In a Ciphertext-Policy Attribute-Based Encryption (CP-ABE) system, decryption privileges are defined over attributes that could be shared by multiple users. If some of the users leak their decryption privileges to the public or to some third party, say for profit gain, a conventional CP-ABE has no tracing mechanism for finding these malicious users out. There are two levels of traceability for ...

Key-homomorphic properties of cryptographic objects have proven to be useful, both from a theoretical as well as a practical perspective. Important cryptographic objects such as pseudorandom functions or (public key) encryption have been studied previously with respect to key-homomorphisms. Interestingly, however, signature schemes have not been explicitly investigated in this context so far. W...

Twofish is a 128-bit block cipher submitted as an AES candidate [SKW+98]. Mirza and Murphy [MM99] recently noted two interesting properties in the Twofish key schedule for 128-bit keys: there is a non-uniform distribution of 128-bit whitening keys, and the 64-bit round subkeys are non-uniformly distributed over each subset of keys that fixes the S-boxes. This paper extends these results and exp...

Cramer, Damgård, and Nielsen [CDN01] show how to construct an efficient secure multiparty computation scheme using a threshold homomorphic encryption scheme that has four properties i) a honest-verifier zero-knowledge proof of knowledge of encrypted values, ii) proving multiplications correct iii) threshold decryption and iv) trusted shared key setup. Naor and Nissim [NN01a] show how to constru...

This paper presents a construction of compactly supported biorthogonal spline wavelets in L2(IR ). In particular, a concrete method for the construction of bivariate compactly supported biorthogonal wavelets from box splines of increasing smoothness is provided. Several examples are given to illustrate the method. Key-Words:multivariate biorthogonal wavelets, multivariate wavelets, box splines,...

This thesis focuses on cryptanalysis techniques and design of block ciphers. In particular, modern analysis methods such as square, boomerang, impossible differential and linear attacks are described and applied to real block ciphers. The first part of this thesis concentrates on the two most relevant modern cryptanalysis techniques: linear and differential cryptanalysis. These and related tech...

The ubiquitin-proteasome system is one of the major protein turnover mechanisms that plays important roles in the regulation of a variety of cellular functions. It is composed of E1 (ubiquitin-activating enzyme), E2 (ubiquitin-conjugating enzyme), and E3 ubiquitin ligases that transfer ubiquitin to the substrates that are subjected to degradation in the 26S proteasome. The Skp1, Cullin, F-box p...

Key-homomorphic properties of cryptographic objects have proven to be useful, both from a theoretical as well as a practical perspective. Important cryptographic objects such as pseudorandom functions or (public key) encryption have been studied previously with respect to key-homomorphisms. Interestingly, however, signature schemes have not been explicitly investigated in this context so far. W...

F-box proteins are substrate adaptors used by the SKP1-CUL1-F-box protein (SCF) complex, a type of E3 ubiquitin ligase complex in the ubiquitin proteasome system (UPS). SCF-mediated ubiquitylation regulates proteolysis of hundreds of cellular proteins involved in key signaling and disease systems. However, our knowledge of the evolution of the F-box gene family in Euarchontoglires is limited. I...

The substitution box (S-box) is found in many block cipher, and it is a very important component. Since the chaotic system has several significant advantageous properties desirable for cryptosystem, the design of S-box using chaos has attracted a great deal of attention in recent years. In this paper, a novel method for designing key-dependent S-boxes based on a four-dimensional hyperchaotic Ch...