In today’s lecture we study one-time message authentication codes (MACs) which are secure in an information-theoretic sense. We will see that, compared to informationtheoretically secure encryption, significantly better parameters can be achieved. We will also study such MACs in the setting of imperfect randomness, i.e. when the secret key is not drawn from the uniform distribution but rather i...

Message authentication codes (MACs) based on universal hash-function families are becoming increasingly popular due to their fast implementation. In this paper, we investigate a family of universal hash functions that has been appeared repeatedly in the literature and provide a detailed algebraic analysis for the security of authentication codes based on this universal hash family. In particula...

We consider Muller asynchronous cellular automata running on infinite dags over distributed alphabets. We show that they have the same expressive power as the existential fragment of a monadic secondorder logic featuring a first-order quantifier to express that there are infinitely many elements satisfying some property. Our result is based on an extension of the classical Ehrenfeucht-Fräıssé g...

Correct authenticated decryption requires the receiver to buffer the decrypted message until the authenticity check has been performed. In high-speed networks, which must handle large message frames at low latency, this behavior becomes practically infeasible. This paper proposes CCA-secure on-line ciphers as a practical alternative to AE schemes since the former provide some defense against ma...

A Message Authentication Code (MAC) computes for each (arbitrarily long) message m and key k a short authentication tag which is hard to forge when k is unknown. One of the most popular ways to process m in such a scheme is to use some variant of AES in CBC mode, and to derive the tag from the final ciphertext block. In this paper we analyze the security of several proposals of this type, and s...

A peer-to-peer (P2P) file sharing network provides a resource sharing platform for Internet users. To increase higher-degree resource sharing, heterogeneous P2P file sharing networks need a way to collaborate and communicate with each other. Based on the approach of interconnecting heterogeneous P2P file sharing networks, users on one P2P file sharing network can share resources and search data...

Universal hash functions (UHFs) have been extensively used in the design of cryptographic schemes. If we consider the related-key attack (RKA) against these UHF-based schemes, some of them may not be secure, especially those using the key of UHF as a part of the whole key of scheme, due to the weakness of UHF in the RKA setting. In order to solve the issue, we propose a new concept of related-k...

Let IF be a finite field and suppose that a single element of IF is used as an authenticator (or tag). Further, suppose that any message consists of at most L elements of IF. For this setting, usual polynomial based universal hashing achieves a collision bound of (L− 1)/|IF| using a single element of IF as the key. The well-known multi-linear hashing achieves a collision bound of 1/|IF| using L...

In 1998 C. Cachin proposed an information-theoretic approach to steganography. In particular, in the framework of this approach the so-called perfectly secure stegosystem was defined, where messages that carry and do not carry hidden information are statistically indistinguishable. There was also described a universal steganographic system, for which this property holds only asymptotically, as ...

This paper presents a machine learning strategy that tackles distributed optimization task in wireless network with an arbitrary number of randomly interconnected nodes. Individual nodes decide their optimal states coordination among other through varying backhaul links. poses technical challenge universal policy robust to random topology the network, which has not been properly addressed by co...