Java tutorial
/* * Copyright 2012 The Stanford MobiSocial Laboratory * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package mobisocial.musubi.nearby; import gnu.trove.list.array.TByteArrayList; import java.io.BufferedReader; import java.io.InputStream; import java.io.InputStreamReader; import java.nio.ByteBuffer; import java.security.MessageDigest; import java.security.NoSuchAlgorithmException; import java.security.SecureRandom; import java.security.spec.AlgorithmParameterSpec; import java.util.Date; import java.util.List; import javax.crypto.Cipher; import javax.crypto.spec.IvParameterSpec; import javax.crypto.spec.SecretKeySpec; import mobisocial.crypto.IBHashedIdentity.Authority; import mobisocial.musubi.App; import mobisocial.musubi.model.MFeed; import mobisocial.musubi.model.MIdentity; import mobisocial.musubi.model.helpers.FeedManager; import mobisocial.musubi.model.helpers.IdentitiesManager; import mobisocial.musubi.nearby.location.GridHandler; import mobisocial.musubi.ui.MusubiBaseActivity; import mobisocial.musubi.ui.util.UiUtil; import mobisocial.musubi.util.MyLocation; import mobisocial.musubi.util.Util; import org.apache.http.HttpResponse; import org.apache.http.client.methods.HttpPost; import org.apache.http.entity.StringEntity; import org.apache.http.impl.client.DefaultHttpClient; import org.json.JSONArray; import org.json.JSONObject; import android.content.Context; import android.database.sqlite.SQLiteOpenHelper; import android.location.Location; import android.net.Uri; import android.os.AsyncTask; import android.util.Base64; import android.util.Log; import android.widget.Toast; /** * Shares a feed encrypted using the GPS server. */ public class GpsBroadcastTask extends AsyncTask<Void, Void, Void> { private final boolean DBG = MusubiBaseActivity.DBG; public static final String TAG = "GpsBroadcastTask"; private final Context mContext; private final String mmPassword; private final MyLocation mmMyLocation; private boolean mmLocationScanComplete = false; private Location mmLocation = null; private MFeed mFeed = null; private boolean mSucceeded = false; public GpsBroadcastTask(Context context, MFeed feed, String password) { mmPassword = password; mmMyLocation = new MyLocation(); mContext = context; mFeed = feed; } @Override protected void onPreExecute() { mmMyLocation.getLocation(mContext, mmLocationResult); } @Override protected Void doInBackground(Void... params) { if (DBG) Log.d(TAG, "Uploading group for nearby gps..."); while (!mmLocationScanComplete) { synchronized (mmLocationResult) { if (!mmLocationScanComplete) { try { if (DBG) Log.d(TAG, "Waiting for location results..."); mmLocationResult.wait(); } catch (InterruptedException e) { } } } } if (DBG) Log.d(TAG, "Got location " + mmLocation); if (isCancelled()) { return null; } try { SQLiteOpenHelper db = App.getDatabaseSource(mContext); FeedManager fm = new FeedManager(db); IdentitiesManager im = new IdentitiesManager(db); String group_name = UiUtil.getFeedNameFromMembersList(fm, mFeed); byte[] group_capability = mFeed.capability_; List<MIdentity> owned = im.getOwnedIdentities(); MIdentity sharer = null; for (MIdentity i : owned) { if (i.type_ != Authority.Local) { sharer = i; break; } } String sharer_name = UiUtil.safeNameForIdentity(sharer); byte[] sharer_hash = sharer.principalHash_; byte[] thumbnail = fm.getFeedThumbnailForId(mFeed.id_); if (thumbnail == null) thumbnail = im.getMusubiThumbnail(sharer) != null ? sharer.musubiThumbnail_ : im.getThumbnail(sharer); int member_count = fm.getFeedMemberCount(mFeed.id_); JSONObject group = new