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Revocable quantum timed-release encryption.

Dominique Unruh

Published Jan 1, 2013• 2 citations
OpenAlex

Abstract

Abstract. Timed-release encryption is a kind of encryption scheme that a recipient can decrypt only after a specified amount of time T (assuming that we have a moderately precise estimate of his computing power). A revocable timed-release encryption is one where, before the time T is over, the sender can “give back ” the timed-release encryption, provably loosing all access to the data. We show that revocable timed-release encryption without trusted parties is possible using quantum cryptography (while trivially impossible classically). Along the way, we develop two proof techniques in the quantum random oracle model that we believe may have applications also for other protocols. Finally, we also develop another new primitive, unknown recipient encryption, which allows us to send a message to an unknown/unspecified recipient over an insecure network in such a way that at most one recipient will get the message.

Related papers

Revocable Quantum Timed-Release Encryption

Dominique Unruh

Timed-release encryption is a kind of encryption scheme in which a recipient can decrypt only after a specified amount of time T (assuming that we have a moderately precise estimate of his computing power). A revocable timed-release encryption is one where, before the time T is over, the sender can “give back” the timed-release encryption, provably loosing all access to the data. We show that revocable timed-release encryption without trusted parties is possible using quantum cryptography (while trivially impossible classically). Along the way, we develop two proof techniques in the quantum random oracle model that we believe may have applications also for other protocols. Finally, we also develop another new primitive, unknown recipient encryption , which allows us to send a message to an unknown/unspecified recipient over an insecure network in such a way that at most one recipient will get the message.

Journal of the ACM•Dec 10, 2015•75 citations

A Time-based Secured Framework for Key-Exchange Between Trusted Parties: Quantum-Key Distribution Protocol

Bindu Madavi K P, Krishna Sowjanya K, Neha Patwari +1 more

Cybersecurity attacks are rising day by day due to the explosive growth of the internet. Many encryption techniques and authentication mechanisms also came into existence to avoid or minimize cybersecurity attacks. However, these traditional encryption algorithms are facing new challenges because of quantum computers. Due to their high computational capacity, quantum computers will be able to decipher the messages which are encrypted by the encryption algorithms. To guard against these sophisticated cyber attacks, the Quantum-Key Distribution (QKD) protocol and the Time-Released Encryption(TRE) algorithms are becoming popular. The paper proposes a Time-Based Quantum Key Distribution Protocol (TB-QKD), that enables a secure key exchange and decryption process between two trusted parties on an arbitrary time. The proposed TB-QKD protocol allows the sender and receiver to share the keys securely through the quantum channel with the help of QKD protocol. The algorithm encryption and decryption times for different messages have been observed and presented. Moreover, this protocol also provides a suitable solution that addresses many vulnerabilities that occur in the domain of data security and confidentiality.

IEEE Silchar Subsection Conference (SILCON)•Nov 15, 2024•2 citations

Quantum Time-Lock Puzzles in the Quantum Random Oracle Model

Prabhanjan Ananth, Yao-Ting Lin

A time-lock puzzle allows a sender to hide a message in a puzzle such that recovering the message requires substantially more sequential computation than the time required to generate the puzzle, even when parallel computation is allowed. Applications of time-lock puzzles include timed-release encryption, sealed-bid auctions, electronic voting, fair contract signing, coin flipping, and Byzantine consensus. However, time-lock puzzles are known to be impossible in the classical random oracle model. To overcome the classical barrier, in this work we consider quantum time-lock puzzles, in which the puzzle itself is a quantum state. Our construction in the quantum random oracle model achieves generation in one oracle round, solving in at most $T$ oracle rounds, and security against polynomial-width quantum adversaries of depth $o(T)$ for every polynomially bounded delay $T=T(λ)$, resolving an open problem posed by Mahmoody, Moran, and Vadhan (2011).

quant-pharXiv:2609.38894•Oct 1, 2026•0 citations

Timed Encryption and Its Application.

Shaoquan Jiang

Abstract. In this paper, we propose a new notion of timed encryption, in which the encryption is secure within time t while it is totally insecure after some time T> t. We are interested in the case where t and T are both polynomial. We propose a concrete construction that is provably secure in the random oracle model. We show that it can be generically (although inefficient) constructed from a timed commitment of Boneh and Naor (CRYPTO’00). Finally, we apply this primitive to construct a deniable secure key exchange protocol, where the deniability and secrecy both hold adaptively and the adversary can conduct session state reveal attacks and eavesdropping attacks in the non-eraser model. Our protocol is the first to achieve each of the following properties: adaptive deniability admitting eavesdropping attacks and deniability admitting session state reveal attacks in the non-eraser model. Our protocol is constructed using a timing restriction (inherited from the timed encryption). However, the requirement is rather weak. It essentially asks a user to respond to a ciphertext as soon as possible and hence does not artificially cause any delay. Our usage of timed encryption for the deniability is to use the forceful decryption to obtain the plaintext and hence does not use any random oracle assumption (even if the secrecy proof needs this).

