diff --git a/.gitmodules b/.gitmodules
index f8db64f0a..8238c3f80 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,12 +1,6 @@
 [submodule "extern/StickyListHeaders"]
 	path = extern/StickyListHeaders
 	url = https://github.com/open-keychain/StickyListHeaders.git
-[submodule "extern/zxing-android-integration"]
-	path = extern/zxing-android-integration
-	url = https://github.com/open-keychain/zxing-android-integration.git
-[submodule "extern/zxing-qr-code"]
-	path = extern/zxing-qr-code
-	url = https://github.com/open-keychain/zxing-qr-code.git
 [submodule "extern/spongycastle"]
 	path = extern/spongycastle
 	url = https://github.com/open-keychain/spongycastle.git
@@ -19,9 +13,6 @@
 [submodule "extern/openkeychain-api-lib"]
 	path = extern/openkeychain-api-lib
 	url = https://github.com/open-keychain/openkeychain-api-lib.git
-[submodule "extern/SuperToasts"]
-	path = extern/SuperToasts
-	url = https://github.com/open-keychain/SuperToasts.git
 [submodule "extern/KeybaseLib"]
 	path = extern/KeybaseLib
 	url = https://github.com/open-keychain/KeybaseLib.git
diff --git a/OpenKeychain/build.gradle b/OpenKeychain/build.gradle
index 7fa139c06..4567f54dc 100644
--- a/OpenKeychain/build.gradle
+++ b/OpenKeychain/build.gradle
@@ -1,4 +1,5 @@
 apply plugin: 'com.android.application'
+apply plugin: 'witness'
 
 dependencies {
     // NOTE: Always use fixed version codes not dynamic ones, e.g. 0.7.3 instead of 0.7.+, see README for more information
@@ -15,13 +16,12 @@ dependencies {
     compile project(':extern:spongycastle:pg')
     compile project(':extern:spongycastle:pkix')
     compile project(':extern:spongycastle:prov')
-    compile project(':extern:SuperToasts:supertoasts')
     compile project(':extern:minidns')
     compile project(':extern:KeybaseLib:Lib')
     compile project(':extern:TokenAutoComplete:library')
     compile project(':extern:safeslinger-exchange')
 
-    // TODO: Pin!
+    // NOTE: libraries are pinned to a specific build, see below
     compile 'com.eftimoff:android-patternview:1.0.0@aar'
     compile 'com.journeyapps:zxing-android-embedded:2.0.1@aar'
     compile 'com.journeyapps:zxing-android-integration:2.0.1@aar'
@@ -32,9 +32,42 @@ dependencies {
     compile 'com.getbase:floatingactionbutton:1.8.0'
 }
 
