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Development of A BB84-Based Quantum Security System
Prof. Pravin R. Kamble
1
, Shriram Narkhede
2
, Gayatri Bhosale
3
, Shrikant Hundekar
4
Department of Information Technology, Savitribai Phule Pune University, Pune, India
DOI: https://doi.org/10.51583/IJLTEMAS.2026.150600059
Received: 10 June 2026; Accepted: 15 June 2026; Published: 04 June 2026
ABSTRACT
The rapid advancement of quantum computing poses a serious threat to traditional cryptographic systems such
as RSA and Elliptic Curve Cryptography (ECC), which rely on computational difficulty for security. Quantum
algorithms like Shor’s and Grover’s have the potential to break or weaken these methods, putting modern
communication systems at risk. To address this challenge, this work presents a quantum-safe com-munication
framework that combines the BB84 Quantum Key Distribution (QKD) protocol with Post-Quantum
Cryptography (PQC) techniques, aiming to ensure secure data exchange in the presence of quantum-capable
adversaries.
In this system, the BB84 protocol is simulated to enable secure key exchange between two parties over a
virtual quantum channel. The generated key is refined through processes such as basis matching, error
correction, and privacy amplification using SHA-256 to ensure reliability and secrecy. For secur-ing
communication, One-Time Pad (OTP) encryption is used alongside HMAC-SHA3-256 to provide both
confidentiality and message integrity. Additionally, file encryption is handled using the XChaCha20-Poly1305
algorithm, selected for its efficiency and strong protection against potential vulnerabilities like nonce reuse.
To further enhance security, the framework integrates a hybrid key management approach using the Kyber-512
Key Encapsulation Mechanism (KEM) combined with a Key Deriva-tion Function (KDF), merging classical
and quantum-resistant techniques. Experimental results demonstrate the effectiveness of the system, achieving
a Quantum Bit Error Rate (QBER) of 2.5% and successful performance in both message and file en-cryption.
Overall, this work contributes toward the development of practical and resilient communication systems
designed for the emerging quantum era.
Index Terms—Quantum Key Distribution (QKD), BB84 Pro-tocol, Quantum Cryptography, Tensor Networks,
Quantum Sim-ulation, QBER Analysis, Eavesdropping Detection, Secure Com-munication Systems
INTRODUCTION
The rapid progress of quantum computing is creating new challenges for current cryptographic systems.
Techniques such as RSA and Elliptic Curve Cryptography (ECC), which rely on the computational difficulty
of mathematical problems, may become vulnerable as quantum capabilities advance. In particular, algorithms
like Shor’s and Grover’s could signif-icantly weaken these widely used methods, raising concerns about the
security of modern communication networks. This situation emphasizes the need for cryptographic solutions
that can withstand quantum attacks by combining quantum-based key distribution with quantum-resistant
algorithms [12], [17].
Overview of the Proposed System
The proposed quantum-safe communication framework in-tegrates BB84 Quantum Key Distribution (QKD)
with Post-Quantum Cryptography (PQC) to provide a secure way of exchanging both messages and files. In this
approach, users begin by transmitting qubits over a quantum channel using the BB84 protocol, generating an
initial shared key. This key is then improved through processes such as basis comparison and error correction,
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resulting in a reliable secret key shared between the communicating parties [5], [16].
In addition to the quantum-generated key, a post-quantum key is created using a lattice-based algorithm like
Kyber-512. These two keys are combined using a Key Derivation Function (KDF) to produce a hybrid session
key. This layered approach strengthens security by ensuring that even if one component is compromised, the
other continues to provide protection. Simulation-based validation of such hybrid and QKD systems has been
explored in recent frameworks [1], [2], [4].
Encryption Mechanisms
For message transmission, the system uses a one-time pad (OTP) derived from the hybrid key, along with
HMAC-SHA3-256 to verify data integrity and authenticity. For file protection, the XChaCha20-Poly1305
algorithm is employed due to its efficiency and strong resistance to common crypto-graphic weaknesses. The
system utilizes both quantum and classical channels: the quantum channel is responsible for
secure key generation, while the classical channel handles key reconciliation and the transfer of encrypted data.
Such hybrid communication models are increasingly considered essential for building secure and scalable
quantum communication networks [18].
Objectives
The main goals of this research are outlined as follows:
•
To develop a hybrid quantum-secure communication system that combines BB84 Quantum Key Distribu-
tion (QKD) with Post-Quantum Cryptography (PQC), providing stronger protection against both classical
and quantum-based attacks.
