instakey.java

package com.ilegendsoft.app;

import java.io.UnsupportedEncodingException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;

import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;

public class Main {

	private final static String PRIVATE_KEY = "b4a23f5e39b5929e0666ac5de94c89d1618a2916";
	private final static String MSG = "{\"username\":\"pindleskin8\",\"guid\":\"92a0491f-3663-47d3-ad12-147f8f7a5f63\",\"password\":\"shanghai13\",\"device_id\":\"android-1caa01e98bb5c6cb\"}";

	public static void main(String[] args) {
		System.out.println(hmacDigest(MSG, PRIVATE_KEY, "HmacSHA256"));
	}

	public static String hmacDigest(String msg, String keyString, String algo) {
		String digest = null;
		try {
			SecretKeySpec key = new SecretKeySpec(
					(keyString).getBytes("UTF-8"), algo);
			Mac mac = Mac.getInstance(algo);
			mac.init(key);

			byte[] bytes = mac.doFinal(msg.getBytes("ASCII"));

			StringBuffer hash = new StringBuffer();
			for (int i = 0; i < bytes.length; i++) {
				String hex = Integer.toHexString(0xFF & bytes[i]);
				if (hex.length() == 1) {
					hash.append('0');
				}
				hash.append(hex);
			}
			digest = hash.toString();
		} catch (UnsupportedEncodingException e) {
			e.printStackTrace();
		} catch (InvalidKeyException e) {
			e.printStackTrace();
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
		}
		return digest;
	}

}