+// Output of ./gradlew -q calculateChecksums
+// Comment out the libs referenced as git submodules!
+dependencyVerification {
+    verify = [
+        'com.android.support:support-v4:703572d3015a088cc5604b7e38885af3d307c829d0c5ceaf8654ff41c71cd160',
+        'com.android.support:appcompat-v7:5dbeb5316d0a6027d646ae552804c3baa5e3bd53f7f33db50904d51505c8a0e5',
+        'com.android.support:recyclerview-v7:e525ad3f33c84bb12b73d2dc975b55364a53f0f2d0697e043efba59ba73e22d2',
+        'com.android.support:cardview-v7:45c48c2ab056bc7a8573970b10f8902742c5d443f180dae43c56557397ac39af',
+        //'OpenKeychain.extern:openpgp-api-lib:b17bb282321351e4b00b4cd6422a57aadc13decae264019a88707bcb556439ea',
+        //'OpenKeychain.extern:openkeychain-api-lib:5f95f01c066069d4bde68992fd8da5faac21510d009b1fdae7a2e28e43e82cf4',
+        //'OpenKeychain.extern:html-textview:b58e343cf4c145e91f888806d06a2a7770a9e9331a72f08cfcf1128db30dcff3',
+        //'OpenKeychain.extern.StickyListHeaders:library:24e25da422efc08e4e7a06efbe927fdf17f7a9aa722db2b983385e2bf0004da5',
+        //'com.madgag.spongycastle:core:a9e4f60afe6b2661e0713190ade92c099b3f74ebbc67c1bc3e3fced0144307f4',
+        //'com.madgag.spongycastle:pg:29d544ff289fcaafcf6c3904185f5a6fbdb623cf1a1e377fcb239edc31ee9c17',
+        //'com.madgag.spongycastle:pkix:950d6eac8205c6a24aa87066fbf9cd0af50b95858b8d2b18d53e2fada2dbb2e3',
+        //'com.madgag.spongycastle:prov:0b78ffd7a59b1b690a05ebe9bb31d43405046a44a18e0529d7c826acb56350b7',
+        //'OpenKeychain.extern:minidns:cf332e993d7fcdc0a3821f5b997944df40582dc6c9f0ea36b5e20c1e289cb19f',
+        //'OpenKeychain.extern.KeybaseLib:Lib:af9bff087148e0859430d0b99ece096c41b315c5dc1ed500a68580b9b0e5ab11',
+        //'OpenKeychain.extern.TokenAutoComplete:library:40d4212a95e947efdb02f2ca66c95a27d49fba848471a6317eca2b9cc18e8780',
+        //'OpenKeychain.extern:safeslinger-exchange:94a1ce68217af7499579a042758283b1530912c53241bdfa06d1a079a5ae3faf',
+        'com.eftimoff:android-patternview:a031eaed3b5cef8ea06c2d4a6e27693937f89ae483598d61b7027eeee0bed408',
+        'com.journeyapps:zxing-android-embedded:5d6ba3931bd0b999695e363b571e95bd6bc9956340c1e6ce740cd0bff3d89a50',
+        'com.journeyapps:zxing-android-integration:6f50bb07c057ac94319777ddfbb66f5d4f6190393418b2fc861e0e60d06f3c0d',
+        'com.google.zxing:core:38c49045765281e4c170062fa3f48e4e988629bf985cab850c7497be5eaa72a1',
+        'com.jpardogo.materialtabstrip:library:c6ef812fba4f74be7dc4a905faa4c2908cba261a94c13d4f96d5e67e4aad4aaa',
+        'it.neokree:MaterialNavigationDrawer:1174d751a54689fccf53c1fbcdf439745926ae19024f4f1017afb6b29643c57d',
+        'com.nispok:snackbar:59dc092a44c877e9ce5f9040c632d99e62d8932b0a4d67ba0ec9e35467d9047c',
+        'com.getbase:floatingactionbutton:e63966148212e9685afad2370780ea239b6dbd2a06f6a3f919b98882318e6a32',
+        'com.android.support:support-annotations:fdee2354787ef66b268e75958de3f7f6c4f8f325510a6dac9f49c929f83a63de',
+        'com.balysv:material-ripple:587f19c1e27f16c7dc67ff9ac73838aa1451086ef05a15cee38bee3e4e1454ae',
+    ]
+}
+
 android {
-    compileSdkVersion 21
-    buildToolsVersion '21.1.2'
+    compileSdkVersion rootProject.ext.compileSdkVersion
+    buildToolsVersion rootProject.ext.buildToolsVersion
 
     defaultConfig {
         minSdkVersion 15
diff --git a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/util/ContactHelper.java b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/util/ContactHelper.java
index 60bc846b2..3cf201ed7 100644
--- a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/util/ContactHelper.java
+++ b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/util/ContactHelper.java
@@ -57,10 +57,20 @@ public class ContactHelper {
             KeychainContract.KeyRings.MASTER_KEY_ID,
             KeychainContract.KeyRings.EXPIRY,
             KeychainContract.KeyRings.IS_REVOKED};
+
+    public static final int INDEX_USER_ID = 0;
+    public static final int INDEX_FINGERPRINT = 1;
+    public static final int INDEX_KEY_ID = 2;
+    public static final int INDEX_MASTER_KEY_ID = 3;
+    public static final int INDEX_EXPIRY = 4;
+    public static final int INDEX_IS_REVOKED = 5;
+
     public static final String[] USER_IDS_PROJECTION = new String[]{
             UserPackets.USER_ID
     };
 
