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Post-quantum cryptography (PQC) refers to novel requirements in asymmetric cryptography, namely key exchange, asymmetric encryption and digital signature. In PQC, the cryptographic computation shall resist not only attacks from classic computers, but also from quantum computers. Still, PQC algorithms are mathematical functions which are implemented conventionally (as software, hardware, etc.). Therefore, regular implementation-level attacks apply. In this paper, we list the challenges associated with the implementation of PQC, in particular vulnerabilities related to side-channel analyses. Some features in PQC, such as modular arithmetic in finite fields, inversions, non-uniform random numbers sampling, or decoding algorithms, are intrinsically hard to evaluate in constant-time. First, we detail the detection and the prevention of leakage arising from conditional control-flow and from conditional access to data structures. Second, we apply the same methodology to data leakage, in the situation where the manipulated data is randomly split in several shares (protection known as "masking"). Conventional detection of vertical leakage is not appropriate in the presence of countermeasures, such as masking. This paper shows that proper implementation of PQC requires knowledge of security evaluation and of secure coding. Owing to the large variety of PQC algorithms (key generation, encapsulation/decapsulation, signature verification/generation), classes (lattice-based, code-based, multivariate, etc.) and their configurations (key size, conforming to IND-CCA or IND-CPA security, etc.), generic methods shall be available. Those are overviewed in this paper, which is intended to provide to the readers with a comprehensive coverage about secure code evaluation and design. [ABSTRACT FROM AUTHOR]

In the era of cloud computing, public key encryption with keyword search (PEKS) is an extremely useful cryptographic tool for searching on encryption data, whose strongest security notion is indistinguishability encryption against chosen ciphertext attack (ind-cca). Adballa et al. presented a transformation from identity based encryption (IBE) to PEKS in the Theory of Cryptography Conference 2010. This paper proposes a new framework of ind-cca secure PEKS in the standard model. Our main technical tool is a newly introduced notion of smooth projective hash function with key mapping, in which the hash key hk is mapped into another mapping projection key mhp besides the classical projection key hp. Finally, we provide an instantiation of our framework based on symmetric eXternal Diffie–Hellman assumption. [ABSTRACT FROM AUTHOR]

Quantum cryptography has developed some fundamental primitives on encryption of quantum data, such as quantum one-time pad and quantum IND (indistinguishability)-security. Compared with other terms in quantum cryptography, quantum obfuscation attracts less attention and is still in its infancy due to its difficulty in implementation and application. In this paper, we define a quantum point function, construct its obfuscation and then demonstrate the validity of applying quantum point obfuscation to quantum symmetric encryption scheme. We rigorously prove that IND-secure quantum symmetric encryption can be realized by quantum point obfuscators. Furthermore, with the properties of combinability or auxiliary inputs, a quantum point obfuscator can implement IND-CPA (indistinguishability under chosen plaintext attack)-secure quantum symmetric encryption or leakage-resilient quantum symmetric encryption, respectively. This work presents new usage of a quantum obfuscator and will complement the theory of quantum obfuscation. [ABSTRACT FROM AUTHOR]