8R8CrCdf

1public static void main(String[] args) throws NoSuchAlgorithmException, InvalidKeyException {
2   
3        String header = "{\"alg\":\"HS256\",\"typ\":\"JWT\"}";
4        String payload = "{\"sub\":\"1234567890\",\"name\":\"John Doe\",\"iat\":1516239022}";
5        
6        String headerBase64 = Base64.encodeBase64URLSafeString(header.getBytes());
7        String payloadBase64 = Base64.encodeBase64URLSafeString(payload.getBytes());
8       
9        //Create a secret to create the signature
10        String secret = "your-256-bit-secret"; //this could be anything
11        final SecretKeySpec secret_key = new javax.crypto.spec.SecretKeySpec(StandardCharsets.UTF_8.encode(secret).array(), "HmacSHA256");
12   
13        //Create the signature
14        final Mac mac = Mac.getInstance("HmacSHA256");
15        mac.init(secret_key);
16        mac.update(headerBase64.getBytes());
17        mac.update((byte)'.');
18        byte[] bytes = mac.doFinal(payloadBase64.getBytes());
19   
20        //print
21        System.out.println(headerBase64);
22        System.out.println(payloadBase64);
23        System.out.println(Base64.encodeBase64URLSafeString(bytes));
24
25    }