+    public static final int INDEX_USER_IDS_USER_ID = 0;
+
     public static final String NON_REVOKED_SELECTION = UserPackets.IS_REVOKED + "=0";
 
     public static final String[] ID_PROJECTION = new String[]{ContactsContract.RawContacts._ID};
@@ -301,23 +311,26 @@ public class ContactHelper {
                 null, null, null);
         if (cursor != null) {
             while (cursor.moveToNext()) {
-                String[] primaryUserId = KeyRing.splitUserId(cursor.getString(0));
-                String fingerprint = KeyFormattingUtils.convertFingerprintToHex(cursor.getBlob(1));
+                String[] primaryUserId = KeyRing.splitUserId(cursor.getString(INDEX_USER_ID));
+                String fingerprint = KeyFormattingUtils.convertFingerprintToHex(cursor.getBlob(INDEX_FINGERPRINT));
                 contactFingerprints.remove(fingerprint);
-                String keyIdShort = KeyFormattingUtils.convertKeyIdToHexShort(cursor.getLong(2));
-                long masterKeyId = cursor.getLong(3);
-                boolean isExpired = !cursor.isNull(4) && new Date(cursor.getLong(4) * 1000).before(new Date());
-                boolean isRevoked = cursor.getInt(5) > 0;
+                String keyIdShort = KeyFormattingUtils.convertKeyIdToHexShort(cursor.getLong(INDEX_KEY_ID));
+                long masterKeyId = cursor.getLong(INDEX_MASTER_KEY_ID);
+                boolean isExpired = !cursor.isNull(INDEX_EXPIRY)
+                        && new Date(cursor.getLong(INDEX_EXPIRY) * 1000).before(new Date());
+                boolean isRevoked = cursor.getInt(INDEX_IS_REVOKED) > 0;
                 int rawContactId = findRawContactId(resolver, fingerprint);
                 ArrayList<ContentProviderOperation> ops = new ArrayList<>();
 
+                Log.d(Constants.TAG, "raw contact id: "+rawContactId);
+
                 // Do not store expired or revoked keys in contact db - and remove them if they already exist
                 if (isExpired || isRevoked) {
                     if (rawContactId != -1) {
                         resolver.delete(ContactsContract.RawContacts.CONTENT_URI, ID_SELECTION,
                                 new String[]{Integer.toString(rawContactId)});
                     }
-                } else {
+                } else if (primaryUserId[0] != null) {
 
                     // Create a new rawcontact with corresponding key if it does not exist yet
                     if (rawContactId == -1) {
diff --git a/OpenKeychain/src/main/res/values/colors.xml b/OpenKeychain/src/main/res/values/colors.xml
index c49e06b4b..8c5358fd0 100644
--- a/OpenKeychain/src/main/res/values/colors.xml
+++ b/OpenKeychain/src/main/res/values/colors.xml
@@ -13,6 +13,8 @@
 
     <!-- Other colors -->
 
+    <color name="black">#000000</color>
+
     <color name="primary_light">#C8E6C9</color>
     <color name="fab">@color/accent</color>
     <color name="fab_pressed">#1976D2</color>
diff --git a/OpenKeychain/src/main/res/values/strings.xml b/OpenKeychain/src/main/res/values/strings.xml
index 2d599e984..ca6ce1f7d 100644
--- a/OpenKeychain/src/main/res/values/strings.xml
+++ b/OpenKeychain/src/main/res/values/strings.xml
@@ -359,8 +359,7 @@
     <string name="progress_con_reimport">"consolidate: reimporting…"</string>
 
     <!-- action strings -->
-    <string name="hint_keyserver_search_hint">"Name/Email/Key ID…"</string>
-    <string name="hint_cloud_search_hint">"Name/Email/Proof/Key…"</string>
+    <string name="hint_cloud_search_hint">"Search via Name, Email…"</string>
 
     <!-- key bit length selections -->
     <string name="key_size_512">"512"</string>
diff --git a/README.md b/README.md
index 991757169..83655ce01 100644
--- a/README.md
+++ b/README.md
@@ -106,37 +106,50 @@ see
 * Mailinglist Archive at http://bouncy-castle.1462172.n4.nabble.com/Bouncy-Castle-Dev-f1462173.html
 * Commit changelog of pg subpackage: https://github.com/bcgit/bc-java/commits/master/pg
 
