Post Quantum Cryptography (sometimes referred to as a quantum-proof, quantum-safe or quantum-resistant) refers to cryptographic algorithms (usually public-key algorithms) that are thought to be secure against an attack by a quantum computer. PQC is all about preparing for the era of quantum computing by updating existing mathematical-based algorithms and standards. The cryptographic community is working on post-quantum cryptography in order to provide alternatives using hard mathematical problems that cannot be broken by quantum computers. A hybrid scheme is recommended to ease the transition into the post-quantum era. A hybrid scheme is a combination of a traditional and a post-quantum scheme. The resulting scheme is at least as secure as one of the schemes used. In hybrid key establishment, two independent key exchanges are performed one with a traditional scheme like ECDHE and one with a post-quantum scheme like NewHope [1]. In this paper, we propose possible best-fit hybrid digital signatures.
Post Quantum Cryptography (sometimes referred to as a quantum-proof, quantum-safe or quantum-resistant) refers to cryptographic algorithms (usually public-key algorithms) that are thought to be secure against an attack by a quantum computer. PQC is all about preparing for the era of quantum computing by updating existing mathematical-based algorithms and standards. The cryptographic community is working on post-quantum cryptography in order to provide alternatives using hard mathematical problems that cannot be broken by quantum computers. A hybrid scheme is recommended to ease the transition into the post-quantum era. A hybrid scheme is a combination of a traditional and a post-quantum scheme. The resulting scheme is at least as secure as one of the schemes used. In hybrid key establishment, two independent key exchanges are performed one with a traditional scheme like ECDHE and one with a post-quantum scheme like NewHope [1]. In this paper, we propose possible best-fit hybrid digital signatures.
It is assumed that certain mathematical or computational problems which are used in traditional cryptographic schemes are hard to solve for an attacker using today’s computers. But, lots of companies are trying to build quantum computer and in coming few years commercial quantum computer will be in reality. Security of traditional asymmetric cryptographic algorithms can be broken using quantum computers. So, researchers all over the world are planning for transition to post-quantum cryptography. One solution is to build hybrid solution combining both traditional and post-quantum primitives which will provide traditional cryptographic guarantees as well as quantum resistance [1].The best and feasible hybrid solution can be used in the protocols like SSL/TLS, SSH and PGP.
Recent advances in quantum-computing technology have threatened the security of classical cryptographic algorithms. This initiated research on Post-Quantum Cryptography (PQC), and the National Institute of Standards and Technology (NIST) PQC standardization is in progress. Coping with the current situation in which the security of existing cryptographic algorithms is already in question and that of new cryptographic algorithms is not yet certain, there has been active research on hybrid schemes combining two algorithms such that the security of the combined scheme is based on both underlying algorithms. For digital signatures, a naive solution for a hybrid scheme is to simply concatenate a classical signature and a quantum-resistant signature. In this paper, however, we propose a compact hybrid signature construction method that combines two randomized signatures such that the size of the combined signature is shorter than that of naive concatenation. Our construction allows for selective verification, which provides backward compatibility and conformance with existing regulations. We demonstrate the feasibility of the proposed method by combining ECDSA P-256 and Falcon-512, which are representative classical and post-quantum signature schemes, respectively. We prove that the combined signature is existentially unforgeable against an adaptive chosen-message attack, even if one of the underlying signature schemes is completely broken and only the other one remains secure. Through experiments on a desktop PC and Raspberry Pi 3 Model B, we verify that the proposed method effectively reduces the combined signature size with negligible computational overhead. Our experimental results demonstrate the proposed method is also applicable to PQC-PQC combinations.
Public-key cryptography (PKC) provides confidentiality, data integrity, and user authentication. Particularly, nonrepudiation, authentication and integrity of transmitted messages are assured by public-key (PK) signature schemes. Since the presence of a large scale quantum computer would be a real threat to break currently used PK cryptographic algorithms, all security protocols based on the PK cryptographic algorithms are vulnerable to quantum-computer attacks. It needs to investigate possible alternatives, post-quantum cryptography (PQC), believed to be resistant to attacks from both classical and quantum computers. All the traditional PKC should be replaced with PQC for secure communications in post-quantum era. In this work, we evaluate the post-quantum signature schemes in terms of various metrics, performance, signature/key sizes, energy consumption, resistance to implementation attacks and adaptability to Internet protocols. We then investigate their suitability for Internet of Things based on these metrics.