•
To ensure secure transmission of chat messages by ap-plying One-Time Pad (OTP) encryption together
with HMAC-SHA3, thereby maintaining confidentiality, data integrity, and authentication throughout the
communica-tion process.
•
To enable secure file transfer using the XChaCha20-Poly1305 algorithm, which offers efficient and authen-
ticated encryption suitable for handling large volumes of data.
•
To validate the effectiveness of the proposed system through experimental analysis, including key
generation, encryption and decryption performance, and evaluation of the Quantum Bit Error Rate (QBER),
which is a key metric in QKD systems.
Overall, the proposed framework is designed to be scalable and robust, offering a practical solution for secure
commu-nication in environments where both classical and quantum threats must be considered. Its hybrid
structure improves fault tolerance and makes it well-suited for next-generation communication systems [18].
LITERATURE REVIEW
This section reviews recent research related to Quantum Key Distribution (QKD) simulation environments,
developments in BB84 protocol modeling, the use of tensor-network techniques for quantum system simulation,
and approaches to security and attack modeling. The literature is structured into focused subsections, each
highlighting how prior studies contribute to and inform the design of the BB84 QKD Simulation System
introduced in this work.
QKD Simulation Frameworks and Network Testbeds
Scalable simulation frameworks and network testbeds are fundamental tools for analyzing Quantum Key
Distribution (QKD) protocols under realistic network conditions. Wu et al. developed a parallel discrete-event
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simulation platform for QKD networks that focuses on scalability and event paral-lelism, allowing efficient
modeling of complex topologies and diverse traffic scenarios [1]. Building on this foundation, Soler et al.
enhanced the NS-3–based simulator QKDNetSim+ by in-corporating more realistic network modules and
refining event management, thereby improving the accuracy of network-layer simulations [4]. Similarly,
Gkouliaras et al. introduced NuQKD, a modular and extensible framework that supports real-time visualization
and allows researchers to integrate new protocol modules and observe their interactive dynamics [2].
Complementing these efforts, Bel et al. offered a compre-hensive perspective on quantum network simulators,
detailing the software toolchains and abstraction layers required for complete end-to-end quantum network
research [18]. Together, these studies reflect a strong community focus on scalability, modularity, and realism in
the development of QKD simulation tools.
BB84 Protocol Studies and Protocol-Level Improvements
The BB84 protocol continues to serve as the foundational model for both educational and experimental QKD
research. Pereira et al. examined the robustness of BB84 by propos-ing modifications that reduce the impact
of source imper-fections—a critical factor when translating from idealized simulations to physical
implementations [16]. Such studies underscore the importance of accounting for hardware limi-tations, including
multi-photon emissions and imperfect state preparation, to ensure meaningful performance and security
evaluation. The BB84 QKD Simulation System introduced in this work incorporates these practical
considerations by allowing users to configure non-ideal conditions and engage in role-based experiments—
representing Alice, Bob, or Eve—to explore how such imperfections influence protocol perfor-mance and
overall system security.
Tensor Network Methods for Quantum Simulation
Tensor-network-based approaches have become indispens-able for simulating quantum circuits and managing
large-scale quantum states efficiently on classical computing resources. Zhao et al. applied tensor-network
edge-cutting techniques to simulate large quantum computations on supercomputers, demonstrating a feasible
method for emulating circuits beyond conventional state-vector limits [7]. In parallel, Mangini et al. and
Melnikov et al. utilized tensor networks for noise characterization and state optimization, showing that these
models not only represent complex noise behaviors but can also act as constructive tools for quantum state
preparation [3], [6]. Further engineering advances from Huang et al. and Pan et al. introduced parallelized tensor
contraction and GPU acceleration, both of which significantly reduce simulation runtime and enhance
scalability [8], [10]. Recent surveys and algorithmic contributions, such as those by D´ıez Garc´ıa and Ma´rquez
Romero and Pastor et al., consolidate current progress and propose new frameworks for parallel tensor-network
algorithms [11], [19]. Together, these studies inform the design of simulation backends that balance high fidelity
with practical computational efficiency.
Modeling Noise, Attacks, and Security Metrics
Accurately modeling quantum noise and eavesdropping strategies is essential for assessing the reliability of
QKD systems. Mangini et al. employed tensor networks to quantify noise, enabling realistic simulation of
imperfect devices and their impact on key security metrics such as the Quantum Bit Error Rate (QBER) [3].
