honour the pass phrase cache TTL by running a timer and removing expired cached pass phrases

4 files changed, 55 insertions, 9 deletions

diff --git a/src/org/thialfihar/android/apg/Apg.java b/src/org/thialfihar/android/apg/Apg.java
index a453cdf4a..5071e3d01 100644
--- a/src/org/thialfihar/android/apg/Apg.java
+++ b/src/org/thialfihar/android/apg/Apg.java
@@ -41,6 +41,7 @@ import java.util.Date;
 import java.util.GregorianCalendar;

 import java.util.HashMap;

 import java.util.Iterator;

+import java.util.Map;

 import java.util.Vector;

 import java.util.regex.Pattern;

 

@@ -293,9 +294,26 @@ public class Apg {
         if (cpp == null) {

             return null;

         }

+        // set it again to reset the cache life cycle

+        setCachedPassPhrase(realId, cpp.passPhrase);

         return cpp.passPhrase;

     }

 

+    public static void cleanUpCache(int ttl) {

+        long now = new Date().getTime();

+

+        Vector<Long> oldKeys = new Vector<Long>();

+        for (Map.Entry<Long, CachedPassPhrase> pair : mPassPhraseCache.entrySet()) {

+            if ((now - pair.getValue().timestamp) >= 1000 * ttl) {

+                oldKeys.add(pair.getKey());

+            }

+        }

+

+        for (long keyId : oldKeys) {

+            mPassPhraseCache.remove(keyId);

+        }

+    }

+

     public static PGPSecretKey createKey(Context context,

                                          int algorithmChoice, int keySize, String passPhrase,

                                          PGPSecretKey masterKey)

@@ -1266,7 +1284,7 @@ public class Apg {
 

         PGPSignatureGenerator signatureGenerator = null;

         progress.setProgress(R.string.progress_preparingStreams, 5, 100);

-        // encryptFile and compress input file content

+        // encrypt and compress input file content

         PGPEncryptedDataGenerator cPk =

                 new PGPEncryptedDataGenerator(symmetricAlgorithm, true, new SecureRandom(),

                                               new BouncyCastleProvider());

diff --git a/src/org/thialfihar/android/apg/BaseActivity.java b/src/org/thialfihar/android/apg/BaseActivity.java
index 70ddb7402..244c4aee6 100644
--- a/src/org/thialfihar/android/apg/BaseActivity.java
+++ b/src/org/thialfihar/android/apg/BaseActivity.java
@@ -17,6 +17,8 @@
 package org.thialfihar.android.apg;

 

 import java.io.File;

+import java.util.Timer;

+import java.util.TimerTask;

 

 import org.bouncycastle2.bcpg.HashAlgorithmTags;

 import org.bouncycastle2.openpgp.PGPEncryptedData;

@@ -50,6 +52,8 @@ public class BaseActivity extends Activity
     private String mDeleteFile = null;

     protected static SharedPreferences mPreferences = null;

 

+    private static Timer mCacheTimer = new Timer();

+

     private Handler mHandler = new Handler() {

         @Override

         public void handleMessage(Message msg) {

@@ -65,6 +69,29 @@ public class BaseActivity extends Activity
             mPreferences = getPreferences(MODE_PRIVATE);

         }

         Apg.initialize(this);

+        if (mCacheTimer == null) {

+            setPassPhraseCacheTimer();

+        }

+    }

+

+    private void setPassPhraseCacheTimer() {

+        if (mCacheTimer != null) {

+            mCacheTimer.cancel();

+            mCacheTimer = null;

+        }

+        int ttl = getPassPhraseCacheTtl();

+        if (ttl == 0) {

+            // no timer needed

+            return;

+        }

+        // check every ttl/2 seconds, which shouldn't be heavy on the device (even if ttl = 15),

+        // and makes sure the longest a pass phrase survives int the cache is 1.5 * ttl

+        mCacheTimer = new Timer();

+        mCacheTimer.scheduleAtFixedRate(new TimerTask() {

+            public void run() {

+                Apg.cleanUpCache(BaseActivity.this.getPassPhraseCacheTtl());

+            }

+        }, 0, ttl * 1000 / 2);

     }

 

     @Override

@@ -98,7 +125,6 @@ public class BaseActivity extends Activity
 

     @Override

     protected Dialog onCreateDialog(int id) {

-

         // in case it is a progress dialog

         mProgressDialog = new ProgressDialog(this);

         mProgressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);

@@ -354,14 +380,16 @@ public class BaseActivity extends Activity
         return mSecretKeyId;

     }

 

-    public int getPassPhraseCache() {

-        return mPreferences.getInt(Constants.pref.pass_phrase_cache_length, 300);

+    public int getPassPhraseCacheTtl() {

+        return mPreferences.getInt(Constants.pref.pass_phrase_cache_ttl, 300);

     }

 

-    public void setPassPhraseCache(int value) {

+    public void setPassPhraseCacheTtl(int value) {

         SharedPreferences.Editor editor = mPreferences.edit();

-        editor.putInt(Constants.pref.pass_phrase_cache_length, value);

+        editor.putInt(Constants.pref.pass_phrase_cache_ttl, value);

         editor.commit();

+

+        setPassPhraseCacheTimer();

     }

 

     public int getDefaultEncryptionAlgorithm() {

diff --git a/src/org/thialfihar/android/apg/Constants.java b/src/org/thialfihar/android/apg/Constants.java
index 40a77645d..a880d3328 100644
--- a/src/org/thialfihar/android/apg/Constants.java
+++ b/src/org/thialfihar/android/apg/Constants.java
@@ -28,6 +28,6 @@ public final class Constants {
         public static final String default_encryption_algorithm = "defaultEncryptionAlgorithm";

         public static final String default_hash_algorithm = "defaultHashAlgorithm";

         public static final String default_ascii_armour = "defaultAsciiArmour";

-        public static final String pass_phrase_cache_length = "passPhraseCacheLength";

+        public static final String pass_phrase_cache_ttl = "passPhraseCacheTtl";

     }

 }

diff --git a/src/org/thialfihar/android/apg/PreferencesActivity.java b/src/org/thialfihar/android/apg/PreferencesActivity.java
index 8a1c02475..f6bc4c8b4 100644
--- a/src/org/thialfihar/android/apg/PreferencesActivity.java
+++ b/src/org/thialfihar/android/apg/PreferencesActivity.java
@@ -55,7 +55,7 @@ public class PreferencesActivity extends BaseActivity {
         adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);

         mPassPhraseCache.setAdapter(adapter);

 

-        int passPhraseCache = getPassPhraseCache();

+        int passPhraseCache = getPassPhraseCacheTtl();

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

             if (choices[i].getId() == passPhraseCache) {

                 mPassPhraseCache.setSelection(i);

@@ -66,7 +66,7 @@ public class PreferencesActivity extends BaseActivity {
         mPassPhraseCache.setOnItemSelectedListener(new OnItemSelectedListener() {

             @Override

             public void onItemSelected(AdapterView<?> adapter, View view, int index, long id) {

-                setPassPhraseCache(((Choice) mPassPhraseCache.getSelectedItem()).getId());

+                setPassPhraseCacheTtl(((Choice) mPassPhraseCache.getSelectedItem()).getId());

             }

 

             @Override