Cryptography from tensor problems

We describe a new proposal for a trap-door one-way function. The new proposal belongs to the "multivariate quadratic" family but the trap-door is different from existing methods, and is simpler

Cryptanalysis of the Birational Permutation Signature Scheme over a Non-commutative Ring

In 2008, Hashimoto and Sakurai proposed a new efficient signature scheme, which is a non-commutative ring version of Shamir’s birational permutation signature scheme. Shamir’s scheme is a generalization of the OSS (Ong-Schnorr-Shamir) signature scheme and was broken by Coppersmith et al. using its linearity and commutativity. The HS (Hashimoto-Sakurai) scheme is expected to be secure against the attack of Coppersmith et al. since the scheme is based on the noncommutative structure. In this paper, we propose an attack against the HS scheme. Our proposed attack is practical under the condition that its step size and the number of steps are small. More precisely, we firstly show that the HS scheme is essentially a commutative scheme, that is, the HS scheme can be reduced to some commutative birational permutation signature scheme. Then we apply Patarin-like attack against the commutative birational permutation signature scheme. We discuss efficiency of our attack by using some experimental results. Furthermore the commutative scheme obtained from the HS scheme is the Rainbow-type signature scheme. We also discuss the security of the Rainbow-type signature scheme, and propose an efficient attack against some class of the Rainbow-type signature scheme

Digital Signature Security in Data Communication

Authenticity of access in very information are very important in the current era of Internet-based technology, there are many ways to secure information from irresponsible parties with various security attacks, some of technique can use for defend attack from irresponsible parties are using steganography, cryptography or also use digital signatures. Digital signatures could be one of solution where the authenticity of the message will be verified to prove that the received message is the original message without any change, Ong-Schnorr-Shamir is the algorithm are used in this research and the experiment are perform on the digital signature scheme and the hidden channel scheme.Comment: 6 pages, Paper presented at the International Conference on Education and Technology (ICEduTech2017), Novotel Hotel, Balikpapan, Indonesi

Secure electronic commerce with mobile agents

Online transactions using mobile agents need secure protocols to help the mobile agents to accomplish the transactions initiated by a client in an electronic commerce. However, the mobile agent could encounter hostile environment. For example, a server may compromise the mobile agent and try to obtain private information of the client. A solution to tackle this issue has been proposed. However, the existing solution is implemented using RSA signatures that result in long signatures and heavy workloads for the mobile agent. Mobile agents will migrate from the client to a server and from one server to other servers in order to accomplish the client?s transaction plan. Therefore, it will be interesting to re-tackle this issue. We present a new scheme for secure transactions using mobile agents in potentially hostile environments. This transaction scheme is implemented by using a new undetachable signature scheme. The new undetachable signature protocol utilizes short signatures, which is desirable for low-bandwidth and efficient mobile communications

Secure e-transactions using mobile agents with agent broker

This paper presents an e-transactions protocol using mobile agents. However, when mobile agents travel to a number of servers for searching optimal purchase for the underlying customer, the mobile codes should be protected. We integrate a secure signature algorithm with the e-transaction algorithm to maintain the security. In addition, an agent broker is involved in the algorithm that will help to reduce the communications among the mobile agents, the customer, and the servers. We have presented security and privacy analysis for the proposed protocol

Proposal of a Signature Scheme based on STS Trapdoor

A New digital signature scheme based on Stepwise Triangular Scheme (STS) is proposed. The proposed trapdoor has resolved the vulnerability of STS and secure against both Gröbner Bases and Rank Attacks. In addition, as a basic trapdoor, it is more efficient than the existing systems. With the efficient implementation, the Multivariate Public Key Cryptosystems (MPKC) signature public key has the signature longer than the message by less than 25 %, for example

Construction of the Tsujii-Shamir-Kasahara (TSK) Type Multivariate Public Key Cryptosystem, which relies on the Difficulty of Prime Factorization

A new multivariate public-key cryptosystem (MPKC) with the security based on the difficulty of the prime factoring is proposed. Unlike conventional cryptosystems such as RSA, most MPKCs are expected secure against quantum computers, and their operation of encryption and decryption is expected quick, because they do not need exponential operation. However, their security against quantum computers is very difficult to prove mathematically. We propose a new MPKC based on sequential solution method, assuming the security against von Neumann computers, whose attack seems as difficult as prime factoring. This cryptosystem is applicable to both encryption and signature

Towards a Theory of Symmetric Encryption

Motivée par le commerce et l'industrie, la recherche publique dans le domaine du chiffrement symétrique s'est considérablement développée depuis vingt cinq ans si bien qu'il est maintenant possible d'en faire le bilan. La recherche a tout d'abord progressé de manière empirique. De nombreux algorithmes de chiffrement fondés sur la notion de réseau de substitutions et de permutations ont été proposés, suivis d'attaques dédiées contre eux. Cela a permis de définir des stratégies générales: les méthodes d'attaques différentielles, linéaires et statistiques, et les méthodes génériques fondées sur la notion de boîte noire. En modélisant ces attaques on a trouvé en retour des règles utiles dans la conception d'algorithmes sûrs: la notion combinatoire de multipermutation pour les fonctions élémentaires, le contrôle de la diffusion par des critères géométriques de réseau de calcul, l'étude algébrique de la non-linéarité, ... Enfin, on montre que la sécurité face à un grand nombre de classes d'attaques classiques est assurée grâce à la notion de décorrélation par une preuve formelle. Ces principes sont à l'origine de deux algorithmes particuliers: la fonction CS-Cipher qui permet un chiffrement à haut débit et une sécurité heuristique, et le candidat DFC au processus de standardisation AES, prototype d'algorithme fondé sur la notion de décorrélation