Aizpurua et al. extended this approach by examining tensor-network-based attack models against cryptographic
schemes, revealing new potential vul-nerabilities and emphasizing the importance of integrating adversarial
perspectives into simulator design [12]. Traditional models—such as intercept–resend, partial interception, and
depolarizing channel attacks—remain fundamental for both educational and research-oriented studies, as they
help define QBER thresholds and detection mechanisms [12], [16]. Addi-tional contributions by Thompson et
al. and Masot-Llima et al. enhance the fidelity of noisy-circuit simulations and introduce stabilizer-based tensor
frameworks that can approximate quan-tum dynamics efficiently in specific computational regimes [14], [15].
Scalability and Parallel Algorithms
Scalability remains a major focus in both network-level and circuit-level QKD simulation research. At the
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network scale, Wu et al. and Soler et al. explored parallel discrete-event simulation to handle large numbers of
quantum links and communication sessions [1], [4]. At the computational level, Huang et al. and Pan et al.
focused on optimizing tensor contraction parallelism for circuit simulation, dramatically im-proving runtime
efficiency [8], [10]. Complementary strategies proposed by Pastor et al. use graph-theoretic community de-
tection to partition workloads effectively, allowing simulation processes to scale across distributed computing
resources [19]. Collectively, these techniques illustrate a growing convergence of network-level and tensor-level
parallelism—an integration that enables comprehensive, end-to-end simulation of complex QKD environments.
Integration of Classical Cryptography and Practical Tool-ing
For Quantum Key Distribution (QKD) systems to operate securely in real-world environments, quantum-
generated keys must be effectively integrated with classical cryptographic mechanisms to ensure message
confidentiality and data in-tegrity. Research such as that of Meddeb [?]. illustrates this principle through system-
level implementations in practical settings, including Wi-Fi–based quantum communication sce-narios, where
hybrid stacks and authenticated channels are essential for maintaining secure end-to-end exchanges [5]. Across
the surveyed literature, there is a growing consensus on the importance of incorporating key-derivation
functions, authenticated encryption schemes, and HMAC-based integrity validation into QKD simulators. Such
integration not only enhances realism but also allows these platforms to emulate the behavior of actual
deployment environments. In align-ment with this approach, the BB84 Quantum Key Distribu-tion Simulation
System developed in this work implements HKDF for key derivation, HMAC-SHA3 for authentication, and
XChaCha20-Poly1305 for encryption—together forming a hybrid cryptographic layer that bridges quantum key
gener-ation with classical data protection standards.Research Gaps and Motivation
Although the current body of research provides a strong foundation—covering scalable discrete-event QKD
testbeds [1], [4], modular simulation frameworks [2], tensor-network-based quantum circuit modeling for
enhanced fidelity [3], [7], and comprehensive security and attack analyses [12]—several critical challenges
remain unaddressed. Existing simulators tend to specialize in isolated components, yet few provide end-to-end
educational environments that unify interactive visualization, configurable device imperfections, and balanced
trade-offs between backend accuracy and computational per-formance. Moreover, there is still a notable lack of
frame-works that seamlessly integrate tensor-network computation backends with network-level QKD
simulators, preventing a holistic understanding of hybrid quantum–classical behaviors. Another limitation is the
scarcity of user-centered tools that enable role-based experimentation—where users can adopt the roles of Alice,
Bob, or Eve—while incorporating classical cryptographic primitives for realistic message handling and security
validation.
METHODOLOGY
The proposed system follows a layered security design that combines the inherent security advantages of
quantum key distribution with the strength of modern lattice-based cryptography. By integrating these
approaches, the framework aims to provide protection against both classical and quantum threats [12], [17]. The
methodology is organized into five main phases: Quantum Key Distribution, Classical Post-Processing, Post-
Quantum Key Exchange, Hybrid Key Derivation, and Secure Application Modules [1], [2].
Phase 1: Quantum Key Distribution (BB84)
The process begins at the Alice node, where a random number generator produces a sequence of bits along with
corresponding polarization bases (rectilinear ⊕ or diagonal⊗). Each bit is encoded into a quantum state
(qubit) andtransmitted through a simulated quantum channel [5].
At the Bob node, the received qubits are measured using randomly chosen bases. Due to the nature of quantum
mea-surement, each qubit collapses into a classical bit value, which is stored as part of Bob’s preliminary key.
To evaluate the system’s robustness, an Eve module is introduced to simulate potential eavesdropping. Any
interception attempt disturbs the quantum states, making such attacks detectable [16].
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Phase 2: Classical post-processing
After the quantum transmission phase, both parties commu-nicate over a classical channel to perform basis
reconciliation, keeping only the bits measured using matching bases [1], [5]. Next, the system estimates the
Quantum Bit Error Rate (QBER) by comparing a subset of the shared bits. If the error rate exceeds a
predefined threshold (typically around 11%), the session is considered insecure and is terminated. Otherwise,
the process continues with privacy amplification, where hashing techniques such as SHA-256 are applied
to
reduce any partial information that may have been exposed, resulting in a shorter but more secure key [17].
