create JWT using EC private key

[willyprayogo26]

I generate private key using this command:
openssl ecparam -out private.key -name secp521r1 -genkey

but I cannot import EC private key to use in:

    const keyFile = fs.readFileSync('./private.key')
    const ecPrivateKey = await jose.importPKCS8(keyFile.toString(), 'ES256')

    const payload = {
          sub: xxx,
          aud: xxx',
          iss: xxx,
          iat: Date.now(),
          exp: 120
    }
    await new jose.SignJWT(payload)
          .setProtectedHeader({ alg: 'ES256', typ: 'JWT', kid: 'xxxx' })
          .sign(ecPrivateKey)

could u help me how to solve this?
thanks

[panva]

1. your private.key file does not just contain the PKCS#8 envelope that importPKCS8 expects. It has other content in it that's not expected.
2. secp521r1 is not usable with the ES256 JWS Algorithm. The algorithm name for secp521r1 curve EC key would ES512. see Algorithm Key Requirements #210

[willyprayogo26]

ok I just tried to use ES512, but still got an error:

ERROR [ExceptionsHandler] "pkcs8" must be PCKS8 formatted string

so how to solve this?

[panva]

see 1) your key is SEC1, not PKCS8