diff --git a/Graphics/twitter_header.png b/Graphics/twitter_header.png
new file mode 100644
index 000000000..498a3c093
Binary files /dev/null and b/Graphics/twitter_header.png differ
diff --git a/OpenKeychain/src/main/res/raw/help_about.md b/OpenKeychain/src/main/res/raw/help_about.md
index 45d326daa..c5e8ebccf 100644
--- a/OpenKeychain/src/main/res/raw/help_about.md
+++ b/OpenKeychain/src/main/res/raw/help_about.md
@@ -1,8 +1,8 @@
 [//]: # (NOTE: Please put every sentence in its own line, Transifex puts every line in its own translation field!)
 
-[http://www.openkeychain.org](http://www.openkeychain.org)
+[https://www.openkeychain.org](https://www.openkeychain.org)
 
-[OpenKeychain](http://www.openkeychain.org) is an OpenPGP implementation for Android.
+[OpenKeychain](https://www.openkeychain.org) is an OpenPGP implementation for Android.
 
 License: GPLv3+
 
@@ -61,11 +61,11 @@ License: GPLv3+
   * [Markdown4J](https://github.com/jdcasey/markdown4j) (Apache License v2)
   * [MaterialDrawer](https://github.com/mikepenz/MaterialDrawer) (Apache License v2)
   * [MiniDNS](https://github.com/rtreffer/minidns) (Apache License v2)
-  * [OkHttp](http://square.github.io/okhttp/) (Apache License v2)
+  * [OkHttp](https://square.github.io/okhttp/) (Apache License v2)
   * [PagerSlidingTabStrip](https://github.com/jpardogo/PagerSlidingTabStrip) (Material Design) (Apache License v2)
   * [SafeSlinger Exchange library](https://github.com/SafeSlingerProject/exchange-android) (MIT License)
   * [Snackbar](https://github.com/nispok/snackbar) (MIT License)
-  * [SpongyCastle](http://rtyley.github.com/spongycastle/) (MIT X11 License)
+  * [SpongyCastle](https://rtyley.github.io/spongycastle/) (MIT X11 License)
   * [StickyListHeaders](https://github.com/emilsjolander/StickyListHeaders) (Apache License v2)
   * [TokenAutoComplete](https://github.com/splitwise/TokenAutoComplete) (Apache License v2)
   * [ZXing](https://github.com/zxing/zxing) (Apache License v2)
diff --git a/README.md b/README.md
index e06366571..3144b4b77 100644
--- a/README.md
+++ b/README.md
@@ -1,7 +1,7 @@
 # OpenKeychain (for Android)
 
 OpenKeychain is an OpenPGP implementation for Android.  
-For a more detailed description and installation instructions go to http://www.openkeychain.org .
+For a more detailed description and installation instructions go to https://www.openkeychain.org .
 
 ### Branches
 * The development of OpenKeychain happens in the "master" branch.