Phase 3: Post-Quantum Cryptography (PQC) Integration
Alongside the quantum key generation, the system performs a classical key exchange using the Kyber-512
algorithm, a lattice-based Key Encapsulation Mechanism (KEM). This approach is designed to resist attacks
from quantum algo-rithms, providing an additional layer of security [12]. The PQC component ensures reliable
key generation with high agreement rates, complementing the quantum-generated key.
Phase 4: Hybrid Key Establishment
To strengthen overall security, the quantum key and the PQC-generated key are combined using a Key
Derivation Function (KDF), specifically HKDF-SHA256. This hybrid key derivation approach ensures that
even if one component is weakened, the combined key remains secure [1], [2]. This design improves resilience
and makes the system more robust against a wide range of attack scenarios.
Phase 5: Secure Application Modules
The final hybrid key is used across two main application components:
•
Instant Messaging: Messages are secured using One-Time Pad (OTP) encryption, providing strong confi-
dentiality, while HMAC-SHA3-256 is applied to ensure message integrity and authenticity.
•
File Transfer: File encryption is handled using the XChaCha20-Poly1305 algorithm, which offers
efficient authenticated encryption and is well-suited for protecting large data transfers.
This multi-phase approach ensures that the system maintains a balance between theoretical security guarantees
and practical implementation, making it suitable for next-generation secure communication systems [18].
Flow chart: BB84 Quantum Key Distribution Method
Related Work
The increasing capabilities of quantum computing have raised serious concerns about the long-term security of
clas-sical cryptographic systems. Widely used techniques such as RSA and Elliptic Curve Cryptography (ECC)
are particularly vulnerable to quantum algorithms like Shor’s algorithm, which can efficiently solve the
mathematical problems underlying their security. As a result, significant research efforts have shifted toward
developing quantum-resistant solutions, pri-marily through Quantum Key Distribution (QKD) and Post-
Quantum Cryptography (PQC) [12], [17].
The BB84 protocol, originally proposed by Bennett and Brassard, remains one of the most fundamental and
widely analyzed QKD schemes. Numerous studies have evaluated its behavior under realistic conditions,
including noise, photon loss, and hardware imperfections. These works show that BB84 can reliably detect
eavesdropping by monitoring the
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Fig. 1. BB84 Quantum Key Distribution Workflow
Quantum Bit Error Rate (QBER), making it a practical ap-proach for secure key exchange [5], [16]. Simulation
tools and frameworks, such as those based on NS-3 and other quantum network simulators, have further helped
researchers study BB84 in controlled and scalable environments [1], [2], [4].
More recent research has focused on improving the scal-ability and efficiency of QKD systems. Techniques
such as tensor network simulations and advanced modeling approaches allow large quantum systems to be
analyzed with reduced computational overhead. These methods make it possible to evaluate QKD performance
in more realistic and complex net-work scenarios [7], [14]. Additionally, several enhancements to the BB84
protocol have been proposed to address practical challenges, including source imperfections and measurement
inconsistencies [16].
Despite its strong theoretical security, QKD faces practical limitations such as infrastructure complexity, limited
trans-mission range, and challenges in integration with existing communication systems. To overcome these
issues, hybrid approaches that combine QKD with PQC have been widely ex-plored. Lattice-based algorithms
such as Kyber are particularly promising, as they offer resistance to quantum attacks while remaining compatible
with classical computing environments [12].
Hybrid QKD–PQC frameworks have gained attention be-cause they merge the strengths of both paradigms. In
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these systems, keys generated through quantum processes are com-bined with PQC-derived keys using key
derivation techniques, ensuring that the overall system remains secure even if one component is compromised.
This layered approach improves resilience against both classical and quantum adversaries while maintaining
practical deployability [1], [2].
Beyond key exchange, recent work also emphasizes se-cure data transmission using modern symmetric
encryption techniques. Methods such as One-Time Pad (OTP), AES,and XChaCha20-Poly1305 are often
used alongside QKD-generated keys to ensure confidentiality and integrity. Au-thentication mechanisms like
HMAC-SHA3 further strengthen communication by protecting against tampering and replay attacks.
Several studies have also proposed complete end-to-end secure communication frameworks that integrate QKD,
PQC, and modern encryption schemes. These systems typically include components for key management,
session control,
and real-time monitoring of security metrics such as QBER. Experimental results demonstrate
that such integrated solutions are feasible and suitable for applications including secure mes-saging, financial
systems, and government communications [18].
