To resist the fast algebraic attack and fast selective discrete Fourier transform attacks, spectral immunity of a sequence or a Boolean function was proposed. At the same time, an algorithm to compute the spectral immunity of the binary sequence with odd period N was presented, here N is a factor of 2~n-1, where n is an integer. The case is more complicated when the period is even. In this paper, we compute linear complexity of every orthogonal sequence of a given sequence using Chan-Games algorithm and k- error linear complexity algorithm. Then, an algorithm for spectral immunity of binary sequence with period N=2~n is obtained. Furthermore, the time complexity of this algorithm is proved to be O(n).
Based on the Games-Chan algorithm and StampMartin algorithm, this paper provides some new algorithms to compute the error linear complexity spectrum of binary 2n-periodic se-quences. These new algorithms are clearer and simpler than old algorithms, and they can quickly compute the error linear complexity spectrum of sequences according to different situations. We also discuss such algorithms and give some new results about linear complexity and error linear complexity of sequences.
Algebraic immunity is an important cryptographic property of Boolean functions. In this paper, odd-variable balanced Boolean functions with optimal algebraic immunity are obtained by m-sequence and consequently, we get bases with special constructions of vector space. Furthermore, through swapping some vectors of these two bases, we establish all kinds of odd-variable balanced Boolean functions with optimal algebraic immunity.
In this study, a new methodology based on the Hadamard matrix is proposed to construct quantum Boolean functions f such that f = I2n-2P2n, where I2n is an identity matrix of order 2n and P2n is a projective matrix with the same order as I2n. The enumeration of this class of quantum Boolean functions is also presented.
Multi-proxy signature is a scheme that an original signer delegates his or her signing capability to a proxy group.In the scheme,only the cooperation of all proxy signers in the proxy group can create a signature on behalf of the original signer.Jin and Wen firstly defined the formal security model of certificateless multi-proxy signature(CLMPS) and proposed a concrete CLMPS scheme.However,their construction has three problems:the definition of the strengthened security model is inaccurate,the concrete signature scheme has a security flaw,and the proof of the security is imperfect.With further consideration,a remedial strengthened security model is redefined,and an improved scheme is also proposed,which is existentially unforgeable against adaptively chosen-warrant,chosen-message and chosen-identity attacks in the random oracles.In this condition,the computational Diffie-Hellman(CDH) assumption is used to prove full security for our CLMPS scheme.
Chang et al.[Chin.Phys.623 010305(2014)]have proposed a quantum broadcast communication and authentication protocol.However,we find that an intercept-resend attack can be preformed successfully by a potential eavesdropper,who will be able to destroy the authentication function.Afterwards,he or she can acquire the secret transmitted message or even modify it while escaping detection,by implementing an efficient man-in-the-middle attack.Furthermore,we show a simple scheme to defend this attack,that is,applying non-reusable identity strings.
In this paper, we present a quantum-key-distribution(QKD)-based quantum private query(QPQ) protocol utilizing single-photon signal of multiple optical pulses. It maintains the advantages of the QKD-based QPQ, i.e., easy to implement and loss tolerant. In addition, different from the situations in the previous QKD-based QPQ protocols, in our protocol, the number of the items an honest user will obtain is always one and the failure probability is always zero. This characteristic not only improves the stability(in the sense that, ignoring the noise and the attack, the protocol would always succeed), but also benefits the privacy of the database(since the database will no more reveal additional secrets to the honest users). Furthermore, for the user's privacy, the proposed protocol is cheat sensitive, and for security of the database, we obtain an upper bound for the leaked information of the database in theory.
