Signing

Cardano data signatures are commonly used for login authentication, address ownership proof, and off-chain authorization. UKey Wallet returns a COSE format signature and public key via CIP-8.

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Signature data (CIP-8)

The following example converts the message into a hexadecimal payload and then requests the user's signature:

const api = await window.cardano.ukey.enable();

const addresses = await api.getUsedAddresses();
const address = addresses[0];

// Note: message to sign
const payload = Buffer.from("Cardano demo message").toString("hex");

const signature = await api.signData(address, payload);

console.log({
  signature: signature.signature, // COSE_Sign1 signature
  key: signature.key, // COSE_Key 格式的公钥
});

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Verification

import { COSESign1, COSEKey } from "@emurgo/cardano-message-signing-browser";

const coseSign1 = COSESign1.from_bytes(Buffer.from(signature.signature, "hex"));
const coseKey = COSEKey.from_bytes(Buffer.from(signature.key, "hex"));

// Retrieve signed payload
const signedPayload = coseSign1.payload();

// Validate signature
const publicKey = coseKey.header(0); // Retrieve the Ed25519 key
// place your validation logic here

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Handle Errors

try {
  const api = await window.cardano.ukey.enable();
} catch (error) {
  if (error.code === -1) {
    console.log("The user declined the connection");
  } else if (error.code === -2) {
    console.log("No account was returned");
  } else {
    console.error("Operation error:", error.message);
  }
}

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Top Errors

Code	Details
-1	User rejected the request
-2	Account could not be found
-3	Network selection is invalid