issuer":"Backed xStocks","pool":{"base":{"address":"0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48","balance":"9703754","decimals":6,"symbol":"USDC"},"chain":"ethereum","dex":"uniswap-v4","pool":"0xe81d7f1445d0f7d421e5968e044b01a14017e160ae6c92d45f5f18ca77595946","quote":{"address":"0xfEbDEd1B0986a8ee107f5AB1a1c5a813491DeCEB","balance":"101671701287584553","decimals":18,"symbol":"CRCLx"}},"quote_share_of_supply":2.2593711397241014e-7,"reads":[{"block":null,"method":"eth_call","params":["0xbd216513d74c8cf14cf4747e6aaa6420ff64ee9e","poolKeys","0xe81d7f1445d0f7d421e5968e044b01a14017e160ae6c92d45f"],"raw_result":"Object {\"currency0\": String(\"0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48\"), \"currency1\": String(\"0xfebded1b0986a8ee107f5ab1a1c5a813491deceb\"), \"fee\": String(\"3000\"), \"hooks\": String(\"0x0000000000000000000000000000000000000000\"), \"tickSpacing\": String(\"60\")}","result_hash":"55fd491fdeaa339bfa090a0069ce448713168c177a65088e3c981c498a82926c","slot":null},{"block":null,"method":"eth_call","params":["0x7ffe42c4a5deea5b0fec41c94c136cf115597227","getSlot0","0xe81d7f1445d0f7d421e5968e044b01a14017e160ae6c92d45f5f18ca77595946"],"raw_result":"true","result_hash":"18d10c7d2b4b04aaf04254d1ae5d655a5dc0407cbcdd5a8c3986e985370f36ee","slot":null},{"block":null,"method":"eth_call","params":["0x7ffe42c4a5deea5b0fec41c94c136cf115597227","getLiquidity","0xe81d7f1445d0f7d421e5968e044b01a14017e160ae6c92d45f5f18ca77595946"],"raw_result":"993276018110","result_hash":"bf690e631d1991b1885894e763c1d0e9dd602178923fab1c289995c9109a714b","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":["0xfEbDEd1B0986a8ee107f5AB1a1c5a813491DeCEB","symbol()"],"raw_result":"Some(\"CRCLx\")","result_hash":"e6b8a44b5ed71669fddfbadd69171449bc1af5981ce01d3ee09104646b895fea","slot":null},{"block":null,"method":"eth_call","params":["0xfEbDEd1B0986a8ee107f5AB1a1c5a813491DeCEB","decimals()"],"raw_result":"Some(18)","result_hash":"c14f173ff30df32f36fac2ea29d9a20482082428fd32b58be5433d310884f764","slot":null},{"block":26259137,"method":"eth_blockNumber","params":[],"result_hash":"e31147f53527b9dfce3857a1706eb6d4b7ffed4a48ac4efbe89d086b86f407b4","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(\"47790785318297484\")","result_hash":"e49a54d3a5c3ebf78fcba166493bbd349da2dd718e7800f308ac2a7706a08774","slot":null},{"block":null,"method":"eth_call","params":["0xfEbDEd1B0986a8ee107f5AB1a1c5a813491DeCEB","symbol()"],"raw_result":"Some(\"CRCLx\")","result_hash":"e6b8a44b5ed71669fddfbadd69171449bc1af5981ce01d3ee09104646b895fea","slot":null},{"block":null,"method":"eth_call","params":["0xfEbDEd1B0986a8ee107f5AB1a1c5a813491DeCEB","name()"],"raw_result":"Some(\"Circle