Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

International Conference on Frontiers of Signal Processing (ICFSP)

Hybrid QKD & PQC Protocols implemented in the Berlin OpenQKD testbed

Marc Geitz, Ronny Döring, Ralf-Peter Braun

Published Oct 23, 2023• 20 citations
Publisher

Abstract

This paper introduces several hybrid protocols based on Quantum Key Distribution (QKD) and Post-Quantum Cryptography (PQC) implemented in the OpenQKD testbed Berlin to improve the security of the QKD nodes. Instead of following the ETSI QKD014 standard of a key management system based on classical security, i.e., RSA authentication and ECC encryption, we implemented a quantum-secure Key Management System based on PQC Key Encapsulation and Signature algorithms. The hardware and the software components of the QKD network authenticate themselves using a PQC trust chain and Pre-Shared Secrets, wherever supported. The communication between QKD nodes, as for the encryption key forwarding process, is hardened by Post-Quantum Cryptography to prevent cryptographic key exposure on intermediate network nodes. Using the two implemented key exchange processes, based on QKD and PQC, applications are able to request any kind of encryption key from the Key Management System and combine them arbitrarily to compute more reliable cryptographic keys.

DOI
10.1109/icfsp59764.2023.10372894

Related papers

Implementation of a Hybrid QKD/PQC Network and Applications

Christoph Döberl, Wolfgang Eibner, Hannes Hübel +7 more

The European Quantum Communication Infrastructure (EuroQCI) initiative is fostering the deployment of national quantum key distribution (QKD) testbeds across the European Union. In this context, we report on the design, implementation, and evaluation of the Austrian testbed, with a particular focus on advances in key management and applicationlevel integration of QKD. First, we introduce a hybrid key management system (KMS) that combines QKD-derived keys in a decentralized architecture with post-quantum authenticated key exchange, enabling end-to-end hybrid keys while reducing trust assumptions in intermediate nodes. Second, we present three QKD-enabled applications: (i) a secure secret-sharing-based storage system leveraging QKD-protected share distribution, (ii) a QKD-integrated extension of Jitsi employing ETSI GS QKD 014 group keys to reduce overhead in multi-party communication, and (iii) a hybrid QKD/PQC WireGuard-based VPN enabling QKD-secured HSM backup operations without requiring modifications to proprietary HSM protocols. Finally, we describe the deployment of these solutions in a national network comprising a four-node metropolitan testbed and a 200 km long-distance link with trusted nodes, and provide performance measurements for both the network and the hybrid KMS. Together, these results demonstrate the feasibility of integrating QKD into heterogeneous applications and hybrid cryptographic infrastructures.

International Conference on Quantum Communications, Networking, and Computing (QCNC)•Apr 6, 2026•0 citations

A PQC and QKD Hybridization for Quantum-Secure Communications

Dominik Marchsreiter, Johanna Sepúlveda

Large quantum computers will be able to break the cryptographic algorithms on which current secure communications rely on. Post-Quantum Cryptography (PQC) and Quantum key distribution (QKD) are two security technologies that show protection capabilities against the latent quantum threat. While PQC relies on different hard mathematical problems to develop a wide variety of cryptographic operations, QKD is based on quantum physics laws to generate and distribute symmetric cryptographic keys through different QKD protocols. These keys can be used by different applications to perform security transformations. QKD still requires authentication to prevent man-in-the-middle attacks. The hybridization of PQC and QKD is an important step for future secure infrastructures, being able to provide long-term security. In this work we propose authenticated QKD approaches that rely on pre-shared keys and hybrid PQC/QKD alternatives and which are able to securely exchange secret QKD keys through authenticated channels. We identify the different configuration alternatives and their parameters, as well as we develop a wide performance evaluation. Results show that pre-shared keys and PQC-based authentication through Dilithium algorithm are the fastest alternatives. Also, we show the potential of the T12 QKD protocol.

Euromicro Conference on Digital System Design (DSD)•Sep 6, 2023•16 citations

The OpenQKD Testbed in Berlin

Ralf-Peter Braun, Marc Geitz

The Berlin OpenQKD Testbed demonstrates the integration of QKD technology into a field installed network infrastructure using a PQC secured key management system and hybrid key exchange protocols to secure communication applications.