Many companies are working to build a powerful quantum computer.Once quantum computer with large qubits is reality, asymmetric-key cryptosystem will be vulnerable for Shor's algorithm.The transition from one cryptosystem to another is very slow process and consumes many years.National Institute of Standards and Technology (NIST) is working on standardization of post-quantum cryptographic (PQC) algorithms.Security of current PQC algorithms cannot be fully verified today.So, in coming years we need to rely on both traditional algorithms and PQC algorithms.Hybrid mode consisting of one traditional algorithm and one post quantum algorithm is a best solution for smooth migration to quantum-safe cryptosystem.For key exchange, it means using two or more key exchange encapsulation algorithms for generating session key [Meher and Midhunchakkaravarthy (2019)].For authentication, it means using two or more digital signature algorithms [Meher and Midhunchakkaravarthy (2019)].There are number of approaches to combine secret key from traditional algorithm and PQC algorithm to make key encapsulation mechanism quantum-proof.In the paper we propose a new approach of using secret master key generated from one of the KEM algorithm as a salt for hashbased key derivation function (HKDF) to drive session keys from secret master key generated from another KEM algorithm.
Since the security of post-quantum cryptography (PQC) algorithms is based on the hardness of mathematical problems, while the security of quantum key distribution (QKD) relies on the fundamental principles of quantum physics, each approach possesses distinct advantages and limitations that can complement one another. Consequently, recent studies have proposed hybrid schemes that combine QKD and PQC to establish a dual-layered security model. In response to this trend, this study proposes hybrid schemes that integrate QKD with the National Institute of Standards and Technology (NIST) standardized PQC algorithms. These hybrid schemes include two core components: a hybrid QKD-PQC key exchange protocol and a hybrid QKD-PQC digital signature scheme. For the hybrid key exchange protocol, this study combines Module-Lattice-based Key Encapsulation Mechanisms (ML-KEM) with QKD protocols, specifically BB84 and E91, to construct a secure key exchange protocol. In the design of the hybrid digital signature scheme, this study utilizes Module-Lattice-based Digital Signature Algorithms (ML-DSA) and Stateless Hash-based Digital Signature Algorithms (SLH-DSA) to generate signature reconstruction values. These values are verified using confirmation codes transmitted via the BB84 and E91 protocols. The proposed hybrid key exchange protocol is evaluated by examining the shared secret key it produces, particularly with respect to entropy and whether the output is independent and identically distributed (IID). Furthermore, the computation time and message lengths of the proposed hybrid schemes are evaluated.
The accelerated advancements in quantum computing substantially threaten classical cryptographic systems, particularly those that rely on RSA, ECC, and other public key encryption methods. Particularly Shor's method shows how easily conventional cryptographic techniques might be broken; therefore quick development of quantum resistant substitutes is necessary. Rising as a potential answer with cryptographic algorithms meant to resist quantum attacks is post quantum cryptography (PQC). Nonetheless, performance trade-offs, compatibility problems, and the absence of standardized implementations make the shift to completely quantum-safe cryptographic systems very difficult. Hybrid PQC systems that combine conventional and quantum resistant cryptographic mechanisms have been suggested as a workable method for tackling these difficulties so guaranteeing security in the post quantum future. Emphasizing their security, performance, and practical implementations, this review article offers a thorough study of hybrid PQC methods. The resistance of many hybrid cryptographic models including lattice-based, code-based, and multivariate cryptographic techniques against quantum attacks is comprehensively investigated in this work methodologically, we review current PQC hybrid models, evaluate their computing efficiency, and examine security criteria grounded on recent research and standardizing initiatives like those under NIST. Our results show that hybrid PQC models create difficulties in terms of key management, computational overhead, and implementation complexity even if they improve security by reducing risks related with both conventional and quantum attacks. A comparative study shows among several hybrid systems the trade-offs in terms of encryption speed, key sizes, and resource use. Moreover showing the feasibility of PQC hybridizing in IoT, cloud computing, and block chain security are pragmatic uses of PQC hybridizing in which case appropriate protocols are needed for broad acceptance. At last, our work emphasizes the significant contribution hybrid PQC models provide in the transitional period producing a quantum secure environment. To enable basic integration into the present digital infrastructure, future research should focus on improving the efficiency of hybrid cryptosystems, optimizing key exchange mechanisms, and regulating standardization concerns. The findings of this study support the present discussion on post quantum security and provide data for academics and corporate leaders aiming for the next generation of cryptographic solutions. https://doi.org/10.5281/zenodo.17873992