Two Predge signed records, notarized on Base

// Node 18+, no packages: node predge_check.mjs 5369848
import { createHash, createPublicKey, verify } from "node:crypto";
const id = process.argv[2] ?? "5369848";
const env = (await (await fetch(`https://api.predge.io/v1/settlement-risk/${id}`)).json()).attestation;
const keys = (await (await fetch("https://api.predge.io/.well-known/predge-keys.json")).json()).keys;
const hash = createHash("sha256").update(env.canonical, "utf8").digest("hex");
const pub = createPublicKey({ format: "der", type: "spki",
  key: Buffer.concat([Buffer.from("302a300506032b6570032100", "hex"), Buffer.from(env.public_key, "hex")]) });
console.log("sha256(canonical)          ", hash);
console.log("matches content_hash       ", hash === env.content_hash);
console.log("ed25519 signature valid    ", verify(null, Buffer.from(env.canonical, "utf8"), pub, Buffer.from(env.signature, "hex")));
console.log("key listed, active, kid ok ", keys.some(k => k.active && k.kid === "13fa3d18a369e6c7" && k.public_key === env.public_key));

# Python 3.8+, needs `pip install cryptography`: python3 predge_check.py 5369848
import hashlib, json, sys, urllib.request
from cryptography.hazmat.primitives.asymmetric.ed25519 import Ed25519PublicKey

get = lambda url: json.load(urllib.request.urlopen(url, timeout=20))
mid = sys.argv[1] if len(sys.argv) > 1 else "5369848"
env = get(f"https://api.predge.io/v1/settlement-risk/{mid}")["attestation"]
keys = get("https://api.predge.io/.well-known/predge-keys.json")["keys"]
canon = env["canonical"].encode("utf-8")
digest = hashlib.sha256(canon).hexdigest()
print("sha256(canonical)          ", digest)
print("matches content_hash       ", digest == env["content_hash"])
Ed25519PublicKey.from_public_bytes(bytes.fromhex(env["public_key"])).verify(bytes.fromhex(env["signature"]), canon)
print("ed25519 signature valid     True")  # verify() raises InvalidSignature otherwise
print("key listed, active, kid ok ", any(k["active"] and k["kid"] == "13fa3d18a369e6c7" and k["public_key"] == env["public_key"] for k in keys))

# Python 3.8+, standard library only: python3 fairseal_check.py nr_2e090e4c78df92765ea0b600f298c8dc
import hashlib, json, sys, time, urllib.request

RPC = "https://mainnet.base.org"   # any public Base mainnet RPC works
CONTRACT = "0xee09671bbc6b932bf1461caff360bfdd9bea55ca"
EXPECTED = {  # the payload hashes listed on this page
    "nr_2e090e4c78df92765ea0b600f298c8dc": "d65f90881964b342c3de964b6ee3e6751417229ef4c2d96ee1cb8bf7d792320c",
    "nr_6f99fa85e571dc8e766d014a9da49440": "11a2bf5505b6d25c3b04c8c0049ba837b6097061d19574e27e44526dd57cf5e2",
}
sha = lambda s: hashlib.sha256(s.encode()).hexdigest()   # inputs are hex strings, hashed as text

def rpc(method, *params):
    body = json.dumps({"jsonrpc": "2.0", "id": 1, "method": method, "params": list(params)}).encode()
    req = urllib.request.Request(RPC, body, {"Content-Type": "application/json", "User-Agent": "verify"})
    return json.load(urllib.request.urlopen(req, timeout=20))["result"]

rid = sys.argv[1] if len(sys.argv) > 1 else "nr_2e090e4c78df92765ea0b600f298c8dc"
r = json.load(urllib.request.urlopen(f"https://api.fairseal.io/v1/notarize/{rid}", timeout=20))
p = r["proof"]
node = leaf = sha(rid + "||" + r["payload_hash"])
for sib in p["merkle_path"]:
    node = sha(min(node, sib) + max(node, sib))
tx = rpc("eth_getTransactionByHash", p["anchor_tx"])
ok = rpc("eth_getTransactionReceipt", p["anchor_tx"])["status"] == "0x1"
ts = int(rpc("eth_getBlockByNumber", tx["blockNumber"], False)["timestamp"], 16)
print("payload_hash as listed here ", r["payload_hash"] == EXPECTED.get(rid))
print("leaf recomputed             ", leaf == p["leaf_hash"])
print("root recomputed             ", node == p["merkle_root"], node[:16] + "...")
print("tx to FairSeal contract, ok ", tx["to"].lower() == CONTRACT and ok)
print("root in tx calldata         ", node in tx["input"].lower())
print("anchored in block", int(tx["blockNumber"], 16), "at", time.strftime("%Y-%m-%dT%H:%M:%SZ", time.gmtime(ts)))