-
-## Notes
-
-### Gradle Build System
+## Build System
 
 We try to make our builds as [reproducible/deterministic](https://blog.torproject.org/blog/deterministic-builds-part-one-cyberwar-and-global-compromise) as possible.  
-When changing build files or dependencies, respect the following requirements:
-* No precompiled libraries (you never know what pre-compiled jar files really contain!). All libraries should be forked into the open-keychain Github project and then provided as git submodules in the "extern" folder.
-* No dependencies from Maven (also a soft requirement for inclusion in [F-Droid](https://f-droid.org))
+
+#### Update Gradle version
 * Always use a fixed Android Gradle plugin version not a dynamic one, e.g. ``0.7.3`` instead of ``0.7.+`` (allows offline builds without lookups for new versions, also some minor Android plugin versions had serious issues, i.e. [0.7.2 and 0.8.1](http://tools.android.com/tech-docs/new-build-system))
-* Commit the corresponding [Gradle wrapper](http://www.gradle.org/docs/current/userguide/gradle_wrapper.html) to the repository (allows easy building for new contributors without the need to install the required Gradle version using a package manager)
-* In order to update the build system to a newer gradle version you need to:
-  * Update every build.gradle file with the new gradle version and/or gradle plugin version
+* Update every build.gradle file with the new gradle version and/or gradle plugin version
     * build.gradle
     * OpenKeychain/build.gradle
-    * OpenKeychain-API/build.gradle
-    * OpenKeychain-API/example-app/build.gradle
-    * OpenKeychain-API/libraries/keychain-api-library/build.gradle
-  * run ./gradlew wrapper twice to update gradle and download the new gradle jar file
-  * commit the new gradle jar and property files
+* run ./gradlew wrapper twice to update gradle and download the new gradle jar file
+* commit the corresponding [Gradle wrapper](http://www.gradle.org/docs/current/userguide/gradle_wrapper.html) to the repository (allows easy building for new contributors without the need to install the required Gradle version using a package manager)
+  
+#### Update SDK and Build Tools
+* Open build.gradle and change:
+```
+ext {
+    compileSdkVersion = 21
+    buildToolsVersion = '21.1.2'
+}
+```
+* Change SDK and Build Tools in git submodules "openkeychain-api-lib" and "openpgp-api-lib" manually. They should also build on their own without the ext variables.
 
-### Slow Gradle?
+#### Add new library
+* You can add the library as a Maven dependency or as a git submodule (if patches are required) in the "extern" folder.
+* If added as a Maven dependency, pin the library using [Gradle Witness](https://github.com/WhisperSystems/gradle-witness) (Do ``./gradlew -q calculateChecksums`` for Trust on First Use)
+* If added as a git submodule, change the ``compileSdkVersion`` and ``buildToolsVersion`` in build.gradle to use the variables from the root project:
+```
+android {
+    compileSdkVersion rootProject.ext.compileSdkVersion
+    buildToolsVersion rootProject.ext.buildToolsVersion
+}
+```
+* You can check for wrong ``compileSdkVersion`` by ``find -name build.gradle | xargs grep compileSdkVersion``
+
+#### Slow Gradle?
 
 * https://www.timroes.de/2013/09/12/speed-up-gradle/
 * Disable Lint checking if it is enabled in build.gradle
 
-### Error:Configuration with name 'default' not found.
+#### Error:Configuration with name 'default' not found.
 
