How Secure Is Textsecure?
How Secure is TextSecure? Tilman Frosch∗y, Christian Mainkay, Christoph Badery, Florian Bergsmay,Jorg¨ Schwenky, Thorsten Holzy ∗G DATA Advanced Analytics GmbH firstname.lastname @gdata.de f g yHorst Gortz¨ Institute for IT-Security Ruhr University Bochum firstname.lastname @rub.de f g Abstract—Instant Messaging has gained popularity by users without providing any kind of authentication. Today, many for both private and business communication as low-cost clients implement only client-to-server encryption via TLS, short message replacement on mobile devices. However, until although security mechanisms like Off the Record (OTR) recently, most mobile messaging apps did not protect confi- communication [3] or SCIMP [4] providing end-to-end con- dentiality or integrity of the messages. fidentiality and integrity are available. Press releases about mass surveillance performed by intelli- With the advent of smartphones, low-cost short-message gence services such as NSA and GCHQ motivated many people alternatives that use the data channel to communicate, to use alternative messaging solutions to preserve the security gained popularity. However, in the context of mobile ap- and privacy of their communication on the Internet. Initially plications, the assumption of classical instant messaging, fueled by Facebook’s acquisition of the hugely popular mobile for instance, that both parties are online at the time the messaging app WHATSAPP, alternatives claiming to provide conversation takes place, is no longer necessarily valid. secure communication experienced a significant increase of new Instead, the mobile context requires solutions that allow for users. asynchronous communication, where a party may be offline A messaging app that claims to provide secure instant for a prolonged time.
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