Power of a Public Random Permutation and its Application to Authenticated-Encryption

In this paper, we first show that many independent pseudorandom permutations over $\{0,1\}^n$ can be obtained from a single public random permutation and secret $n$ bits. We next prove that a slightly modified IAPM is secure even if the underlying block cipher $F$ is publicly accessible (as a blackbox). We derive a similar result for OCB mode, too. We finally prove that our security bound is tight within a constant factor

Computational Indistinguishability between Quantum States and Its Cryptographic Application

We introduce a computational problem of distinguishing between two specific quantum states as a new cryptographic problem to design a quantum cryptographic scheme that is "secure" against any polynomial-time quantum adversary. Our problem, QSCDff, is to distinguish between two types of random coset states with a hidden permutation over the symmetric group of finite degree. This naturally generalizes the commonly-used distinction problem between two probability distributions in computational cryptography. As our major contribution, we show that QSCDff has three properties of cryptographic interest: (i) QSCDff has a trapdoor; (ii) the average-case hardness of QSCDff coincides with its worst-case hardness; and (iii) QSCDff is computationally at least as hard as the graph automorphism problem in the worst case. These cryptographic properties enable us to construct a quantum public-key cryptosystem, which is likely to withstand any chosen plaintext attack of a polynomial-time quantum adversary. We further discuss a generalization of QSCDff, called QSCDcyc, and introduce a multi-bit encryption scheme that relies on similar cryptographic properties of QSCDcyc.Comment: 24 pages, 2 figures. We improved presentation, and added more detail proofs and follow-up of recent wor

Quantum Fully Homomorphic Encryption With Verification

Fully-homomorphic encryption (FHE) enables computation on encrypted data while maintaining secrecy. Recent research has shown that such schemes exist even for quantum computation. Given the numerous applications of classical FHE (zero-knowledge proofs, secure two-party computation, obfuscation, etc.) it is reasonable to hope that quantum FHE (or QFHE) will lead to many new results in the quantum setting. However, a crucial ingredient in almost all applications of FHE is circuit verification. Classically, verification is performed by checking a transcript of the homomorphic computation. Quantumly, this strategy is impossible due to no-cloning. This leads to an important open question: can quantum computations be delegated and verified in a non-interactive manner? In this work, we answer this question in the affirmative, by constructing a scheme for QFHE with verification (vQFHE). Our scheme provides authenticated encryption, and enables arbitrary polynomial-time quantum computations without the need of interaction between client and server. Verification is almost entirely classical; for computations that start and end with classical states, it is completely classical. As a first application, we show how to construct quantum one-time programs from classical one-time programs and vQFHE.Comment: 30 page

HardIDX: Practical and Secure Index with SGX

Software-based approaches for search over encrypted data are still either challenged by lack of proper, low-leakage encryption or slow performance. Existing hardware-based approaches do not scale well due to hardware limitations and software designs that are not specifically tailored to the hardware architecture, and are rarely well analyzed for their security (e.g., the impact of side channels). Additionally, existing hardware-based solutions often have a large code footprint in the trusted environment susceptible to software compromises. In this paper we present HardIDX: a hardware-based approach, leveraging Intel's SGX, for search over encrypted data. It implements only the security critical core, i.e., the search functionality, in the trusted environment and resorts to untrusted software for the remainder. HardIDX is deployable as a highly performant encrypted database index: it is logarithmic in the size of the index and searches are performed within a few milliseconds rather than seconds. We formally model and prove the security of our scheme showing that its leakage is equivalent to the best known searchable encryption schemes. Our implementation has a very small code and memory footprint yet still scales to virtually unlimited search index sizes, i.e., size is limited only by the general - non-secure - hardware resources

Authenticated public key elliptic curve based on deep convolutional neural network for cybersecurity image encryption application

The demand for cybersecurity is growing to safeguard information flow and enhance data privacy. This essay suggests a novel authenticated public key elliptic curve based on a deep convolutional neural network (APK-EC-DCNN) for cybersecurity image encryption application. The public key elliptic curve discrete logarithmic problem (EC-DLP) is used for elliptic curve Diffie–Hellman key exchange (EC-DHKE) in order to generate a shared session key, which is used as the chaotic system’s beginning conditions and control parameters. In addition, the authenticity and confidentiality can be archived based on ECC to share the (Formula presented.) parameters between two parties by using the EC-DHKE algorithm. Moreover, the 3D Quantum Chaotic Logistic Map (3D QCLM) has an extremely chaotic behavior of the bifurcation diagram and high Lyapunov exponent, which can be used in high-level security. In addition, in order to achieve the authentication property, the secure hash function uses the output sequence of the DCNN and the output sequence of the 3D QCLM in the proposed authenticated expansion diffusion matrix (AEDM). Finally, partial frequency domain encryption (PFDE) technique is achieved by using the discrete wavelet transform in order to satisfy the robustness and fast encryption process. Simulation results and security analysis demonstrate that the proposed encryption algorithm achieved the performance of the state-of-the-art techniques in terms of quality, security, and robustness against noise- and signal-processing attacks

Security analysis of NIST-LWC contest finalists

Dissertação de mestrado integrado em Informatics EngineeringTraditional cryptographic standards are designed with a desktop and server environment in mind, so, with the relatively recent proliferation of small, resource constrained devices in the Internet of Things, sensor networks, embedded systems, and more, there has been a call for lightweight cryptographic standards with security, performance and resource requirements tailored for the highly-constrained environments these devices find themselves in. In 2015 the National Institute of Standards and Technology began a Standardization Process in order to select one or more Lightweight Cryptographic algorithms. Out of the original 57 submissions ten finalists remain, with ASCON and Romulus being among the most scrutinized out of them. In this dissertation I will introduce some concepts required for easy understanding of the body of work, do an up-to-date revision on the current situation on the standardization process from a security and performance standpoint, a description of ASCON and Romulus, and new best known analysis, and a comparison of the two, with their advantages, drawbacks, and unique traits.Os padrões criptográficos tradicionais foram elaborados com um ambiente de computador e servidor em mente. Com a proliferação de dispositivos de pequenas dimensões tanto na Internet of Things, redes de sensores e sistemas embutidos, apareceu uma necessidade para se definir padrões para algoritmos de criptografia leve, com prioridades de segurança, performance e gasto de recursos equilibrados para os ambientes altamente limitados em que estes dispositivos operam. Em 2015 o National Institute of Standards and Technology lançou um processo de estandardização com o objectivo de escolher um ou mais algoritmos de criptografia leve. Das cinquenta e sete candidaturas originais sobram apenas dez finalistas, sendo ASCON e Romulus dois desses finalistas mais examinados. Nesta dissertação irei introduzir alguns conceitos necessários para uma fácil compreensão do corpo deste trabalho, assim como uma revisão atualizada da situação atual do processo de estandardização de um ponto de vista tanto de segurança como de performance, uma descrição do ASCON e do Romulus assim como as suas melhores análises recentes e uma comparação entre os dois, frisando as suas vantagens, desvantagens e aspectos únicos