Asia Communications and Photonics Conference•Jan 1, 2021•4 citations

Layered Post-Quantum Cryptography: A Dual-Encryption Approach to Mitigate Quantum Threats

Vijay Subhash Katta, DIWAKAR SHRIVASTAVA, Deepanshi Kushwah Deepanshi Kushwah +1 more

The fast development of cyber communications, multimedia distribution, remote working have promoted the demand to transmit sensitive information through secure means in both the public and the private networks. The advent of massive quantum computers is rendering traditional cryptographic algorithms like RSA and Elliptic Curve Cryptography (ECC) insecure because they can crack the classical public-key algorithms like the Shor and Grover algorithms. This brings an immediate need of hybrid cryptographic systems, which integrate classical, quantum, and post-quantum algorithms to provide confidentiality, integrity, authentication, and future security beyond the quantum threat horizon.The paper is a proposal of a Hybrid Quantum-Post-Quantum Cryptographic Framework of transmitting files safely. It starts by aggregating files, which is a process to compress several files, images, videos, and multimedia files that users have chosen into one file to minimize redundancy and ease encryption. The AES-256 encrypted file is in GCM mode and provides confidentiality and integrity of the compressed file.The dual-layer mechanism ensures key establishment security. To begin with, Quantum Key Distribution (QKD) based on the protocols of BB84/E91 allows the Sender and the Receiver to generate a Quantum Secret Key (QSK) by exchanging quantum bits in quantum channel. Constant monitoring of the error rate facilitates automatic eavesdropping detection, and guarantees the keys generation is made when the conditions are secure, as well as the safeguarding of interception and man-in-the-middle attacks.A post-quantum layer is provided to ensure long-term security against quantum cryptanalysis, which uses Kyber, a NIST-approved lattice-based Key Encapsulation Mechanism (KEM). The Receiver creates a key pair of Kyber and disseminates the public key to the Sender. By using encapsulation, the Sender gets a PQC ciphertext and a Shared Secret (SS), with decapsulation on the Receiver side giving ensure that only participants of good faith get the same secret value.The hybridization phase consists of combining the QSK of QKD and SS of Kyber with the help of HKDF-SHA256 to obtain a Final Wrap Key (FWK). AES-GCM encrypts the key of file encryption by wrapping it with FWK which allows a secure and authenticated transfer of the key. The Sender sends four messages: encrypted file, Kyber ciphertext, wrapped AES key and the initialisation vector. At Receiver end, FWK is calculated once again with the help of QSK and SS so that the original data can be decrypted with the help of AES key.The suggested framework provides a defense-in-depth solution based on the combination of quantum security, post-quantum resilience and authenticated symmetric encryption. It can be analyzed that there is a strong resistance to classical and quantum adversaries, scalability, and compatibility with the existing communication networks. This renders the model to be appropriate to secure government communication, military systems, data exchange in healthcare environments, cloud storage and financial infrastructures. Keywords— Quantum Key Distribution (QKD), Post-Quantum Cryptography (PQC), Kyber,Key Encapsulation Mechanism (KEM), HKDF-SHA256, Quantum Secret Key (QSK), GCM Mode.

International Journal of Creative and Open Research in Engineering and Management•Jun 27, 2026•0 citations

Post-Quantum Cryptography for Secure Authentication Key Distribution in QKD Networks

Filip Lauterbach, Lukáš Kapičák, Sergej Jakovlev +3 more

This paper presents a vendor-agnostic architecture for secure pre-shared key (PSK) exchange between Quantum Key Distribution (QKD) nodes, leveraging post-quantum cryptography (PQC) tools. The proposed system combines PQC-OpenVPN and OQS-OpenSSH with USB mass storage emulation and single-board computers (SBCs) to automate the transfer of initial authentication secrets. This design significantly reduces manual intervention and mitigates risks associated with physical key handling. The solution was experimentally validated on IDQ Clavis3 and Cerberis3 devices and is broadly applicable to other QKD platforms that support only USB-based key input. Integration of lattice-based algorithms such as Kyber, Dilithium, and ML-DSA enables encapsulation and authentication of quantum-safe keys. Furthermore, a layered design using VPN and SSH channels provides robust cryptographic isolation for authentication material in transit. The work contributes a reproducible and cost-effective testbed for post-quantum hardened QKD deployments and demonstrates the practical feasibility of combining PQC mechanisms with QKD systems to enhance trust in future quantum-safe infrastructures.

