The first and best known quantum protocol BB84, whose security is unconditional allows the transmission of a key with a length equal to that of the message. This key used with an encryption algorithm leads to an unbreakable cryptographic scheme. Despite advantages the protocol still can be improved in at least two aspects: its efficiency which is of about 50%, only half of the photons transmitted are used to create the encryption key and the second aspect refers to the communication that takes place on the classic channel, as it must be reduced or even eliminated. The paper presents a method that improves the two aspects of the BB84 protocol by using quantum memory and eight states of polarization. The implementation of both the proposed method and the BB84 protocol was done through a C# application.
The first and best known quantum protocol BB84, whose security is unconditional allows the transmission of a key with a length equal to that of the message. This key used with an encryption algorithm leads to an unbreakable cryptographic scheme. Despite advantages the protocol still can be improved in at least two aspects: its efficiency which is of about 50%, only half of the photons transmitted are used to create the encryption key and the second aspect refers to the communication that takes place on the classic channel, as it must be reduced or even eliminated. The paper presents a method that improves the two aspects of the BB84 protocol by using quantum memory and eight states of polarization. The implementation of both the proposed method and the BB84 protocol was done through a C# application.
Quantum cryptography, the principles of which are based on classical mechanics laws, solves exceptionally the issue of key distribution in classical cryptography. BB84, the first quantum key distribution created by Charles Bennett and Gilles Brassard in 1984 offers unconditional security and allows the transmission of a key with the length equal to the length of the message. According to Vernom, using the key with the above feature once together with an encryption algorithm leads to the formation of a most secure cryptographic system. The paper presents a method for improving the BB84 quantum protocol, using ten states of polarization, quantum memory and direct communication in both directions. The implementation of both the proposed method and the BB84 protocol was done through a C# application.
Quantum Cryptography, the principles of which are based on the laws of quantum mechanics, is a new approach to secure communication. The main advantages of quantum cryptography as opposed to classical cryptography are: unconditional security, the transmission of an encryption key of a length equal to that of the message, the impossibility of creating an identical copy of an unknown quantum state, and the disruption of the quantum system when trying to measure it. BB84 is the first and best known quantum protocol. It was created in 1984 by Charles Bennett and Gilles Brassard and represents a quantum key distribution. The basic idea of the protocol is to encode bits using photon polarization, one bit for each photon. The paper presents an improvement of the protocol by using quantum memory and coding two, three or four bits for each photon, achieving a great efficiency and a higher security level.
Based on quantum computation, Zhou et al proposed a quantum encryption scheme in 2006. Each qubit of the ciphertext is constrained to two pairs of conjugate states. So its implementation is feasible with the existing technology. But it is inefficient since it entails six key bits to encrypt one message bit, and the resulting ciphertext for one message bit consists of three qubits. In addition, its security can not be directly reduced to the well-known BB84 protocol. In this paper, we revisit it using the technique developed in BB84 protocol. The new scheme entails only two key bits to encrypt one message bit. The resulting ciphertext is just composed of two qubits. It saves about a half cost without the loss of security. Moreover, the encryption scheme is probabilistic other than deterministic.
Zhou et al. proposed a quantum encryption scheme based on quantum computation in 2006 [N. Zhou et al., Physica A362 (2006) 305]. Each qubit of the ciphertext is constrained to two pairs of conjugate states. So, its implementation is feasible with the existing technology. But it is inefficient since it entails six key bits to encrypt one message bit, and the resulting ciphertext for one message bit consists of three qubits. In addition, its security cannot be directly reduced to the well-known BB84 protocol. In this paper, we improve it using the technique developed in BB84 protocol. The new scheme entails only two key bits to encrypt one message bit. The resulting ciphertext is just composed of two qubits. It saves about a half cost without the loss of security. Moreover, the new scheme is probabilistic instead of deterministic.
Abstract Zhou et al proposed a quantum encryption scheme based on quantum computation in 2006. Each qubit of the ciphertext is constrained to two pairs of conjugate states. So its implementation is feasible with the existing technology. But it is inefficient since it entails six key bits to encrypt one message bit, and the resulting ciphertext for one message bit consists of three qubits. In addition, its security can not be directly reduced to the well-known BB84 protocol. In this paper, we revisit it using the technique developed in BB84 protocol. The new scheme entails only two key bits to encrypt one message bit. The resulting ciphertext is just composed of two qubits. It saves about a half cost without the loss of security. Moreover, the encryption scheme is probabilistic rather than deterministic. 1
In the modern digital era, cryptographic protocols form the foundation of secure communication, from safeguarding messages to protecting national infrastructure.For years classical encryption techniques served the role of protecting our information; however, due to technological advancements not only in the engineering field but also in the field of physics classical encryption no longer provides reliable and safe security [2][3][4][7].Quantum communication has introduced a fundamentally new paradigm in secure communication, most notably through the BB84 protocol [1].This protocol uses a fundamentally different approach to security that offers unbreakable encryption [10].The advances of the field not only offer protection but also open the possiblity to different approaches to attack [11][15].However, despite its clear advantages, the widespread adoption of the BB84 protocol in everyday communication remains limited by technological and physical barriers [11][15].These challenges include photon loss in transmission, limited key generation rates, short coherence of quantum states, and difficulty integrating these complex systems with existing classical infrastructures [14][17].Furthermore, achieving scalability to support large, complex networks introduces new constraints [14].While these systems can enable fast and long distance transmission, these technologies still remain developmental as well.This paper argues that an overlooked challenge in integrating quantum systems with classical infrastructure is the absence of entanglement in the BB84 protocol, which forces a reliance on classical components that introduce interference and instability [14][18][10].Although the benefits of entanglement-based protocols are recognized in the literature [8][10] [19] the consequences of the BB84's non entangled design remains underexplored [14][17][13].