I just read about tow new apps that run on Android to secure your cell phone communications. They are Red Phone and Text Secure. You will be able to view the source code for these apps. It is limited to the Android platform, and for calls in the USA only.
Red Phone is an end to end encryption solution for voice calls. It uses ZRTP encryption developed by the dude who brought you PKZIP. This is a VOIP implementation. So the calls do not use up your cell phone minutes. Instead you communicate over Wifi or 3G. It uses SMS to initiate the calls.
Text Secure uses the Off The Record protocol. All messages are stored in an encrypted database on your phone. Messages are compressed and sent via SMS. This technology is based on the NSA Suite B standard. That is the same one used for Top Secret government communications. So you know it is secure.
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