What’s special about Threema’s privacy protection?
Comprehensive privacy protection requires solid message encryption, but there is more to it.
Threema can be used without providing any personal information whatsoever; linking a phone number and/or email address to your Threema ID is optional.
Optional contact synchronization
Synchronizing your address book in order to retrieve your contacts’ Threema IDs (provided they have linked them, see above) is optional. If you don’t want to grant access to your address book, you can either scan your contacts’ Threema IDs or add them manually.
In case you enable contact synchronization or link your ID with a phone number or email address, you can rest assured that Threema uses this information only temporarily for the specified purpose. Personal information is always hashed, both in transit and on disk.
All data involved in communication other than the actual content is metadata. Serious privacy protection must include both protection of content and protection of metadata. The sole protection of content is insufficient because metadata allows to uniquely identify individuals, analyze their behavior, determine their circles of friends, detect their frequent locations, and monitor their communication behavior. Combined with data from other platforms, the picture that can be drawn of a person is much more detailed than one that could ever be drawn from message contents alone. It’s likely that many messengers are used to systematically collect and analyze users’ metadata. Threema, on the other hand, generates as little data as technically possible and only stores it as long as absolutely necessary.
Plugins on Android
On Android, separate plugins are required in order to record and send voice messages and to use the QR scanner. If you don’t want to use these features, you don’t need to grant access to your device’s camera or microphone.
To learn more about the differences between Threema and WhatsApp in regard to privacy protection, please consult this comparison: The Threema Advantage