The present work builds on these developments by propos-ing a unified quantum-safe communication
framework that combines BB84 QKD, PQC (Kyber), and advanced encryption techniques. Unlike approaches
that rely solely on a single security mechanism, this work adopts a hybrid strategy to improve overall robustness,
scalability, and real-world appli-cability. Additional features such as simulation support and eavesdropping
detection further enhance the system’s effec-tiveness.
In summary, existing research highlights a clear movement toward hybrid quantum-safe communication models
that in-tegrate both quantum and classical cryptographic techniques. The proposed framework contributes to this
direction by offering a flexible and scalable solution designed to address emerging security challenges in the
quantum computing era.
Comparative Analysis (Compact Table)
TABLE I COMPACT COMPARISON OF TRADITIONAL AND PROPOSED METHODS
DISCUSSION
The comparison indicates that while traditional crypto-graphic techniques are efficient and widely adopted, their
security is increasingly challenged by the emergence of quan-tum computing. Methods such as RSA and ECC,
which rely on computational hardness, may no longer provide adequate protection in the near future.
In contrast, the proposed hybrid approach combines quan-tum key distribution with post-quantum cryptographic
tech-niques to strengthen overall security. The BB84 protocol enables secure key exchange while also allowing
the detection.
Parameter
Traditional
Proposed
Security Basis
Computational
Quantum + PQC
Quantum Resistance
Low
High
Key Distribution
Classical
Quantum (BB84)
Eavesdropping Detection
No
Yes (QBER)
Encryption
RSA, AES
OTP + HMAC
Randomness
Pseudo
True Random
Scalability
High
Moderate
Future Readiness
Limited
Quantum-Safe
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Fig. 2. System architecture diagram of potential eavesdropping through error rate analysis. At the same time,
the inclusion of PQC improves practicality
and ensures compatibility with existing systems. The use of modern
symmetric encryption methods further reinforces both data confidentiality and integrity during communication.
Overall, the results suggest that the proposed system offers a more robust and forward-looking solution. Its
ability to address both current and emerging threats makes it a strong candidate for secure communication in the
evolving landscape of quantum technologies.
SYSTEM DESIGN AND ARCHITECTURE
The proposed system is structured as a modular framework designed to support secure key generation and
protected data transmission. It combines multiple functional layers, including the User Interface and Simulation
Engine, the Core Quantum Engine, the Hybrid Key Management Layer, and the Secure Application Layer. This
layered design helps organize the system efficiently while improving flexibility and scalability [1], [2].
Architectural Overview
The system workflow begins with the GUI Dashboard, where users can configure simulation settings such as
the number of qubits and noise parameters. The Main Simulator serves as the central controller, coordinating
interactions be-tween the sender (Alice), the receiver (Bob), and the optional eavesdropper module (Eve). This
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design ensures smooth com-munication and synchronization across all components [4], [5].
Component Breakdown
The architecture is divided into specialized modules, each handling a specific part of the communication
process:
Core Engine (Tensor Networks): This module uses tensor network techniques, such as Matrix Product States
TABLE II COMPARISON BETWEEN PRIOR WORK AND THE BB84 QKD SIMULATION SYSTEM (THIS PROJECT).
(MPS), to simulate complex quantum states and noise behavior efficiently on classical systems [7], [14].
•
QKD Engine (BB84): Responsible for implementing the BB84 protocol, including qubit preparation,
transmission
Ref.
Focus / Contribution
Approach & Scale
Attack Models / UI
Crypto Integration /
Key Use
[1] X. Wu et
al. (2022)
Scalable QKD
network testbed;
parallel discrete-
event simulation
Discrete-event,
parallel simulation
with emphasis on
scalability and
performance
Basic channel noise; not
focused on varied
eavesdropper (Eve) attack
strategies; minimal,
research-focused metrics
No integrated real-
time one-time pad
(OTP) or file-
encryption
demonstration
[2]
Gkouliaras
et al. (2024)
NuQKD: Modular
simulation
framework
Modular
components;
extensible
simulator
Configurable channel
effects; limited GUI;
framework-oriented with
limited visualization
Simulates key
establishment, but
not a complete
cryptographic stack
[3] Mangini
et al. (2024)
Tensor-network
noise
characterization
Tensor-network-
based noise
modeling; device-
focused
Detailed noise
characterization for NISQ
devices; no real-time
pedagogical UI
Not targeted at
demonstrating
practical key usage
SimulationNoise /Visualization Classicalthrough a simulated quantum channel, and measurement at the
receiver end [16], [17].
