This paper defines the conditional constant function problem (CCFP), and for a special case of CCFP, presents a quantum algorithm for solving it efficiently. Such an algorithm enables us to make new evaluations of the quantum security of Feistel block cipher in the case where quantum attackers can only perform online classical queries. Specifically, the chosen-plaintext key recovery attacks on two Feistel block cipher variants, known as Feistel-KF and Feistel-FK, are significantly improved. For Feistel-KF, a 3-round distinguisher based on the special case of CCFP is constructed, and key recovery attacks forr> 3 rounds are proposed. For Feistel-FK, the CCFP based distinguisher covers 4 rounds and the key recovery attacks are applicable forr> 4 rounds. Based on the CCFP solving algorithm, the key recovery attacks can reduce the classical memory complexity from the previous exponentialO(2cn) toO(1), wherec’s are constants. The query complexity of key recovery attacks on Feistel-KF is also significantly reduced fromO(2cn) toO(1). Besides, the CCFP solving algorithm can be extended to reduce the query complexity exponentially in attacking the 2IEM and pEDM constructions. These results indicate that quantum algorithms solving CCFP could be more promising than those solving the period finding problem.

The Industrial Internet of Things (IIoT), as a special form of Internet of Things (IoT), has great potential in realizing intelligent transformation and industrial resource utilization. However, there are security and privacy concerns about industrial data, which is shared on an open channel via sensor devices. To address these issues, many searchable encryption schemes have been presented to provide both data privacy-protection and data searchability. However, due to the use of expensive pairing operations, most previous schemes were inefficient. Recently, a certificateless searchable public-key encryption (CLSPE) scheme was designed by Lu et al. to remove the pairing operation. Unfortunately, we find that Lu et al.’s scheme is vulnerable to user impersonation attacks. To enhance the security, a new pairing-free dual-server CLSPE (DS-CLSPE) scheme for cloud-based IIoT deployment is designed in this paper. In addition, we provide security and efficiency analysis for DS-CLSPE. The analysis results show that DS-CLSPE can resist chosen keyword attacks (CKA) and has better efficiency than other related schemes.

In this work, we give a lattice attack on the ECDSA implementation in the latest version of OpenSSL, which implement the scalar multiplication by windowed Non-Adjacent Form method. We propose a totally different but more efficient method of extracting and utilizing information from the side-channel results, remarkably improving the previous attacks. First, we develop a new efficient method, which can extract almost all information from the side-channel results, obtaining 105.8 bits of information per signature on average for 256-bit ECDSA. Then in order to make the utmost of our extracted information, we translate the problem of recovering secret key to the Extended Hidden Number Problem, which can be solved by lattice reduction algorithms. Finally, we introduce the methods of elimination, merging, most significant digit recovering and enumeration to improve the attack. Our attack is mounted to the {series secp256k1} curve, and the result shows that only 4 signatures would be enough to recover the secret key if the Flush+Reload attack is implemented perfectly without any error,which is much better than the best known result needing at least 13 signatures.

Efficient finite field multiplication is crucial for implementing public key cryptosystem. To achieve this, multipliers using Gaussian normal basis have been widely explored in previous works. In this paper, based on proposed Gaussian normal basis Montgomery (GNBM) representation, a semi-systolic even-type GNBM multiplier is developed. Analysis shows that the proposed architecture saves about 57 percent space complexity and 50 percent time complexity when compared with the only existing semi-systolic even-type GNB multiplier. Moreover, due to properties of regularity and modularity, the proposed multiplier is very suitable for VLSI implementation.

Using the estimates of the exponential sums over Galois rings, we discuss the random properties of the highest level sequences /spl alpha//sub e-1/ of primitive sequences generated by a primitive polynomial of degree n over Z(2/sup e/). First we obtain an estimate of 0, 1 distribution in one period of /spl alpha//sub e-1/. On the other hand, we give an estimate of the absolute value of the autocorrelation function |C/sub N/(h)| of /spl alpha//sub e-1/, which is less than 2/sup e-1/(2/sup e-1/-1)/spl radic/3(2/sup 2e/-1)2/sup n/2/+2/sup e-1/ for h/spl ne/0. Both results show that the larger n is, the more random /spl alpha//sub e-1/ will be.