Talk freely

It's hard to give a product as threema to write a review. The issue is politically charged and opinions differ widely. I will therefore as far as possible be limited to facts and as far as I present you with my opinion, then only as an inspiration for others and not as patronizing, it's just "my opinion". In the event that there are divergent opinions, I ask the reader to the fairness to used the comment function and not to evaluate single negative. Thank you!

So, now but to threema:
What's threema: A Messenger as Whatsapp, but with encryption. Who does not know even WhatsApp, perhaps knows ICQ or AIM, something like this for your mobile phone or tablet just to take SMS and MMS via the Internet data such as images, videos and chats to exchange for free either in direct exchange with a person or group chat.

Coding
"New" threema now is that it veschlüsselt all exchanged data before sending it to the mobile phone of the user and only the recipient can decrypt it. Threema themselves or third parties so they can not follow along. In the previous top dog Whatsapp (which was just bought for 18 billion of Facebook), this is not so, and one of the reasons for the high purchase price was probably mentioned that Facebook data at least internally can be used for profiling.

The threema program is closed source, ie, the program source code is not publicly available, ie it could theoretically give backdoors. This is perhaps one of the most important counter-arguments against threema. Ultimately, argued threema that they have to earn money to operate the server for Threma. Since they do not want to do with advertising and selling user data that they need to just ask for the money program. Explain now how the program works in detail, it will soon be free replicas and then no one will pay for threema. The argument makes sense to me.
In addition, the problem is greatly mitigated by a further aspect: threema used for Veschlüsselung an open source library called NaCl with its visible source. Even if the rest of threema closed source, so there are already analyzes the network that is actually used the NaCl library and well-implemented correctly. I add the links this in the comments.

The encryption uses asymmetric methods and means for secure key exchange. For the details I have analyzed phloem - around the frame not to blow here - refer to Google and Wikipedia. One can therefore comfortably leave to others their own key to come via the Internet, it is safe to state of the art. You can also transfer personal contact about the key via QR Code.

Installation and usage
The program works well: Installation is simple, crashes I have not experienced. The modules to take advantage of the camera (approximately also to other people's keys to encrypt and decrypt read as QR code) to be used and the microphone (to send some to voice messages) are spun off as an extra optional modules, so you can decide individually if you can do without this feature and then has to be no appropriate access rights to threema. These modules are never crashed on me.
The operation is similar to WhatsApp, one feels at home immediately. But there are more options, for example, you can decide whether other people can find a reference to the telephone number or not. I missed no function that I knew of Whatsapp.
I have a quad-core processor in the mobile phone and noticed by encrypting any delay.

Personal experiences:
Of course, currently much more people use Whatsapp as threema. In many cases threema can merely because one wants to get in touch with people who have WhatsApp ONLY, Whatsapp unreplaced.
I'm not a missionary who wants to change that. Nevertheless, I have decreed in my closest circle threema, or the belief spread that it is practical, easy abfotographieren also sensitive documents via cell phone and can send encrypted.
I assume that the encryption is secure. This must each decide for themselves. One assumes, however, it is really convenient to be able to also send secret data, without having to pass by mail or in person.

In addition, I still also used Whatsapp, also because of the established chat groups.

I hope this review and these experiences are helpful. In the event that dissenting opinions or comments made, I ask the reader to the fairness to used the comment function and not to evaluate single negative. Thank you!