The one-time pad is an encryption technique that is proven to be unbreakable by an eavesdropper. It relies on a single-use secret key shared between a sender and a receiver, whose length is that of the message to be encrypted. The creation of such a key can be achieved through Quantum Key Distribution (QKD), a method based on quantum physics that ensures eavesdroppers' actions can be statistically detected with arbitrarily high probability. It requires a quantum channel for qubit transmission and a classical channel for classical bit transmission. However, the classical channel is generally authenticated by classical means using cryptographic hash functions that are not provably secure. In this paper, we propose for the first time a QKD protocol, based on BB84, that uses quantum error estimation to authenticate both channels. This method relies on the consumption of a smaller pre-shared key, and is provably secure thanks to fundamental results in both information theory and quantum physics.
The one-time pad is an encryption technique that is proven to be unbreakable by an eavesdropper. It relies on a single-use secret key shared between a sender and a receiver, whose length is that of the message to be encrypted. The creation of such a key can be achieved through Quantum Key Distribution (QKD), a method based on quantum physics that ensures eavesdroppers' actions can be statistically detected with arbitrarily high probability. It requires a quantum channel for qubit transmission and a classical channel for classical bit transmission. However, the classical channel is generally authenticated by classical means using cryptographic hash functions that are not provably secure. In this paper, we propose for the first time a QKD protocol, based on BB84, that uses quantum error estimation to authenticate both channels. This method relies on the consumption of a smaller pre-shared key, and is provably secure thanks to fundamental results in both information theory and quantum physics.
Currently many symmetric key cryptographic tools which are known to be quantum-safe. They all share Secret symmetric keys through an untrusted medium which is usually done with public key methods which are prone to quantum attacks. One among the recommended solutions to the key distribution problem is Quantum Key Distribution (QKD). QKD utilizes an authenticated Communication channel along with a quantum communication channel so that a secret key is generated. Whatever may be the protocol to implement proposed QKD, they all need both a quantum channel, and an authenticated classical. OTP (One Time Pad) is used when two parties wish to communications have to share a key called pad. This pad is a randomly generated key and the length of the key should be equal to the message so it can be sent. The proposed QKD parameters that result in almost 35.67% smaller keys for quantum security and an implementation of QKD in network which is publicly available and usable in practice.
Quantum Key Distribution (QKD) is a secret key agreement technique that consists of two parts: quantum transmission and measurement on a quantum channel, and classical post-processing on a public communication channel. It enjoys provable unconditional security provided that the public communication channel is immutable. Otherwise, QKD is vulnerable to a man-in-the-middle attack. Immutable public communication channels, however, do not exist in practice. So we need to use authentication that implements the properties of an immutable channel as well as possible. One scheme that serves this purpose well is the Wegman-Carter authentication (WCA), which is built upon Almost Strongly Universal2 (ASU2) hashing. This scheme uses a new key in each authentication attempt to select a hash function from an ASU2 family, which is then used to generate the authentication tag for a message. The main focus of this dissertation is on authentication in the context of QKD. We study ASU2 hash functions, security of QKD that employs a computationally secure authentication, and also security of authentication with a partially known key. Specifically, we study the following. First, Universal hash functions and their constructions are reviewed, and as well as a new construction of ASU2 hash functions is presented. Second, security of QKD that employs a specific computationally secure authentication is studied. We present detailed attacks on various practical implementations of QKD that employs this authentication. We also provide countermeasures and prove necessary and sufficient conditions for upgrading the security of the authentication to the level of unconditional security. Third, Universal hash function based multiple authentication is studied. This uses a fixed ASU2 hash function followed by one-time pad encryption, to keep the hash function secret. We show that the one-time pad is necessary in every round for the authentication to be unconditionally secure. Lastly, we study security of the WCA scheme, in the case of a partially known authentication key. Here we prove tight information-theoretic security bounds and also analyse security using witness indistinguishability as used in the Universal Composability framework.