•
Key Manager: Combines the quantum-generated key and the PQC-derived key using HKDF-SHA256 to
produce a secure hybrid session key. This approach improves resilience by ensuring that security does not
rely on a single method [1], [2].
•
Crypto Service: Provides essential encryption mecha-nisms, including One-Time Pad (OTP) for secure
mes-saging and XChaCha20-Poly1305 for efficient and au-thenticated file encryption.
•
Eve Simulator: Simulates potential attacks such as intercept-resend strategies and noise injection. These
ac-tions help evaluate system security by analyzing their effect on the Quantum Bit Error Rate (QBER)
[16].
Communication and Sequence Flows
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The system operates through two main communication sequences:
Quantum Key Establishment Sequence:
Initialization: Alice generates a random sequence of
[?], [6]–[11],
[13], [14]
[12],
[20]Aizpurua et al., 2024
[17]–[19](2024–
2025)Tensor-network methods: scalabil-ity, contrac-tion schedul-ing, GPU accelera-tion
Tensor-network-based cryptana-lytic attacks (preprints)
Recent surveys / simula-tors /Tensor networks, edge-cutting, GPU and parallel strategies
Theoretical andexperi-mental attack analysis via TN methodsVaries: surveys, simulator overviews,Some
include noise models and methods for large-circuit simula-tion
Attack modeling at algo-rithmic level (crypt-analysis)Cover noise and attacks at a highResearch-oriented
outputs; not user-facing UIsNo peda-gogical UIMostly research sum-mariesNot focused on direct applica-tion
of keys to OTP/encryption UX
Emphasizes vulnera-bilities ratherthan en-cryption demo
Typically do not bundle a full inter-bits along with corresponding polarization bases using the BB84 protocol
[16].
1)
Quantum Transmission: The encoded qubits are trans-mitted to Bob through a quantum channel. Any inter-
ception attempt introduces detectable disturbances in the form of increased QBER [5].
2)
Basis Sifting: Alice and Bob compare their measure-ment bases over a classical channel and retain only the
matching bits to form a shared key [1].
3)
Security Validation: The system evaluates the QBER. If it exceeds an acceptable threshold (typically
around 11%), the session is terminated to prevent insecure communication [17].
4)
Finalization: If the key is deemed secure, privacy am-plification (e.g., SHA-256) is applied to produce the
final secret key [17].
Authenticated Secure Message Flow:
Message trans-parallel algo-rithms for QKD andparallel algorith-mic
contribu-tionslevel; al-gorithmic solutions and frame-worksactive encryption-demo platformmission follows
a structured process involving encryption, authentication, and delivery. The plaintext is encrypted us-ing a
keystream derived from the hybrid key (OTP-based
This workquantum simula-tion
IntegratedQiskit-Configurable Full in-End-to-approach). To ensure integrity and authenticity, an HMAC-
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SHA3-256 tag is generated using additional metadata such as session identifiers and sequence numbers. On
the receiver side, decryption is only performed after successful verification
(BB84 QKDSimulation System)BB84simula-tion,backedper-photonattackstrate-giesteractive
web UI (Al-end demo: HKDF-of the authentication tag, ensuring that tampered messages are rejected.
real-timesimula-(intercept-ice/Bob/Eve SHA256
visual-ization, attack emula-tion,tion (classical emula-tion), Web-resend, partial inter-cept, depolar-
roles), live QBER
graphs, siftingderiva-tion, OTP
message encryp-System Class Structure
The system design is supported by a structured class ar-chitecture. The SessionManager maintains active
sessions
session lifecycle and crypto-graphic demoSocket real-time sessions, UI for multi-role interac-tionsizing),
channel-noise simula-tion, QBER
analyticsanima-tions, attack sliders, session dash-boardtion, HMAC-SHA3-256,
XChaCha20-
Poly1305 file en-cryptionidentified by unique IDs, while the FileService handles secure
Key Idea: Measurement disturbs quantum states, enabling detection of eavesdropping [17].
QBER Calculation:
QBER =
N
error
N
total
(1)
where
N
error
is the number of mismatched bits and
N
total
is the total number of compared bits.
Condition:
QBER <
11%
⇒
Secure Communication
(2)
2) 2. Post-Quantum Cryptography (Kyber KEM): Kyber is a lattice-based Key Encapsulation Mechanism used
to generate a quantum-resistant key [12].
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Key Generation:
Fig. 3. System flow chart
Encapsulation:
(pk, sk)
=
KeyGen()
(3)
storage and transfer of large files using hybrid encryption keys. Communication between system components is
managed through WebSocket-based interactions, enabling real-time data exchange with minimal delay [18].