 Gradle project dependencies are missing. Do a ``git submodule init && git submodule update``
 
-### Translations
+## Translations
 
 Translations are hosted on Transifex, which is configured by ".tx/config".
 
diff --git a/build.gradle b/build.gradle
index f8e6afc27..6b3eb2c3d 100644
--- a/build.gradle
+++ b/build.gradle
@@ -6,6 +6,7 @@ buildscript {
     dependencies {
         // NOTE: Always use fixed version codes not dynamic ones, e.g. 0.7.3 instead of 0.7.+, see README for more information
         classpath 'com.android.tools.build:gradle:1.0.0'
+        classpath files('gradle-witness.jar')
     }
 }
 
@@ -38,3 +39,10 @@ project(':extern:spongycastle') {
         test.enabled = false
     }
 }
+
+// SDK Version and Build Tools used by all subprojects
+// See http://tools.android.com/tech-docs/new-build-system/tips#TOC-Controlling-Android-properties-of-all-your-modules-from-the-main-project.
+ext {
+    compileSdkVersion = 21
+    buildToolsVersion = '21.1.2'
+}
\ No newline at end of file
diff --git a/extern/KeybaseLib b/extern/KeybaseLib
index 2b26d163d..9615d90b1 160000
--- a/extern/KeybaseLib
+++ b/extern/KeybaseLib
@@ -1 +1 @@
-Subproject commit 2b26d163df84a3d26c1c8da088ed3811b5ca6ec7
+Subproject commit 9615d90b18d1aee4dad994aa45875adfdcfb3c34
diff --git a/extern/StickyListHeaders b/extern/StickyListHeaders
index 62cc58c12..70a2ed806 160000
--- a/extern/StickyListHeaders
+++ b/extern/StickyListHeaders
@@ -1 +1 @@
-Subproject commit 62cc58c12d0c09b50984caf26e5afceda8873784
+Subproject commit 70a2ed80632938540bf07b81270384f4e5a96f9e
diff --git a/extern/SuperToasts b/extern/SuperToasts
deleted file mode 160000
index 77042d633..000000000
--- a/extern/SuperToasts
+++ /dev/null
@@ -1 +0,0 @@
-Subproject commit 77042d633f4dd430bcc86101e31dda52433db9c1
diff --git a/extern/TokenAutoComplete b/extern/TokenAutoComplete
index ca46b4261..1d6d3882e 160000
--- a/extern/TokenAutoComplete
+++ b/extern/TokenAutoComplete
@@ -1 +1 @@
-Subproject commit ca46b4261c97221ddd4db135e7838d6fa145adf4
+Subproject commit 1d6d3882e711c14c93abf73cbcbd28b9e0e2b498
diff --git a/extern/html-textview b/extern/html-textview
index eedaa334e..9872a7315 160000
--- a/extern/html-textview
+++ b/extern/html-textview
@@ -1 +1 @@
-Subproject commit eedaa334e761273efbfc49ded2124df58c8a4d88
+Subproject commit 9872a73156518fd8df79dd2cd4d24750574b9ac7
diff --git a/extern/openkeychain-api-lib b/extern/openkeychain-api-lib
index 88c004793..925907502 160000
--- a/extern/openkeychain-api-lib
+++ b/extern/openkeychain-api-lib
@@ -1 +1 @@
-Subproject commit 88c00479329c1aa892bef052f3f8830067c386d8
+Subproject commit 9259075028e0906d0cb085e0c4578e23829dc3c0
diff --git a/extern/safeslinger-exchange b/extern/safeslinger-exchange
index 96f7c8935..7c84cb54d 160000
--- a/extern/safeslinger-exchange
+++ b/extern/safeslinger-exchange
@@ -1 +1 @@
-Subproject commit 96f7c893565e3a8badd740b2035beea87d8bffb3
+Subproject commit 7c84cb54df5b3d5c6780984e48f3e9e4cbc5128e
diff --git a/extern/zxing-android-integration b/extern/zxing-android-integration
deleted file mode 160000
index e2d0064bd..000000000
--- a/extern/zxing-android-integration
+++ /dev/null
@@ -1 +0,0 @@
-Subproject commit e2d0064bd3171b7333af044bb30c25c85ee993dd
diff --git a/extern/zxing-qr-code b/extern/zxing-qr-code
deleted file mode 160000
index 8fd0657d3..000000000
--- a/extern/zxing-qr-code
+++ /dev/null
@@ -1 +0,0 @@
-Subproject commit 8fd0657d33d8277aadbdc1604fd3aaa2e8d4b487
diff --git a/gradle-witness.jar b/gradle-witness.jar
new file mode 100644
index 000000000..90d2a364c
Binary files /dev/null and b/gradle-witness.jar differ