Read RSA Private Key from String

Read RSA Private Key from String

private RSAPrivateKey readPrivateKey() throws Exception {
        BufferedReader rdr = new BufferedReader(new StringReader(privateKeyString));
        String pkcs8Pem = rdr.lines().collect(Collectors.joining());
        pkcs8Pem = pkcs8Pem
                .replace("-----BEGIN PRIVATE KEY-----", "")
                .replace("-----END PRIVATE KEY-----", "")
                .replaceAll("\\s+", "");

        byte[] pkcs8EncodedBytes = Base64.decode(pkcs8Pem);

        PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(pkcs8EncodedBytes);
        KeyFactory kf = KeyFactory.getInstance("RSA");
        PrivateKey privKey = kf.generatePrivate(keySpec);
        return (RSAPrivateKey) privKey;
    }