https://github.com/abhilshit/bookstore 

	http://localhost:8080/bookstore

1. HTTP BASIC Authentication
2. Custom Token Based Authentication v 1.0
3. Custom Token Based Authentication v 2.0
4. Custom Token Based Authentication v 3.0

public static void customeAuthV3Client() throws Exception {
	CloseableHttpClient httpClient = HttpClientBuilder.create().build();

	HttpPost httpPostAuth = new HttpPost("http://localhost:8080/bookstore/api/auth/v3");
	HttpPost httpPostToken = new HttpPost("http://localhost:8080/bookstore/api/auth/v3/token");

	HttpGet httpget = new HttpGet("http://localhost:8080/bookstore/api/v3/books/1");
	String apiKey = "egEmfIwA6dyFmHoKjjjsQw==";

	httpPostAuth.addHeader("-x-api-user", "user1");

	CloseableHttpResponse response = httpClient.execute(httpPostAuth);
	HttpEntity entity = response.getEntity();

	System.out.println("----------------------------------------");
	System.out.println(response.getStatusLine());
	if (entity != null) {
		System.out.println(EntityUtils.toString(entity, "UTF-8"));
	}
	byte[] challenge = Base64.decodeBase64(response.getFirstHeader("-x-challenge").getValue());
	System.out.println("challenge obtained: " + response.getFirstHeader("-x-challenge").getValue());

	Cipher c = Cipher.getInstance("AES");
	SecretKeySpec k = new SecretKeySpec(Base64.decodeBase64(apiKey.getBytes()), "AES");

	c.init(Cipher.DECRYPT_MODE, k);
	byte[] decryptedData = c.doFinal(challenge);
	String answer = new String(decryptedData);

	httpPostToken.addHeader("-x-challenge-answer", answer);
	httpPostToken.addHeader("-x-api-user", "user1");

	response = httpClient.execute(httpPostToken);
	entity = response.getEntity();

	System.out.println("----------------------------------------");
	System.out.println(response.getStatusLine());
	if (entity != null) {
		System.out.println(EntityUtils.toString(entity, "UTF-8"));
	}
	String access_token = response.getFirstHeader("-x-access-token").getValue();
	System.out.println("access token obtained : " + access_token);

	// use the access_token for next calls till it expires

	EntityUtils.consume(entity);

	httpget.addHeader("-x-access-token", access_token);
	ZonedDateTime now = ZonedDateTime.now(ZoneOffset.UTC);
	long currentTime = now.toInstant().toEpochMilli();
	httpget.addHeader("-x-timestamp", currentTime+"");
	httpget.addHeader("-x-nonce", UUID.randomUUID().toString());
	
	HashMap<String, String> headerMap = new HashMap<>();
	
	for(Header header:httpget.getAllHeaders()){
		headerMap.put(header.getName(),header.getValue());
	}
	
	httpget.addHeader("-x-signature", HashingUtil.generateSignature(apiKey, httpget.getURI().toURL().toString(), "", 		httpget.getMethod(), headerMap));
	response = httpClient.execute(httpget);
	entity = response.getEntity();

	System.out.println("----------------------------------------");
	System.out.println(response.getStatusLine());
	if (entity != null) {
		System.out.println(EntityUtils.toString(entity, "UTF-8"));
	}
	EntityUtils.consume(entity);
}