ii iii Acknowledgements First of all, I would like to thank Prof. Johannes Buchmann for giving me the opportunity to join his research group, organizing the joint research between TUD and NTT, and promoting this doctor thesis as my supervisor. His suggestions and helpful support improve this work significantly. I would also like to thank Prof. Kouichi Sakurai for accepting the task of the secon...

In the most of scenarios, the trusted center dose not existed. A new verifiable threshold decryption scheme without trusted center was proposed in this paper. In order to publicly verify the identity of decryption member, the scheme forces the member to submit a commitment at the beginning of the process. Moreover, the scheme has several advantages such as cheat-proof and dynamic member revoking.

Authentication protocols are known to be error prone. In this paper we identify non-methodical use of decryption as a typical design feature which is found in many published authentication protocols and is responsible for various problems in these protocols. We reason that authentication protocols can be greatly strengthened by the methodical use of decryption.

A cryptographic contract and enforcement technology would guarantee release of a data decryption key to an authorized party if and only if predetermined contract requirements are satisfied. Threshold secret sharing can be used to eliminate the need for access to the hidden key under normal circumstances. It can also eliminate the liability and burden normally carried by device manufacturers or ...

Abstract We propose an encryption–decryption framework for validating diffraction intensity volumes reconstructed using single-particle imaging (SPI) with X-ray free-electron lasers (XFELs) when the ground truth volume is absent. This conceptual exploits each volumes’ ability to decipher latent variables (e.g. orientations) of unseen sentinel patterns. Using this framework, we quantify novel me...