--- /dev/null
+package iotcloud;
+import java.io.*;
+import java.net.*;
+import java.util.Arrays;
+import javax.crypto.*;
+import javax.crypto.spec.*;
+import java.security.SecureRandom;
+
+/**
+ * This class provides a communication API to the webserver. It also
+ * validates the HMACs on the slots and handles encryption.
+ * @author Brian Demsky <bdemsky@uci.edu>
+ * @version 1.0
+ */
+
+
+class CloudComm {
+ String baseurl;
+ Cipher encryptCipher;
+ Cipher decryptCipher;
+ Mac mac;
+ String password;
+ SecureRandom random;
+ static final int SALT_SIZE = 8;
+ byte salt[];
+ Table table;
+
+ /**
+ * Empty Constructor needed for child class.
+ */
+
+ CloudComm() {
+ }
+
+ /**
+ * Constructor for actual use. Takes in the url and password.
+ */
+
+ CloudComm(Table _table, String _baseurl, String _password) {
+ this.table=_table;
+ this.baseurl=_baseurl;
+ this.password = _password;
+ this.random = new SecureRandom();
+ }
+
+ /**
+ * Generates Key from password.
+ */
+
+ private SecretKeySpec initKey() {
+ try {
+ PBEKeySpec keyspec = new PBEKeySpec(password.toCharArray(), salt, 65536, 128);
+ SecretKey tmpkey = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA256").generateSecret(keyspec);
+ return new SecretKeySpec(tmpkey.getEncoded(), "AES");
+ } catch (Exception e) {
+ e.printStackTrace();
+ throw new Error("Failed generating key.");
+ }
+ }
+
+ /**
+ * Inits the HMAC generator.
+ */
+
+ private void initCrypt() {
+ try {
+ SecretKeySpec key=initKey();
+ password = null; // drop password
+ mac = Mac.getInstance("HmacSHA256");
+ mac.init(key);
+ encryptCipher =Cipher.getInstance("AES/ECB/PKCS5Padding");
+ encryptCipher.init(Cipher.ENCRYPT_MODE, key);
+ decryptCipher =Cipher.getInstance("AES/ECB/PKCS5Padding");
+ decryptCipher.init(Cipher.DECRYPT_MODE, key);
+ } catch (Exception e) {
+ e.printStackTrace();
+ throw new Error("Failed To Initialize Ciphers");
+ }
+ }
+
+ /*
+ * Builds the URL for the given request.
+ */
+
+ private URL buildRequest(boolean isput, long sequencenumber, long maxentries) throws IOException {
+ String reqstring=isput?"req=putslot":"req=getslot";
+ String urlstr=baseurl+"?"+reqstring+"&seq="+sequencenumber;
+ if (maxentries != 0)
+ urlstr += "&max="+maxentries;
+ return new URL(urlstr);
+ }
+
+ public void setSalt() {
+ try {
+ salt = new byte[SALT_SIZE];
+ random.nextBytes(salt);
+ URL url=new URL(baseurl+"?req=setsalt");
+ URLConnection con=url.openConnection();
+ HttpURLConnection http = (HttpURLConnection) con;
+ http.setRequestMethod("POST");
+ http.setFixedLengthStreamingMode(salt.length);
+ http.setDoOutput(true);
+ http.connect();
+ OutputStream os=http.getOutputStream();
+ os.write(salt);
+ int responsecode=http.getResponseCode();
+ if (responsecode != HttpURLConnection.HTTP_OK)
+ throw new Error("Invalid response");
+ } catch (Exception e) {
+ e.printStackTrace();
+ throw new Error("Failed setting salt");
+ }
+ initCrypt();
+ }
+
+ private void getSalt() throws Exception {
+ URL url=new URL(baseurl+"?req=getsalt");
+ URLConnection con=url.openConnection();
+ HttpURLConnection http = (HttpURLConnection) con;
+ http.setRequestMethod("POST");
+ http.connect();
+
+ InputStream is=http.getInputStream();
+ DataInputStream dis=new DataInputStream(is);
+ int salt_length=dis.readInt();
+ byte [] tmp=new byte[salt_length];
+ dis.readFully(tmp);
+ salt=tmp;
+ }
+
+ /*
+ * API for putting a slot into the queue. Returns null on success.
+ * On failure, the server will send slots with newer sequence
+ * numbers.
+ */
+
+ Slot[] putSlot(Slot slot, int max) {
+ try {
+ if (salt == null) {
+ getSalt();
+ initCrypt();
+ }
+
+ long sequencenumber=slot.getSequenceNumber();
+ byte[] bytes=slot.encode(mac);
+ bytes = encryptCipher.doFinal(bytes);
+
+ URL url=buildRequest(true, sequencenumber, max);
+ URLConnection con=url.openConnection();
+ HttpURLConnection http = (HttpURLConnection) con;
+
+ http.setRequestMethod("POST");
+ http.setFixedLengthStreamingMode(bytes.length);
+ http.setDoOutput(true);
+ http.connect();
+
+ OutputStream os=http.getOutputStream();
+ os.write(bytes);
+
+ InputStream is=http.getInputStream();
+ DataInputStream dis=new DataInputStream(is);
+ byte[] resptype=new byte[7];
+ dis.readFully(resptype);
+ if (Arrays.equals(resptype, "getslot".getBytes()))
+ return processSlots(dis);
+ else if (Arrays.equals(resptype, "putslot".getBytes()))
+ return null;
+ else
+ throw new Error("Bad response to putslot");
+ } catch (Exception e) {
+ e.printStackTrace();
+ throw new Error("putSlot failed");
+ }
+ }
+
+ /**
+ * Request the server to send all slots with the given
+ * sequencenumber or newer.
+ */
+
+ Slot[] getSlots(long sequencenumber) {
+ try {
+ if (salt == null) {
+ getSalt();
+ initCrypt();
+ }
+
+ URL url=buildRequest(false, sequencenumber, 0);
+ URLConnection con=url.openConnection();
+ HttpURLConnection http = (HttpURLConnection) con;
+ http.setRequestMethod("POST");
+ http.connect();
+ InputStream is=http.getInputStream();
+
+ DataInputStream dis=new DataInputStream(is);
+
+ byte[] resptype=new byte[7];
+ dis.readFully(resptype);
+ if (!Arrays.equals(resptype, "getslot".getBytes()))
+ throw new Error("Bad Response: "+new String(resptype));
+ else
+ return processSlots(dis);
+ } catch (Exception e) {
+ e.printStackTrace();
+ throw new Error("getSlots failed");
+ }
+ }
+
+ /**
+ * Method that actually handles building Slot objects from the
+ * server response. Shared by both putSlot and getSlots.
+ */
+
+ private Slot[] processSlots(DataInputStream dis) throws Exception {
+ int numberofslots=dis.readInt();
+ int[] sizesofslots=new int[numberofslots];
+ Slot[] slots=new Slot[numberofslots];
+ for(int i=0; i<numberofslots; i++)
+ sizesofslots[i]=dis.readInt();
+
+ for(int i=0; i<numberofslots; i++) {
+ byte[] data=new byte[sizesofslots[i]];
+ dis.readFully(data);
+
+ data = decryptCipher.doFinal(data);
+
+ slots[i]=Slot.decode(table, data, mac);
+ }
+ dis.close();
+ return slots;
+ }
+}
projects / iotcloud.git / blobdiff