src/java/iotcloud/Table.java

   1 package iotcloud;
   2 import java.util.HashMap;
   3 import java.util.Arrays;
   4 import javax.crypto.spec.*;
   5 import javax.crypto.*;
   6
   7 public class Table {
   8         int numslots;
   9         HashMap<IoTString, IoTString> table=new HashMap<IoTString, IoTString>();
  10         HashMap<Long, Long> lastmessage=new HashMap<Long, Long>();
  11         SlotBuffer buffer;
  12         CloudComm cloud;
  13         private Mac hmac;
  14         long sequencenumber;
  15         long machineid;
  16
  17         public Table(String baseurl, String password, long _machineid) {
  18                 machineid=_machineid;
  19                 buffer = new SlotBuffer();
  20                 sequencenumber = 1;
  21                 initCloud(baseurl, password);
  22         }
  23
  24         private void initCloud(String baseurl, String password) {
  25                 try {
  26                         SecretKeySpec secret=getKey(password);
  27                         Cipher encryptCipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
  28                         encryptCipher.init(Cipher.ENCRYPT_MODE, secret);
  29                         Cipher decryptCipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
  30                         decryptCipher.init(Cipher.DECRYPT_MODE, secret);
  31                         hmac = Mac.getInstance("HmacSHA256");
  32                         hmac.init(secret);
  33                         cloud=new CloudComm(baseurl, encryptCipher, decryptCipher, hmac);
  34                 } catch (Exception e) {
  35                         throw new Error("Failed To Initialize Ciphers");
  36                 }
  37         }
  38
  39         private SecretKeySpec getKey(String password) {
  40                 try {
  41                         PBEKeySpec keyspec = new PBEKeySpec(password.toCharArray());
  42                         SecretKey key = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA256").generateSecret(keyspec);
  43                         SecretKeySpec secret = new SecretKeySpec(key.getEncoded(), "AES");
  44                         return secret;
  45                 } catch (Exception e) {
  46                         throw new Error("Failed generating key.");
  47                 }
  48         }
  49
  50         public void update() {
  51                 Slot[] newslots=cloud.getSlots(sequencenumber);
  52                 validateandupdate(newslots);
  53         }
  54
  55         void validateandupdate(Slot[] newslots) {
  56                 //The cloud communication layer has checked slot HMACs already
  57                 //before decoding
  58                 if (newslots.length==0)
  59                         return;
  60
  61                 long firstseqnum=newslots[0].getSequenceNumber();
  62                 if (firstseqnum < sequencenumber)
  63                         throw new Error("Server Error: Sent older slots!");
  64
  65                 SlotIndexer indexer = new SlotIndexer(newslots, buffer);
  66                 checkHMACChain(indexer, newslots);
  67                 for(Slot slot: newslots) {
  68                         processSlot(indexer, slot);
  69                 }
  70
  71         }
  72
  73         void processEntry(KeyValue entry, SlotIndexer indexer, Slot slot) {
  74
  75         }
  76
  77         void processEntry(LastMessage entry, SlotIndexer indexer, Slot slot) {
  78
  79         }
  80
  81         void processEntry(RejectedMessage entry, SlotIndexer indexer, Slot slot) {
  82
  83         }
  84
  85         void processEntry(TableStatus entry, SlotIndexer indexer, Slot slot) {
  86
  87         }
  88
  89         void processSlot(SlotIndexer indexer, Slot slot) {
  90                 for(Entry entry : slot.getEntries()) {
  91                         switch(entry.getType()) {
  92                         case Entry.TypeKeyValue:
  93                                 processEntry((KeyValue)entry, indexer, slot);
  94                                 break;
  95                         case Entry.TypeLastMessage:
  96                                 processEntry((LastMessage)entry, indexer, slot);
  97                                 break;
  98                         case Entry.TypeRejectedMessage:
  99                                 processEntry((RejectedMessage)entry, indexer, slot);
 100                                 break;
 101                         case Entry.TypeTableStatus:
 102                                 processEntry((TableStatus)entry, indexer, slot);
 103                                 break;
 104                         default:
 105                                 throw new Error("Unrecognized type: "+entry.getType());
 106                         }
 107                 }
 108         }
 109
 110         void checkHMACChain(SlotIndexer indexer, Slot[] newslots) {
 111                 for(int i=0; i < newslots.length; i++) {
 112                         Slot currslot=newslots[i];
 113                         Slot prevslot=indexer.getSlot(currslot.getSequenceNumber()-1);
 114                         if (prevslot != null &&
 115                                         !Arrays.equals(prevslot.getHMAC(), currslot.getPrevHMAC()))
 116                                 throw new Error("Server Error: Invalid HMAC Chain");
 117                 }
 118         }
 119 }