code: public static String hashString(String input, int length) {
  		MessageDigest md;
  		try {
  			md = MessageDigest.getInstance("SHA");
  		} catch (NoSuchAlgorithmException e) {
  			throw new IllegalArgumentException("The SHA Algorithm could not be found", e);
  		}
  		byte[] bytes = input.getBytes();
  		md.update(bytes);
  		String hashed =  convertToHex(md.digest());
  		hashed = reduceHash(hashed, length);
  		return hashed;
  	}
docs: Compute hash value of a string
  
  @param input
  @return