A classical construction of stream ciphers is to combine several LFSRs and a highly non-linear Boolean function f . Their security is usually studied in terms of correlation attacks, that can be seen as solving a system of multivariate linear equations, true with some probability. At ICISC’02 this approach is extended to systems of higher-degree multivariate equations, and gives an attack in 2 ...

The first part of this paper considers the diamond structures which were first introduced and applied in the herding attack by Kelsey and Kohno [7]. We present a new method for the construction of a diamond structure with 2 chaining values the message complexity of which is O(2 n+d 2 ) . Here n is the length of the compression function used. The aforementioned complexity was (with intuitive rea...

certificateless public key cryptography (cl-pkc) is a useful method in order to solve the problems of traditional public key infrastructure (i. e. large amount of computation, storage and communication cost for managing certificates) and id-based public key cryptography (i. e. key escrow problem), simultaneously. a signcryption scheme is an important primitive in cryptographic protocols which p...

Flame was an advanced malware, used for espionage, which infected computers running a Microsoft Windows operating system. Once a computer in a local network was infected, Flame could spread to the other computers in the network via Windows Update, disguised as a security patch from Microsoft. Windows Update relies on digital signatures to ensure that updates originate from Microsoft. Using an a...

Designated verifier signatures (DVS) allow a signer to create a signature whose validity can only be verified by a specific entity chosen by the signer. In addition, the chosen entity, known as the designated verifier, cannot convince any body that the signature is created by the signer. Multi-designated verifiers signatures (MDVS) are a natural extension of DVS in which the signer can choose m...

Front-running attacks have been a major concern on the blockchain. Attackers launch front-running by inserting additional transactions before upcoming victim to manipulate transaction executions and make profits. Recent studies shown that are prevalent Ethereum blockchain caused millions of US dollars loss. Vulnerable smart contracts, programs invoked transactions, held responsible for attacks....

An efficient Dynamic Provable Data Possession scheme with Public Verifiability and Data Privacy was recently published in ACISP’15. It appears that three attacks menace this scheme. The first one enables the server to store only one block of a file m and still pass the data integrity verification on any number of file blocks. The second attack permits the server to keep the old version of a fil...

At Crypto 2013, Coron, Lepoint, and Tibouchi (CLT) proposed a practical Graded Encoding Scheme (GES) over the integers, which has very similar cryptographic features to ideal multilinear maps. In fact, the scheme of Coron et al. is the second proposal of a secure GES, and has advantages over the first scheme of Garg, Gentry, and Halevi (GGH). For example, unlike the GGH construction, the subgro...