Title:
Dynamic Geolocation Attributes within Functional Encryption Schemes

Description:

The novel attribute-based encryption (ABE) allows a user to encrypt data with fine-grained access control. The data is encrypted with a boolean access formula. In order to be able to decrypt the ciphertext, users need to have a private key. If the attributes in the private key satisfy the boolean formula, then the plaintext is recovered. The special feature of ABE is, that the verification of the attributes is possible without communicating to an external service.

In this thesis a system is described with which ABE can be extended to use dynamic attributes. This allows attributes to be added to an existing private key. For this a server component named attribute authority is introduced. To use this server a client application is necessary. For this purpose an Android application has been developed. The Android application can be used to encrypt and decrypt files. By using dynamic attributes it is now possible to use data that changes often as an attribute. An interesting use for dynamic attributes is location data. To use location data a scheme had to be developed that converts the data into usable ABE attributes. This scheme has also been integrated into the Android application and the server component.

There already was an existing approach to combine location data with ABE. This alternative has also been implemented. Both approaches were evaluated for their advantages and disadvantages. Through the evaluation an important insight was gained. ABE is currently hardly suitable for end users. The time it takes to encrypt and decrypt files on mobile devices is too long. Further improvements to ABE, as well as the increasing capabilities of smartphones, could lead to future situations where this technology is effectively usable.

Supervisor: Sebastian Zickau [1], Dirk Thatmann, Felix Beierle

Type:  Bachelor Thesis

Duration: 4 months