Unclonable Group Identification
We introduce and motivate the concept of unclonable group identification, that provides maximal protection against sharing of identities while still protecting the anonymity of users. We prove that the notion can be realized from any one-way function and suggest a more efficient implementation based on specific assumptions.
Universally Composable Disk Encryption Schemes
We propose a formalization of the security of transparent harddisk-encryption using the universal composability framework. We point out that several commercially available schemes for transparent hard disk encryption are built on principles that limit security, and we propose schemes for disk encryption with passive and active security, respectively. As for the efficiency of the schemes, security against active attacks can be obtained with a constant factor overhead in space and a logarithmic overhead in time. Finally, we also also sketch an actively secure scheme that provides some amount of security, even if the adversary is given temporary access to the internal state of the encryption device used.