In this work, we study the intrinsic complexity of black-box Universally Composable (UC) secure computation based on general assumptions. We present a thorough study in various corruption modelings while focusing on achieving security in the common reference string (CRS) model. Our results involve the following: • Static UC secure computation. Designing the first static UC secure oblivious tran...

The current paper studies the probability of differential characteristics for an unkeyed (or with a fixed key) construction. Most notably, it focuses on the gap between two probabilities of differential characteristics: probability with independent S-box assumption, pind, and exact probability, pexact. It turns out that pexact is larger than pind in Feistel network with some S-box based inner f...

UNCLONABLE KEY SEBASTIANUS A. GOORDEN, MARCEL HORSTMANN, ALLARD P. MOSK, BORIS ŠKORIĆ, AND PEPIJN W.H. PINKSE Complex Photonic Systems (COPS), MESA+ Institute for Nanotechnology, University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands Laser Physics and Nonlinear Optics (LPNO), MESA+ Institute for Nanotechnology, University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands Ein...

White-box cryptography has attracted a growing interest from researchers in the last decade. Several white-box implementations of standard block-ciphers (DES, AES) have been proposed but they have all been broken. On the other hand, neither evidence of existence nor proofs of impossibility have been provided for this particular setting. This might be in part because it is still quite unclear wh...

We study the security of key-alternating Feistel ciphers, a class of key-alternating ciphers with a Feistel structure. Alternatively, this may be viewed as the study of Feistel ciphers where the pseudorandom round functions are of the form Fi(x⊕ ki), where ki is the (secret) round key and Fi is a public random function that the adversary is allowed to query in a black-box way. Interestingly, ou...

A one-way permutation (OWP) is one of the most fundamental cryptographic primitives, and can be used as a building block for most of basic symmetric-key cryptographic primitives. However, despite its importance and usefulness, previous black-box separation results have shown that constructing a OWP from another primitive seems hopeless, unless building blocks already achieve “one-way” property ...

Designing systems and services with AI functionality as part of a care experience presents a range of challenges and opportunities. Limitations with sparse or missing data can make algorithmic training difficult, while the opaqueness of some black box methods muddies the process of interpreting outcomes. Human expertise and knowledge need to be carefully integrated at appropriate stages to info...