•Jan 1, 2010•0 citations

Two-way unclonable encryption with a vulnerable sender

Daan Leermakers, Boris Škorić

Unclonable Encryption, introduced by Gottesman in 2003 [Quantum Inform. Comput. 3 (2003) 581], is a quantum protocol that guarantees the secrecy of a successfully transferred classical message even when all keys leak at a later time. We propose an Unclonable Encryption protocol with the additional property that the sender’s key material is allowed to leak even in the case of an unsuccessful run. This extra feature makes it possible to achieve secure quantum encryption even when one of the parties is unable to protect its keys against after-protocol theft. Such an asymmetry occurs e.g. in case of server–client scenarios, where the client device is resource constrained and/or located in a hostile environment. Our protocol makes use of a bidirectional quantum channel in a manner similar to the two-way protocol LM05 [Phys. Rev. Lett. 94 (2005) 140501]. Bob sends random qubit states to Alice. Alice flips the states in a way that depends on the message and a shared key, and sends the resulting states back to Bob. Bob recovers Alice’s message by measuring the flips. We prove that our protocol satisfies the definition of unclonable encryption and additionally that the message remains secure even if all of Alice’s keys leak after the protocol. Furthermore, we show that some of the key materials can be safely re-used. Our security proof is formulated in terms of diamond norms, which makes it composable, and allows for noisy quantum channels. We work out the details only for the asymptotics in the limit of long messages. As a side result, we construct a two-way QKD scheme with a high key rate. We show that its key rate is higher than the rate of the two-way QKD scheme LM05 proven by Beaudry et al. [Phys. Rev. A 88 (2013) 062302] for the case of independent channel noise.

arXiv:2010.10827•International Journal of Quantum Information•Mar 1, 2022•1 citation

A new hardware quantum-based encryption algorithm

Zakariya Qawaqneh, Khaled M. Elleithy, Bandar Alotaibi +1 more

Cryptography is entering a new age since the first steps that have been made towards quantum computing, which also poses a threat to the classical cryptosystem in general. In this paper, we introduce a new novel encryption technique and algorithm to improve quantum cryptography. The aim of the suggested scheme is to generate a digital signature in quantum computing. An arbitrated digital signature is introduced instead of the directed digital signature to avoid the denial of sending the message from the sender and pretending that the sender's private key was stolen or lost and the signature has been forged. The onetime pad operation that most quantum cryptography algorithms that have been proposed in the past is avoided to decrease the possibility of the channel eavesdropping. The presented algorithm in this paper uses quantum gates to do the encryption and decryption processes. In addition, new quantum gates are introduced, analyzed, and investigated in the encryption and decryption processes. The authors believe the gates that are used in the proposed algorithm improve the security for both classical and quantum computing. (Against)The proposed gates in the paper have plausible properties that position them as suitable candidates for encryption and decryption processes in quantum cryptography. To demonstrate the security features of the algorithm, it was simulated using MATLAB simulator, in particular through the Quack Quantum Library.