JSONObject(); group.put("group_name", group_name); group.put("group_capability", Base64.encodeToString(group_capability, Base64.DEFAULT)); group.put("sharer_name", sharer_name); group.put("sharer_type", sharer.type_.ordinal()); group.put("sharer_hash", Base64.encodeToString(sharer_hash, Base64.DEFAULT)); if (thumbnail != null) group.put("thumbnail", Base64.encodeToString(thumbnail, Base64.DEFAULT)); group.put("member_count", member_count); byte[] key = Util.sha256(("happysalt621" + mmPassword).getBytes()); byte[] data = group.toString().getBytes(); byte[] iv = new byte[16]; new SecureRandom().nextBytes(iv); byte[] partial_enc_data; Cipher cipher; AlgorithmParameterSpec iv_spec; SecretKeySpec sks; try { cipher = Cipher.getInstance("AES/CBC/PKCS7Padding"); } catch (Exception e) { throw new RuntimeException("AES not supported on this platform", e); } try { iv_spec = new IvParameterSpec(iv); sks = new SecretKeySpec(key, "AES"); cipher.init(Cipher.ENCRYPT_MODE, sks, iv_spec); } catch (Exception e) { throw new RuntimeException("bad iv or key", e); } try { partial_enc_data = cipher.doFinal(data); } catch (Exception e) { throw new RuntimeException("body encryption failed", e); } TByteArrayList bal = new TByteArrayList(iv.length + partial_enc_data.length); bal.add(iv); bal.add(partial_enc_data); byte[] enc_data = bal.toArray(); if (DBG) Log.d(TAG, "Posting to gps server..."); Uri uri = Uri.parse("http://bumblebee.musubi.us:6253/nearbyapi/0/sharegroup"); StringBuffer sb = new StringBuffer(); DefaultHttpClient client = new DefaultHttpClient(); HttpPost httpPost = new HttpPost(uri.toString()); httpPost.addHeader("Content-Type", "application/json"); JSONArray buckets = new JSONArray(); JSONObject descriptor = new JSONObject(); double lat = mmLocation.getLatitude(); double lng = mmLocation.getLongitude(); long[] coords = GridHandler.getGridCoords(lat, lng, 5280 / 2); for (long c : coords) { MessageDigest md; try { byte[] obfuscate = ("sadsalt193s" + mmPassword).getBytes(); md = MessageDigest.getInstance("SHA-256"); ByteBuffer b = ByteBuffer.allocate(8 + obfuscate.length); b.putLong(c); b.put(obfuscate); String secret_bucket = Base64.encodeToString(md.digest(b.array()), Base64.DEFAULT); buckets.put(buckets.length(), secret_bucket); } catch (NoSuchAlgorithmException e) { throw new RuntimeException("your platform does not support sha256", e); } } descriptor.put("buckets", buckets); descriptor.put("data", Base64.encodeToString(enc_data, Base64.DEFAULT)); descriptor.put("expiration", new Date().getTime() + 1000 * 60 * 60); httpPost.setEntity(new StringEntity(descriptor.toString())); try { HttpResponse execute = client.execute(httpPost); InputStream content = execute.getEntity().getContent(); BufferedReader buffer = new BufferedReader(new InputStreamReader(content)); String s = ""; while ((s = buffer.readLine()) != null) { if (isCancelled()) { return null; } sb.append(s); } if (sb.toString().equals("ok")) mSucceeded = true; else { System.err.println(sb); } } catch (Exception e) { e.printStackTrace(); } //TODO: report failures etc } catch (Exception e) { Log.e(TAG, "Failed to broadcast group", e); } return null; } @Override protected void onPostExecute(Void result) { Toast.makeText(mContext, mSucceeded ? "Shared group nearby" : "Error sharing group", Toast.LENGTH_LONG) .show(); } private final MyLocation.LocationResult mmLocationResult = new MyLocation.LocationResult() { @Override public void gotLocation(final Location location) { if (DBG) Log.d(TAG, "got location"); mmLocation = location; mmLocationScanComplete = true; synchronized (mmLocationResult) { mmLocationResult.notify(); } } }; }