xStock\")","result_hash":"a773d766a4cef1ad99105422276b716af516af2bf72b1e9ab1a92e09584351c7","slot":null},{"block":null,"method":"eth_call","params":["0xfEbDEd1B0986a8ee107f5AB1a1c5a813491DeCEB","decimals()"],"raw_result":"Some(18)","result_hash":"c14f173ff30df32f36fac2ea29d9a20482082428fd32b58be5433d310884f764","slot":null},{"block":null,"method":"eth_call","params":["0xfEbDEd1B0986a8ee107f5AB1a1c5a813491DeCEB","totalSupply()"],"raw_result":"Some(\"450000000000000000000000\")","result_hash":"cc55a915807eabd530e17404c185bbb5eb25af7ab11f63000176cf72f8127d2a","slot":null},{"block":null,"method":"eth_getCode","params":["0xfEbDEd1B0986a8ee107f5AB1a1c5a813491DeCEB","latest"],"result_hash":"71ee049d0c0cab5d785d7aef2e6b591e511475fb8ef465f4d8f5335bfd412bfd","slot":null},{"block":null,"method":"eth_getCode","params":["0xfEbDEd1B0986a8ee107f5AB1a1c5a813491DeCEB","latest"],"result_hash":"71ee049d0c0cab5d785d7aef2e6b591e511475fb8ef465f4d8f5335bfd412bfd","slot":null}],"registry_entry":{"chain":"ethereum","contract":"0xfEbDEd1B0986a8ee107f5AB1a1c5a813491DeCEB","decimals":null,"issuer":"Backed xStocks","last_checked":"2026-10-24T01:11:43Z","name":"Circle","official_deployments":[{"address":"0xfebded1b0986a8ee107f5ab1a1c5a813491deceb","network":"Ethereum","wrapper_address":"0xa90872aca656ebe47bdebf3b19ec9dd9c5adc7f8","wrapper_address_v2":"0xb11134f14d5b94db60d4599dfdc3bf1bba2150e8"},{"address":"0xfebded1b0986a8ee107f5ab1a1c5a813491deceb","network":"BinanceSmartChain","wrapper_address":"0xa90872aca656ebe47bdebf3b19ec9dd9c5adc7f8","wrapper_address_v2":"0xb11134f14d5b94db60d4599dfdc3bf1bba2150e8"},{"address":"0xfebded1b0986a8ee107f5ab1a1c5a813491deceb","network":"Arbitrum","wrapper_address":"0xa90872aca656ebe47bdebf3b19ec9dd9c5adc7f8","wrapper_address_v2":"0xb11134f14d5b94db60d4599dfdc3bf1bba2150e8"},{"address":"XsueG8BtpquVJX9LVLLEGuViXUungE6WmK5YZ3p3bd1","network":"Solana"},{"address":"TRXfha1owZvFk5ru7cmd5SXDX1uKtcCRJN","network":"Tron"},{"address":"EQB-RPtAAQeFSGW3gIj0zREh4N92MGXfqFzxAc6TRvu-zvYT","network":"Ton"},{"address":"0xfebded1b0986a8ee107f5ab1a1c5a813491deceb","network":"Mantle","wrapper_address":"0xa90872aca656ebe47bdebf3b19ec9dd9c5adc7f8","wrapper_address_v2":"0xb11134f14d5b94db60d4599dfdc3bf1bba2150e8"},{"address":"0xfebded1b0986a8ee107f5ab1a1c5a813491deceb","network":"HyperEVM","wrapper_address_v2":"0xb11134f14d5b94db60d4599dfdc3bf1bba2150e8"},{"address":"0xfebded1b0986a8ee107f5ab1a1c5a813491deceb","network":"Ink","wrapper_address_v2":"0xb11134f14d5b94db60d4599dfdc3bf1bba2150e8"},{"address":"0xfebded1b0986a8ee107f5ab1a1c5a813491deceb","network":"XLayer","wrapper_address_v2":"0xb11134f14d5b94db60d4599dfdc3bf1bba2150e8"},{"address":"0xfebded1b0986a8ee107f5ab1a1c5a813491deceb","network":"Optimism","wrapper_address_v2":"0xb11134f14d5b94db60d4599dfdc3bf1bba2150e8"},{"address":"0xfebded1b0986a8ee107f5ab1a1c5a813491deceb","network":"Monad","wrapper_address_v2":"0xb11134f14d5b94db60d4599dfdc3bf1bba2150e8"}],"source":"xstocks-api","source_url":"https://api.xstocks.fi/api/v2/public/assets","ticker":"CRCL"},"registry_hash":"85767b2b36b442fd2a8e647f3ecacaa1cfc2fa6d19f2c7035c8c7b7788fe40fd","signer":"GJWKkiUd3zj1pJGfeE7JitiPiwDJC6XmNFvpJWJuvvpn","slot":null,"subject":"0xe81d7f1445d0f7d421e5968e044b01a14017e160ae6c92d45f5f18ca77595946","ticker":"CRCL","verdict":{"Verified":{"issuer":"Backed xStocks","ticker":"CRCL"}},"version":1}

Signature

5yT9xffNk/L0IqP9WsbiALQ8FF7AOu3awOCdmRzJDzWnsFZrEarP2OfSun2bZXhcxdgyEatbcKl6JDInGGXpBA==

API call

GET /api/attest/27d915d3b114e3ac46c7862a3521519ae683f854ee3d0554ff3c97ba34eb3a5c

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.