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Ongoing revelations about government agencies snooping on citizens' electronic communications has led to more privacy-awareness among mobile users. Here ZDNet takes a look at 10 apps for Android, iOS, Windows Phone, or BlackBerry that can boost mobile privacy.
Wickr is often compared to Snapchat, but has made security and privacy its key feature.
One of the challenges around privacy for social apps is that 'find friends' features can often undermine it. It's usually done by sucking up a device's contact list to the company's servers where it can be cross-referenced against other users on the service. How it's sent and stored can impact user privacy.
According to Wickr: "if you use Find Friends, the Wickr App will send a disguised representation of your contacts phone number and email address to our servers, at which point our server will check that representation against our database to see whether that contact has an associated Wickr ID."
Text Secure by Open Whisper Systems (OWS) is the messaging sibling of OWS' encrypted voice app RedPhone, and offers encrypted SMS, MMS and instant messaging.
Until recently, Text Secure was purely for encrypted SMS and MMS, but OWC recently introduced new features that bring it up to par with IM apps that communicate over data networks. Users can create private chat groups with the same end to end encryption previously offered with TextSecure SMS chats.
OWS compares it to an encrypted version of Apple's iMessage. TextSecure is a normal SMS/MMS app when communicating with non-TextSecure users, but sends messages encrypted over a data network when both are TextSecure users.
The app is not available for Windows but it's coming soon to iOS. OWS' chief engineer Moxie Marlinspike recent worked with the CyanogenMod team to bring it to the popular custom ROM, which means that Android and soon iOS users can connect securely with friends running it.
As a social app, Text Secure faces the usual privacy challenges in building a social network through find friend features.
"The simplest way to calculate the intersection of registered users and device contacts is to upload all the contacts in the address book to the service, index them, reverse index them, send the client the intersection, and subsequently notify the client when any of those contacts later register," Marlinspike noted in a recent post on the find friend conundrum.
'Encrypted bloom filters' could allow that process to happen privately on the end-user's device, but the file would be impractically large for TextSecure's user base of 10 million, according to Marlinspike.
Meanwhile, the finite possible mobile numbers meant hashes of them could be easily guessed.
"For RedPhone, our user base is still manageable enough (for now) to use the bloom filter technique. For TextSecure, however, we've grown beyond the size where that remains practical, so the only thing we can do is write the server such that it doesn’t store the transmitted contact information, inform the user, and give them the choice of opting out," Marlinspike noted.