IEEE Long Island Systems, Applications and Technology Conference (LISAT)•May 1, 2014•4 citations
Abstract. Timed-release encryption is a kind of encryption scheme that a recipient can decrypt only after a specified amount of time T (assuming that we have a moderately precise estimate of his computing power). A revocable timed-release encryption is one where, before the time T is over, the sender can “give back ” the timed-release encryption, provably loosing all access to the data. We show that revocable timed-release encryption without trusted parties is possible using quantum cryptography (while trivially impossible classically). Along the way, we develop two proof techniques in the quantum random oracle model that we believe may have applications also for other protocols. Finally, we also develop another new primitive, unknown recipient encryption, which allows us to send a message to an unknown/unspecified recipient over an insecure network in such a way that at most one recipient will get the message.
Timed-release encryption is a kind of encryption scheme in which a recipient can decrypt only after a specified amount of time T (assuming that we have a moderately precise estimate of his computing power). A revocable timed-release encryption is one where, before the time T is over, the sender can “give back” the timed-release encryption, provably loosing all access to the data. We show that revocable timed-release encryption without trusted parties is possible using quantum cryptography (while trivially impossible classically). Along the way, we develop two proof techniques in the quantum random oracle model that we believe may have applications also for other protocols. Finally, we also develop another new primitive, unknown recipient encryption , which allows us to send a message to an unknown/unspecified recipient over an insecure network in such a way that at most one recipient will get the message.
Cybersecurity attacks are rising day by day due to the explosive growth of the internet. Many encryption techniques and authentication mechanisms also came into existence to avoid or minimize cybersecurity attacks. However, these traditional encryption algorithms are facing new challenges because of quantum computers. Due to their high computational capacity, quantum computers will be able to decipher the messages which are encrypted by the encryption algorithms. To guard against these sophisticated cyber attacks, the Quantum-Key Distribution (QKD) protocol and the Time-Released Encryption(TRE) algorithms are becoming popular. The paper proposes a Time-Based Quantum Key Distribution Protocol (TB-QKD), that enables a secure key exchange and decryption process between two trusted parties on an arbitrary time. The proposed TB-QKD protocol allows the sender and receiver to share the keys securely through the quantum channel with the help of QKD protocol. The algorithm encryption and decryption times for different messages have been observed and presented. Moreover, this protocol also provides a suitable solution that addresses many vulnerabilities that occur in the domain of data security and confidentiality.
A time-lock puzzle allows a sender to hide a message in a puzzle such that recovering the message requires substantially more sequential computation than the time required to generate the puzzle, even when parallel computation is allowed. Applications of time-lock puzzles include timed-release encryption, sealed-bid auctions, electronic voting, fair contract signing, coin flipping, and Byzantine consensus. However, time-lock puzzles are known to be impossible in the classical random oracle model. To overcome the classical barrier, in this work we consider quantum time-lock puzzles, in which the puzzle itself is a quantum state. Our construction in the quantum random oracle model achieves generation in one oracle round, solving in at most TTT oracle rounds, and security against polynomial-width quantum adversaries of depth o(T)o(T)o(T) for every polynomially bounded delay T=T(λ)T=T(λ)T=T(λ), resolving an open problem posed by Mahmoody, Moran, and Vadhan (2011).
Abstract. In this paper, we propose a new notion of timed encryption, in which the encryption is secure within time t while it is totally insecure after some time T> t. We are interested in the case where t and T are both polynomial. We propose a concrete construction that is provably secure in the random oracle model. We show that it can be generically (although inefficient) constructed from a timed commitment of Boneh and Naor (CRYPTO’00). Finally, we apply this primitive to construct a deniable secure key exchange protocol, where the deniability and secrecy both hold adaptively and the adversary can conduct session state reveal attacks and eavesdropping attacks in the non-eraser model. Our protocol is the first to achieve each of the following properties: adaptive deniability admitting eavesdropping attacks and deniability admitting session state reveal attacks in the non-eraser model. Our protocol is constructed using a timing restriction (inherited from the timed encryption). However, the requirement is rather weak. It essentially asks a user to respond to a ciphertext as soon as possible and hence does not artificially cause any delay. Our usage of timed encryption for the deniability is to use the forceful decryption to obtain the plaintext and hence does not use any random oracle assumption (even if the secrecy proof needs this).
Unclonable Encryption, introduced by Gottesman in 2003 [Quantum Inform. Comput. 3 (2003) 581], is a quantum protocol that guarantees the secrecy of a successfully transferred classical message even when all keys leak at a later time. We propose an Unclonable Encryption protocol with the additional property that the sender’s key material is allowed to leak even in the case of an unsuccessful run. This extra feature makes it possible to achieve secure quantum encryption even when one of the parties is unable to protect its keys against after-protocol theft. Such an asymmetry occurs e.g. in case of server–client scenarios, where the client device is resource constrained and/or located in a hostile environment. Our protocol makes use of a bidirectional quantum channel in a manner similar to the two-way protocol LM05 [Phys. Rev. Lett. 94 (2005) 140501]. Bob sends random qubit states to Alice. Alice flips the states in a way that depends on the message and a shared key, and sends the resulting states back to Bob. Bob recovers Alice’s message by measuring the flips. We prove that our protocol satisfies the definition of unclonable encryption and additionally that the message remains secure even if all of Alice’s keys leak after the protocol. Furthermore, we show that some of the key materials can be safely re-used. Our security proof is formulated in terms of diamond norms, which makes it composable, and allows for noisy quantum channels. We work out the details only for the asymptotics in the limit of long messages. As a side result, we construct a two-way QKD scheme with a high key rate. We show that its key rate is higher than the rate of the two-way QKD scheme LM05 proven by Beaudry et al. [Phys. Rev. A 88 (2013) 062302] for the case of independent channel noise.
Cryptography is entering a new age since the first steps that have been made towards quantum computing, which also poses a threat to the classical cryptosystem in general. In this paper, we introduce a new novel encryption technique and algorithm to improve quantum cryptography. The aim of the suggested scheme is to generate a digital signature in quantum computing. An arbitrated digital signature is introduced instead of the directed digital signature to avoid the denial of sending the message from the sender and pretending that the sender's private key was stolen or lost and the signature has been forged. The onetime pad operation that most quantum cryptography algorithms that have been proposed in the past is avoided to decrease the possibility of the channel eavesdropping. The presented algorithm in this paper uses quantum gates to do the encryption and decryption processes. In addition, new quantum gates are introduced, analyzed, and investigated in the encryption and decryption processes. The authors believe the gates that are used in the proposed algorithm improve the security for both classical and quantum computing. (Against)The proposed gates in the paper have plausible properties that position them as suitable candidates for encryption and decryption processes in quantum cryptography. To demonstrate the security features of the algorithm, it was simulated using MATLAB simulator, in particular through the Quack Quantum Library.