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cosec >students >Teaching >Winter 2011/2012 

Secure SMS encryption with high usability

Torsten Schröder (University of Bonn)

Thursday 17 November 2011, 15.00, b-it  1.25 (cosec meeting room)

Due to the popularity and the great demand of smart-phones, this presentation is going to introduce a prototype which establishes a connection between the complexity of cryptography and the simple usability of smart-phones. The android operating system, which was used, is widely known and offers a good base for application development. The prototype shows a user-optimized method to send encrypted text messages. The encryption makes use of the elliptic curve Diffie-Hellman key exchange to create a common secret by using an SSL-connection to a key server. Later AES is used for sending the text messages to other users and storing them in a database. The advantage of this combination is that the high reliability against man-in-the-middle attacks (due to the design of SSL) is paired with well-studied asymmetric primitives for key agreement and combined with the small time complexity of the AES for encrypting short messages. Another aspect of implementation is the embedding of this program in a user-friendly graphical user interface and connecting it to services and the contact-provider of the smart-phone.

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