Proof-of-useful-work (PoUW), an alternative to the widely used proof-of-work (PoW), aims to re-purpose the network’s computing power. Namely, users evaluate meaningful computational problems, e.g., solving optimization problems, instead of computing numerous hash function values as in PoW. A recent approach utilizes the training process of deep learning as “useful work”. However, these works lack security analysis when deploying them with blockchain-based protocols, let alone the informal and over-complicated system design. This work proposes a distributed proof-of-deep-learning (D-PoDL) scheme concerning PoUW’s requirements. With a novel hash-traininßg-hash structure and model-referencing mechanism, our scheme is the first deep learning-based PoUW scheme that enables achieving better accuracy distributively. Next, we introduce a transformation from the D-PoDL scheme to a generic D-PoDL blockchain protocol which can be instantiated with two chain selection rules, i.e., the longest-chain rule and the weight-based blockchain framework (LatinCrypt’ 21). This work is the first to provide formal proofs for deep learning-involved blockchain protocols concerning the robust ledger properties, i.e., chain growth, chain quality, and common prefix. Finally, we implement the D-PoDL scheme to discuss the effectiveness of our design.

In ISO/IEC 20008-2, several anonymous digital signature schemes are specified. Among these, the scheme denoted as Mechanism 6, is the only plain group signature scheme that does not aim at providing additional functionalities. The Intel Enhanced Privacy Identification (EPID) scheme, which has many applications in connection with Intel Software Guard Extensions (Intel SGX), is in practice derived from Mechanism 6. In this paper, we firstly show that Mechanism 6 does not satisfy anonymity in the standard security model, i.e., the Bellare-Shi-Zhang model [CT-RSA 2005]. We then provide a detailed analysis of the security properties offered by Mechanism 6 and characterize the conditions under which its anonymity is preserved. Consequently, it is seen that Mechanism 6 is secure under the condition that the issuer, who generates user signing keys, does not join the attack. We also derive a simple patch for Mechanism~6 from the analysis.

We present a protocol compiler of rational secret-sharing that converts any rational secret-sharing protocol to a protocol with an expected constant-round reconstruction. Our compiler can be applied to protocols for synchronous channels, and preserves a strict Nash equilibrium of the original protocol. Combining with an existing protocol, we obtain the first expected constant-round protocol that achieves a strict Nash equilibrium with the optimal coalition resilience ⌈n2⌉−1⁠, where n is the number of players. Our compiler can be extended to one that preserves the immunity to unexpectedly behaving players. For any constant m≥1⁠, we obtain an expected constant-round protocol that achieves a Nash equilibrium with the optimal coalition resilience ⌈n2⌉−m−1 in the presence of m unexpectedly behaving players. The protocol also achieves a strict Nash equilibrium. As a negative result, we show that if an expected constant-round protocol has immunity m>0⁠, then it cannot achieve a strict Nash equilibrium with the coalition resilience 2. Thus, our protocol with immunity achieves the optimal coalition resilience with respect to both Nash and strict Nash equilibrium.

Abstract In this paper, we present generic transformations, which allow us to be able to convert any signature scheme satisfying the weak existential unforgeability property into one satisfying the strong existential unforgeability property. Different from the previous researches, we consider this kind of transformations in the bounded leakage model, in which part of the secret information could be learned by the adversary. To achieve such transformations, we define a new cryptographic primitive called leakage resilient chameleon hash function and give an instantiation of it based on leakage resilient hard relation. By making use of this new variant of chameleon hash function, we improve the technique proposed by Steinfeld, Pieprzk, and Wang to obtain a generic transformation that works well in the bounded leakage model. Furthermore, we follow the construction of strong one‐time signature by Mohassel to give an instantiation of fully leakage resilient strong one‐time signature based on leakage resilient chameleon hash function. We prove that by combining the fully leakage resilient strong one‐time signature scheme with the transformation proposed by Huang, Wong, and Zhao, we can obtain another transformation that can convert any fully leakage resilient signature scheme that is weakly existentially unforgeable into one that is strongly existentially unforgeable without changing the signing key. Copyright © 2016 John Wiley & Sons, Ltd.

We propose the notion of disavowable public key encryption with non-interactive opening (disavowable PKENO) where, for a ciphertext and a message, the receiver of the ciphertext can issue a proof that the plaintext of the ciphertext is NOT the message, and give a fairly practical construction.

In this paper, in order to control the quality of the embedded content, we propose a new domain, called q-DWT (discrete wavelet transform) for novel and robust image watermarking. We embed the watermark in the low-frequency of q-DWT domain in order to achieve the robustness of watermark. We employ the quantization index modulation (QIM) technique for embedding due to its high robustness and blindness. In our proposed method, the tradeoff of robustness and quality can be controlled by parameter Q of QIM and parameter q of the logarithm function.

In this study, we discuss a display table suitable for collaborative work environments for medical use. Using an interactive stereoscopic display system allows simultaneous observation of accurate stereoscopic images generated from volume data. We further investigate all requirements for design guidelines of the display system, including hardware configuration, rendering software to generate the stereoscopic images, and the interface system to operate the displayed images

A theorem of Markov precisely determines the number r of NEGATION gates necessary and sufficient to compute a system of boolean functions F. For a system of boolean functions on n variables, $r\leq b(n)=\lceil\log_2(n+1)\rceil$. We call a circuit using b(n) NEGATION gates negation-limited. We continue recent investigations into negation-limited circuit complexity, giving both upper and lower bounds. A circuit with inputs x 1 ,..., x n and outputs $\neg x_1, \ldots, \neg x_n$ is called an inverter, for which $r=\lceil\log_2(n+1)\rceil$. Fischer has constructed negation-limited inverters of size O(n 2 log n) and depth O(log n). Recently, Tanaka and Nishino have reduced the circuit size to O(n log 2 n) at the expense of increasing the depth to log 2 n. We construct negation-limited inverters of size O(n log n), with depth only O(log n), and we conjecture that this is optimal. We also improve a technique of Valiant for constructing monotone circuits for slice functions (introduced by Berkowitz). Next, we introduce some lower bound techniques for negation-limited circuits. We provide a 5n+3 log(n+1)-c lower bound for the size of a negation-limited inverter. In addition, we show that for two different restricted classes of circuit, negation-limited inverters require superlinear size.

limited circuit is a combinational circuit Communications for their valuable comments.