Limitations and Assumptions
•
Classical emulation: The current implementation sim-ulates quantum behavior on classical hardware,
which limits scalability compared to real quantum systems. However, tensor network methods help improve
effi-ciency for larger simulations.
•
Authenticated classical channel: The system assumes the availability of a secure classical channel for
tasks such as basis reconciliation. While full authentication mechanisms are not implemented, the
framework allows for future integration.
•
Device imperfections: Real-world imperfections, such as detector inefficiencies and photon losses, are
mod-eled through configurable parameters. However, achiev-ing high accuracy requires calibration with
experimental data, as discussed in prior studies [16].
ALGORITHM USED:
The proposed system implements a hybrid quantum-safe communication framework by integrating Quantum
Key Dis-tribution (QKD), Post-Quantum Cryptography (PQC), and modern symmetric encryption techniques.
The design ensures secure key generation, authentication, and data transmission resistant to both classical and
quantum attacks [12], [17].
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Algorithms Used
1) 1. BB84 Quantum Key Distribution (QKD): The BB84 protocol is used for secure key exchange based on
quantum mechanics. Alice encodes random bits into qubits using ran-dom bases, and Bob measures them using
randomly chosen bases [16].
(c,
K
P
QC
) =
Encaps(pk)
(4)
Decapsulation:
K
P
QC
=
Decaps(c, sk)
(5)
3. Hybrid Key Derivation (HKDF): The final session key is derived by combining QKD and PQC keys:
K
session
= HKDF (K
QKD
⊕
K
P
QC
)
(6)
This ensures enhanced security through a hybrid approach [1], [2].
4. One-Time Pad (OTP) Encryption: OTP provides the-oretically perfect secrecy using XOR operation:
C =
P
⊕
K
(7)
P
= C
⊕
K
(8)
where
P
is plaintext,
C
is ciphertext, and
K
is the key.
5. HMAC-SHA3-256 (Authentication): Ensures message integrity and authenticity:
HMAC
= H(K
⊕
opad, ||,
H(K
⊕
ipad,
||,
m))
(9)
where m is the message and H is the SHA3-256 hash function.
6. XChaCha20-Poly1305 (File Encryption): Used for authenticated encryption of files:
C
=
Enc(K, N, P )
(10)
Tag
=
Auth(K, C)
(11)
where
K
is the key,
N
is nonce,
P
is plaintext, and
C
is ciphertext.
SUMMARY
The proposed system integrates both quantum and classical cryptographic techniques to form a layered and more
robust security framework. The BB84 protocol supports secure key exchange and enables the detection of
eavesdropping through error rate analysis, which has been widely validated in prior research [16], [17]. In
parallel, the use of the Kyber algorithm introduces a quantum-resistant mechanism for key exchange,
strengthening the system against potential quantum-based at-tacks [12].
To protect data during transmission, the system incorpo-rates symmetric encryption techniques such as One-
Time Pad (OTP), HMAC, and XChaCha20. These methods collectively ensure confidentiality, integrity, and
authentication of the trans-mitted information. By combining quantum key distribution with post-quantum and
symmetric cryptographic methods, the framework achieves a balanced and resilient design that is capable of
addressing both current security needs and future challenges arising from advances in quantum computing [1],
[2].
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RESULTS AND DISCUSSION
The performance of the proposed Quantum-Safe Commu-nication System was evaluated through a set of
experiments focusing on key generation, encryption efficiency, and overall system reliability. The findings
demonstrate the practicality of combining BB84 Quantum Key Distribution (QKD) with Post-Quantum
Cryptography (PQC) and modern encryption methods to achieve a secure communication framework.
Quantum Key Distribution Performance
The BB84 protocol was analyzed by transmitting qubits between Alice and Bob under simulated channel
conditions. Key performance indicators included the total number of qubits sent, the rate at which measurement
bases matched, and the resulting Quantum Bit Error Rate (QBER). These metrics provide insight into both the
efficiency of key generation and the system’s ability to detect potential eavesdropping.
Metric
Observed Value
Total Qubits Transmitted
1000
Matching Basis Count
502
Raw Key Length
502 bits
QBER
2.5%
Final Key Length
489 bits
TABLE III EXPERIMENTAL RESULTS OF BB84 QKD (HALF-WIDTH TABLE)
The measured QBER of 2.5% is well below the acceptable threshold of 11%, indicating that the communication
channel remains secure. This low error rate suggests that any potentialeavesdropping or noise has minimal
impact on the transmis-sion. Furthermore, the consistent key generation process high-lights the robustness of
the BB84 protocol, demonstrating its ability to maintain reliable performance even under simulated noisy
conditions.