IEEE International Conference on Trust, Security and Privacy in Computing and Communications (TrustCom)•Nov 14, 2025•0 citations

Quantum Cryptography and Key Distribution for Secure Communication in the Post Quantum World

Sai Srinivas Vellela, Pothuguntla Anusha, Nagagopi Raju Vullam +3 more

Quantum computing is posing a serious risk to classical cryptographic tools such as RSA and ECC as sophisticated quantum algorithms are able to crack their mathematical foundation in a time bound that is a a polynomial in the number of repetitions. In this paper, we will describe the process of integrating Post-Quantum Cryptography (PQC) and Quantum Key Distribution (QKD) into a hybrid approach to secure communications in the post-quantum world. The suggested methodology is a combination of the computational efficiency and scalability of PQC and the information-theoretic security and eavesdropping detection abilities of QKD. Simulation observations indicate that PQC-only systems are both faster in generating keys and scalable, but do not have a strong eavesdropping detection. On the other hand, non-conditional security is only a feature of systems based on QKD, but it is also highly overhead and slows down key rate. The hybrid PQC-Q KD model provides a balanced performance, high resilience, high authentication, high confidentiality, and realistic deployability. On balance, this discussion demonstrates that the hybrid approach is better than standalone methods and can provide a strong solution to protect against new quantum threats. The large-scale network protocol can be optimized, resources and further integration with other emerging technologies, such as 5G/6G, IoT or cloud computing, can be directed in future research.

