Text Secure is a great app for securing your messages from unauthorized access. The default SMS app of the phone will be replaced by this app after installation. A password can be set for Text Secure. Text Secure works best when both the sender and the receiver have Text Secure on their phones. If the receiver does not have Text Secure installed then also there is some level of security as all the sent and received messages of your phone will be encrypted by Text Secure.
This is an iPhone app and is similar to Text Secure in working. But it has additional features as well. Besides allowing the sender and receiver to have an encrypted text conversation it also allows the sender to delete full conversation both from the sender and receiver end. One glitch here is that this app requires a paid subscription to Silent Circle services.
This app allows you to make encrypted calls over the internet. You can initiate an encrypted call to a person who has RedPhone installed on his/her device. To call others who do not have RedPhone installed on their phone you’ll have to make a regular call. You can also use your data connection to make calls through RedPhone. This app is available on the Play Store.
PidGin can be used to encrypt your Google talk or Yahoo Messenger chats. All you need to do after installing this app is go to Tools -> Plugins -> and enable off the record messaging. Configure your plugin to generate a private encryption key. Now when you’ll chat with someone through PidGin and if the person you are chatting with also have off the record option enabled, you can initiate a private chat by clicking on the ‘Not private’ button and select Start Private Conversation from the drop down menu.