Quantum data locking is a quantum communication primitive that allows the use of a short secret key to encrypt a much longer message. It guarantees information-theoretical security against an adversary with limited quantum memory. Here we present a quantum data locking protocol that employs pseudorandom circuits consisting of Clifford gates only, which are much easier to implement fault tolerantly than universal gates. We show that information can be encrypted into $n$ -qubit code words using order $n\ensuremath{-}{H}_{\mathrm{min}}(\mathsf{X})$ secret bits, where ${H}_{\mathrm{min}}(\mathsf{X})$ is the min-entropy of the plain text, and a min-entropy smaller than $n$ accounts for information leakage to the adversary. As an application, we discuss an efficient method for encrypting the output of a quantum computer.Quantum data locking is a quantum communication primitive that allows the use of a short secret key to encrypt a much longer message. It guarantees information-theoretical security against an adversary with limited quantum memory. Here we present a quantum data locking protocol that employs pseudorandom circuits consisting of Clifford gates only, which are much easier to implement fault tolerantly than universal gates. We show that information can be encrypted into $n$-qubit code words using order $n\ensuremath{-}{H}_{\mathrm{min}}(\mathsf{X})$ secret bits, where ${H}_{\mathrm{min}}(\mathsf{X})$ is the min-entropy of the plain text, and a min-entropy smaller than $n$ accounts for information leakage to the adversary. As an application, we discuss an efficient method for encrypting the output of a quantum computer.

arXiv:2003.11470Physical Review AMay 24, 20214 citations

Quantum Encryption in Data Communications

Ilga Krūza

Jan 1, 20110 citations

Quantum Symmetric Encryption

Tao Shang

Springer eBooksOct 15, 20240 citations

On the Practical Feasibility of Harvest-Now, Decrypt-Later Attacks

Javier Blanco-Romero, Florina Almenares Mendoza, Carlos García Rubio +2 more

Harvest-now, decrypt-later (HN-DL) attacks threaten today's encrypted communications by archiving ciphertext until a quantum computer can break the underlying key exchange. This paper reframes HN-DL as an economic problem, quantifying adversary costs across Transport Layer Security (TLS) 1.2, TLS 1.3, QUIC, and Secure Shell (SSH) with an open-source testbed that reproduces the full attack sequence. Our model shows that retaining intercepted traffic is economically trivial, shifting the defensive question from whether an adversary can archive to how much decryption will cost. We evaluate protocol configuration strategies that act along two independent cost axes: storage overhead and quantum workload. Beyond the ongoing migration to post-quantum cryptography, these strategies provide defense in depth with current infrastructure. Encrypted Client Hello forces indiscriminate bulk collection, inflating the archive the adversary must retain, while aggressive rekeying and larger key exchange parameters multiply the quantum computations required to recover plaintext. Because storage inflation penalizes both sides while quantum cost inflation targets the adversary alone, rekeying and key size selection offer the strongest defensive levers.Harvest-now, decrypt-later (HN-DL) attacks threaten today's encrypted communications by archiving ciphertext until a quantum computer can break the underlying key exchange. This paper reframes HN-DL as an economic problem, quantifying adversary costs across Transport Layer Security (TLS) 1.2, TLS 1.3, QUIC, and Secure Shell (SSH) with an open-source testbed that reproduces the full attack sequence. Our model shows that retaining intercepted traffic is economically trivial, shifting the defensive question from whether an adversary can archive to how much decryption will cost. We evaluate protocol configuration strategies that act along two independent cost axes: storage overhead and quantum workload. Beyond the ongoing migration to post-quantum cryptography, these strategies provide defense in depth with current infrastructure. Encrypted Client Hello forces indiscriminate bulk collection, inflating the archive the adversary must retain, while aggressive rekeying and larger key exchange parameters multiply the quantum computations required to recover plaintext. Because storage inflation penalizes both sides while quantum cost inflation targets the adversary alone, rekeying and key size selection offer the strongest defensive levers.

arXiv:2603.01091Mar 1, 20260 citations

Benchmarking Post-quantum Cryptography in TLS

Christian Paquin, Douglas Stebila, Goutam Tamvada

Lecture notes in computer scienceJan 1, 2020167 citations

SSL/TLS with Quantum Cryptography

Mario Pivk, Christian Kollmitzer, Stefan Raß

The current standard to exchange a secret key for ensuring secure data transmission within the SSL/TLS protocol is based on Public-Key encryption. This method is only secure as long as the computation power of a potential attacker is limited. So far, the only way to make an unconditional secure key exchange, is to use quantum key distribution (QKD). With the latest figures of sifting key rates provided by NIST, we show which authentic theoretical final key rates are possible. Furthermore we present a modified SSL/TLS protocol, which uses quantum key distribution, in different encryption variants.The current standard to exchange a secret key for ensuring secure data transmission within the SSL/TLS protocol is based on Public-Key encryption. This method is only secure as long as the computation power of a potential attacker is limited. So far, the only way to make an unconditional secure key exchange, is to use quantum key distribution (QKD). With the latest figures of sifting key rates provided by NIST, we show which authentic theoretical final key rates are possible. Furthermore we present a modified SSL/TLS protocol, which uses quantum key distribution, in different encryption variants.

International Conference on Quantum, Nano and Micro Technologies (ICQNM)Feb 1, 20098 citations

n

-qubit code words using order $n\ensuremath{-}{H}_{\mathrm{min}}(\mathsf{X})$ secret bits, where

{H}_{\mathrm{min}}(\mathsf{X})

is the min-entropy of the plain text, and a min-entropy smaller than

n

accounts for information leakage to the adversary. As an application, we discuss an efficient method for encrypting the output of a quantum computer.