java hmac ssh256

   public String encode() throws NoSuchAlgorithmException, InvalidKeyException{

    SecretKey secretKey= new SecretKeySpec("abc".getBytes(), "HmacSHA256");  

    Mac mac=Mac.getInstance(secretKey.getAlgorithm());  

    mac.init(secretKey); 

    String str = "hello world";

       return convertToHex( mac.doFinal(str.getBytes()));

    }

    

private  String convertToHex(byte[] data)

{

StringBuffer buf = new StringBuffer();

for (int i = 0; i < data.length; i++)

{

int halfbyte = (data[i] >>> 4) & 0x0F;

int two_halfs = 0;

do

{

if ((0 <= halfbyte) && (halfbyte <= 9))

buf.append((char) ('0' + halfbyte));

else

buf.append((char) ('a' + (halfbyte - 10)));

halfbyte = data[i] & 0x0F;

}

while (two_halfs++ < 1);

}

return buf.toString();

}