如何用认知键生成rsapublicey

我需要生成一个公钥来验证来自Cognito的JWT令牌。这是钥匙:

{
  keys: [
    {
      alg: "RS256",
      e: "AQAB",
      kid: "7sbG73+G/8A+wPT4Vaf/+ttnBHuLZcjEmfiBXl3E8Fk=",
      kty: "RSA",
      n: "blablablablabla",
      use: "sig"
    },
    {
      alg: "RS256",
      e: "AQAB",
      kid: "Zbf1euSHNj4lXgXHIQwYZfERTdm1Rkeqrm1ppnpClRR=",
      kty: "RSA",
      n: "blablablablabla",
      use: "sig"
    }
  ]
}

我可以很容易地用来自Azure的X5C密钥创建它,但是我不能用Cognito来创建它。我应该使用哪个键来创建rsapublickey?

 CertificateFactory factory = CertificateFactory.getInstance("X.509");

//Creating a cert from x5c key   
X509Certificate cert = (X509Certificate) factory.generateCertificate(new ByteArrayInputStream(DatatypeConverter.parseBase64Binary(x5c)));

RSAPublicKey publicKey = (RSAPublicKey) cert.getPublicKey();
RSAPrivateKey privateKey = null;