Quantum key distribution (QKD) allows two spatially separated parties to securely generate a cryptographic key. The first QKD protocol, published by C. H. Bennett and G. Brassard in 1984 (BB84), describes how this is achieved by transmitting individual qubits and exchanging classical authenticated information. Any attempt to eavesdrop on the protocol introduces errors detectable by the legitimate parties. This Licentiate Thesis studies the recently introduced EEQKD protocol which builds on BB84. In EEQKD, the qubits sent individually in BB84 are entangled and thus not directly available to an eavesdropper who is, in this protocol, provided only one-by-one access to the transmission. The maximal information an eavesdropper can gain using a straightforward intercept-resend (IR) attack, is obtained for a given error rate. The secure key generation rate of EEQKD is estimated in practical scenarios including qubit loss and quantum channel noise. In addition, an exquisite vulnerability is exposed: For a particular setting of qubit entanglement, paradoxically proving most useful in the face of an IR attack, EEQKD reduces to BB84. Part of this research has been published in O. Ahonen et al., Physical Review A 78, 032314 (2008).
Quantum Key Distribution (QKD) protocols, such as BB84, require secure authentication of their classical communication channel to ensure message integrity and authenticity, which is fundamental to successfully distribute unconditionally secure keys and prevent critical vulnerabilities. Traditionally, QKD relies on pre-shared secret keys for this authentication, posing significant scalability challenges. Employing asymmetric encryption methods is also not a viable alternative, as these methods are either vulnerable to quantum computing attacks or lack rigorous security proofs. To address these issues, we propose using the well-established Kerberos authentication protocol, which relies on symmetric cryptography inherently resistant to known quantum attacks, to securely distribute symmetric session keys that authenticate classical communication in QKD systems. We demonstrate the feasibility and practical security advantages of employing Kerberos-generated session keys, inherently resistant to quantum computing attacks, without modifying existing Kerberos workflows, providing a practical quantum-secure solution that leverages existing IT infrastructure.
Quantum cryptography using the BB84 protocol is at the forefront of modern secure communication. This paper emphasizes on BB84 protocol and its role in secure key distribution utilizing the Qiskit libraries in Python to simulate Quantum Key distribution (QKD). This QKD is then applied to the One-Time Pad algorithm for message encryption and decryption. Ensuring data confidentiality and integrity and is difficult due to advanced cyber threats and the potential of quantum computing to undermine traditional cryptographic methods. Current encryption techniques are susceptible to quantum related attacks, risking the decryption of sensitive data. Alice (sender) and Bob (receiver) use classical encryption to communicate but eavesdropper Eve with quantum capabilities, can potentially decrypt their messages. This vulnerability affects critical data security in finance, healthcare, and national security, making robust cryptographic solutions essential for maintaining trust and safety in digital communications. Our work emphasis the utilization of the quantum key generated by employing the BB84 protocol with the help of Qiskit library in python as cipher text in the process of one time pad encryption and decryption. This encrypted data dispatched between the sender and receiver to ensure maximum security, confidentiality and integrity over the period of communication.
One promising way to use quantum information to secure everyday communication is through the distribution of quantum keys. By exchanging a secret key, the Quantum Key Distribution (QKD) approach allows two parties to communicate securely.BB84 protocol is among the most well-known QKD protocols. In this protocol, qubits are exchanged via a quantum channel between the sender and the receiver. This enables them to produce a shared key that is impenetrable to eavesdroppers and illustrate the fundamental ideas of QKD using current simulations and implementations. The results of this study demonstrate that the BB84 protocol is a highly secure QKD technique that has been investigated in great detail and used in a variety of contexts. Additionally, over the enhancements made to the BB84 protocol such as the use of advanced error correction techniques and decoy states to increase its security and usability is discussed. With an emphasis on the BB84 protocol in secure communication technologies, this study offers an extensive analysis of QKD systems overall.