International Conference on Sustainable Communication Networks and Application (ICSCNA)•Oct 15, 2025•2 citations
This paper introduces several hybrid protocols based on Quantum Key Distribution (QKD) and Post-Quantum Cryptography (PQC) implemented in the OpenQKD testbed Berlin to improve the security of the QKD nodes. Instead of following the ETSI QKD014 standard of a key management system based on classical security, i.e., RSA authentication and ECC encryption, we implemented a quantum-secure Key Management System based on PQC Key Encapsulation and Signature algorithms. The hardware and the software components of the QKD network authenticate themselves using a PQC trust chain and Pre-Shared Secrets, wherever supported. The communication between QKD nodes, as for the encryption key forwarding process, is hardened by Post-Quantum Cryptography to prevent cryptographic key exposure on intermediate network nodes. Using the two implemented key exchange processes, based on QKD and PQC, applications are able to request any kind of encryption key from the Key Management System and combine them arbitrarily to compute more reliable cryptographic keys.
The European Quantum Communication Infrastructure (EuroQCI) initiative is fostering the deployment of national quantum key distribution (QKD) testbeds across the European Union. In this context, we report on the design, implementation, and evaluation of the Austrian testbed, with a particular focus on advances in key management and applicationlevel integration of QKD. First, we introduce a hybrid key management system (KMS) that combines QKD-derived keys in a decentralized architecture with post-quantum authenticated key exchange, enabling end-to-end hybrid keys while reducing trust assumptions in intermediate nodes. Second, we present three QKD-enabled applications: (i) a secure secret-sharing-based storage system leveraging QKD-protected share distribution, (ii) a QKD-integrated extension of Jitsi employing ETSI GS QKD 014 group keys to reduce overhead in multi-party communication, and (iii) a hybrid QKD/PQC WireGuard-based VPN enabling QKD-secured HSM backup operations without requiring modifications to proprietary HSM protocols. Finally, we describe the deployment of these solutions in a national network comprising a four-node metropolitan testbed and a 200 km long-distance link with trusted nodes, and provide performance measurements for both the network and the hybrid KMS. Together, these results demonstrate the feasibility of integrating QKD into heterogeneous applications and hybrid cryptographic infrastructures.
Large quantum computers will be able to break the cryptographic algorithms on which current secure communications rely on. Post-Quantum Cryptography (PQC) and Quantum key distribution (QKD) are two security technologies that show protection capabilities against the latent quantum threat. While PQC relies on different hard mathematical problems to develop a wide variety of cryptographic operations, QKD is based on quantum physics laws to generate and distribute symmetric cryptographic keys through different QKD protocols. These keys can be used by different applications to perform security transformations. QKD still requires authentication to prevent man-in-the-middle attacks. The hybridization of PQC and QKD is an important step for future secure infrastructures, being able to provide long-term security. In this work we propose authenticated QKD approaches that rely on pre-shared keys and hybrid PQC/QKD alternatives and which are able to securely exchange secret QKD keys through authenticated channels. We identify the different configuration alternatives and their parameters, as well as we develop a wide performance evaluation. Results show that pre-shared keys and PQC-based authentication through Dilithium algorithm are the fastest alternatives. Also, we show the potential of the T12 QKD protocol.
The fast development of cyber communications, multimedia distribution, remote working have promoted the demand to transmit sensitive information through secure means in both the public and the private networks. The advent of massive quantum computers is rendering traditional cryptographic algorithms like RSA and Elliptic Curve Cryptography (ECC) insecure because they can crack the classical public-key algorithms like the Shor and Grover algorithms. This brings an immediate need of hybrid cryptographic systems, which integrate classical, quantum, and post-quantum algorithms to provide confidentiality, integrity, authentication, and future security beyond the quantum threat horizon.The paper is a proposal of a Hybrid Quantum-Post-Quantum Cryptographic Framework of transmitting files safely. It starts by aggregating files, which is a process to compress several files, images, videos, and multimedia files that users have chosen into one file to minimize redundancy and ease encryption. The AES-256 encrypted file is in GCM mode and provides confidentiality and integrity of the compressed file.The dual-layer mechanism ensures key establishment security. To begin with, Quantum Key Distribution (QKD) based on the protocols of BB84/E91 allows the Sender and the Receiver to generate a Quantum Secret Key (QSK) by exchanging quantum bits in quantum channel. Constant monitoring of the error rate facilitates automatic eavesdropping detection, and guarantees the keys generation is made when the conditions are secure, as well as the safeguarding of interception and man-in-the-middle attacks.A post-quantum layer is provided to ensure long-term security against quantum cryptanalysis, which uses Kyber, a NIST-approved lattice-based Key Encapsulation Mechanism (KEM). The Receiver creates a key pair of Kyber and disseminates the public key to the Sender. By using encapsulation, the Sender gets a PQC ciphertext and a Shared Secret (SS), with decapsulation on the Receiver side giving ensure that only participants of good faith get the same secret value.The hybridization phase consists of combining the QSK of QKD and SS of Kyber with the help of HKDF-SHA256 to obtain a Final Wrap Key (FWK). AES-GCM encrypts the key of file encryption by wrapping it with FWK which allows a secure and authenticated transfer of the key. The Sender sends four messages: encrypted file, Kyber ciphertext, wrapped AES key and the initialisation vector. At Receiver end, FWK is calculated once again with the help of QSK and SS so that the original data can be decrypted with the help of AES key.The suggested framework provides a defense-in-depth solution based on the combination of quantum security, post-quantum resilience and authenticated symmetric encryption. It can be analyzed that there is a strong resistance to classical and quantum adversaries, scalability, and compatibility with the existing communication networks. This renders the model to be appropriate to secure government communication, military systems, data exchange in healthcare environments, cloud storage and financial infrastructures. Keywords— Quantum Key Distribution (QKD), Post-Quantum Cryptography (PQC), Kyber,Key Encapsulation Mechanism (KEM), HKDF-SHA256, Quantum Secret Key (QSK), GCM Mode.
This paper presents a vendor-agnostic architecture for secure pre-shared key (PSK) exchange between Quantum Key Distribution (QKD) nodes, leveraging post-quantum cryptography (PQC) tools. The proposed system combines PQC-OpenVPN and OQS-OpenSSH with USB mass storage emulation and single-board computers (SBCs) to automate the transfer of initial authentication secrets. This design significantly reduces manual intervention and mitigates risks associated with physical key handling. The solution was experimentally validated on IDQ Clavis3 and Cerberis3 devices and is broadly applicable to other QKD platforms that support only USB-based key input. Integration of lattice-based algorithms such as Kyber, Dilithium, and ML-DSA enables encapsulation and authentication of quantum-safe keys. Furthermore, a layered design using VPN and SSH channels provides robust cryptographic isolation for authentication material in transit. The work contributes a reproducible and cost-effective testbed for post-quantum hardened QKD deployments and demonstrates the practical feasibility of combining PQC mechanisms with QKD systems to enhance trust in future quantum-safe infrastructures.
Quantum computing is posing a serious risk to classical cryptographic tools such as RSA and ECC as sophisticated quantum algorithms are able to crack their mathematical foundation in a time bound that is a a polynomial in the number of repetitions. In this paper, we will describe the process of integrating Post-Quantum Cryptography (PQC) and Quantum Key Distribution (QKD) into a hybrid approach to secure communications in the post-quantum world. The suggested methodology is a combination of the computational efficiency and scalability of PQC and the information-theoretic security and eavesdropping detection abilities of QKD. Simulation observations indicate that PQC-only systems are both faster in generating keys and scalable, but do not have a strong eavesdropping detection. On the other hand, non-conditional security is only a feature of systems based on QKD, but it is also highly overhead and slows down key rate. The hybrid PQC-Q KD model provides a balanced performance, high resilience, high authentication, high confidentiality, and realistic deployability. On balance, this discussion demonstrates that the hybrid approach is better than standalone methods and can provide a strong solution to protect against new quantum threats. The large-scale network protocol can be optimized, resources and further integration with other emerging technologies, such as 5G/6G, IoT or cloud computing, can be directed in future research.