Post-Quantum Cryptography Performance
The PQC module, implemented using the Kyber-512 algo-rithm, was evaluated for key generation time and
reliability.
Metric
Observed Value
Algorithm Used
Kyber-512
Average Key Generation Time
0.15 sec
Key Agreement Success Rate
100%
Key Size
512 bits
TABLE IV PQC KEY EXCHANGE RESULTS (HALF-WIDTH TABLE)
The results obtained from the PQC module indicate stable and efficient key generation, suggesting its suitability
for integration with QKD-based systems in real-time applications. The consistency in performance highlights its
reliability as a complementary security layer within the overall framework.
Hybrid Key Derivation Analysis
The session key is generated by combining the keys ob-tained from both QKD and PQC using a Key Derivation
Function (HKDF). This hybrid approach strengthens security by ensuring that the compromise of one key source
does not expose the entire system.
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K
session
= HKDF (K
QKD
⊕
K
P
QC
)
(12)
The resulting hybrid key exhibits strong randomness and a uniform distribution, making it well-suited for secure
crypto-graphic applications.
Encryption and Authentication Performance
1)
Message Encryption (OTP + HMAC): The messaging component was evaluated using inputs of varying
lengths to as-sess consistency and performance. The results show that OTP-based encryption effectively
preserves confidentiality, while HMAC-SHA3-256 provides reliable verification of message integrity and
authenticity.
2)
File Encryption (XChaCha20-Poly1305): The file en-cryption module was tested across different file sizes
to measure efficiency and reliability. The findings indicate that the XChaCha20-Poly1305 algorithm
delivers fast and secure encryption, making it suitable for protecting larger data trans-fers without
compromising performance.
End-to-End System Performance
The complete system was evaluated for end-to-end com-munication: The system demonstrated consistent
performance with no failures, confirming its robustness and reliability.
Metric
Observed Value
Messages Tested
20
Encryption Success
100%
Decryption Success
100%
HMAC Verification
100%
TABLE V MESSAGE ENCRYPTION RESULTS (HALF-WIDTH TABLE)
DISCUSSION
The experimental findings highlight the effectiveness of
the proposed hybrid quantum-safe communication
framework. The BB84 protocol consistently produced secure keys with a low Quantum Bit Error Rate
(QBER), indicating strong resistance to eavesdropping attempts. This aligns with existing studies that
demonstrate the reliability of BB84 in detecting unauthorized interception through error analysis [16], [17].
In addition, the integration of Post-Quantum Cryptography (PQC) enhances the system by enabling secure key
exchange over classical channels while remaining resistant to quantum-based attacks [12].
The hybrid key derivation mechanism further strengthens the system by combining independently generated
keys from QKD and PQC. This layered approach ensures that even if one component is weakened, the overall
security of the system is preserved. Such hybrid models have been shown to improve robustness and fault
tolerance in quantum-safe communication architectures [1], [2].
From a data protection perspective, the use of One-Time Pad (OTP) encryption provides strong confidentiality,
while XChaCha20-Poly1305 ensures efficient and authenticated en-cryption for larger data transmissions.
Together, these tech-niques contribute to maintaining both data integrity and per-formance.
When compared to traditional cryptographic approaches, the proposed system offers improved security,
particularly in the context of emerging quantum threats. However, this added security comes with increased
system complexity and computational overhead due to the integration of multiple cryptographic components.
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Overall, the results suggest that the proposed framework achieves a practical balance between security,
efficiency, and scalability. This makes it a promising solution for secure communication in future quantum-
aware environments [18].
CONCLUSION
The implemented BB84-based QKD system successfully demonstrates secure key distribution, effective
detection of eavesdropping, and seamless integration with classical cryptographic techniques for both messaging
and file transfer. These results support its potential for building reliable and quantum-resilient communication
systems.
CONCLUSION AND FUTURE WORK
CONCLUSION
This work presented the design and implementation of a quantum-safe communication system that integrates
Quantum Key Distribution (QKD), based on the BB84 protocol, with Post-Quantum Cryptography (PQC) and
modern symmetric encryption techniques. The proposed hybrid approach ad-dresses the growing security
concerns associated with tra-ditional cryptographic methods in the context of advancing quantum computing
technologies [12], [17].
The BB84 protocol demonstrated consistent performance in generating secure keys, with a low Quantum
Bit Error Rate (QBER), allowing reliable detection of potential eaves-dropping attempts. These results are
consistent with prior studies highlighting the effectiveness of BB84 in secure key exchange [16]. In addition,
the integration of PQC, partic-ularly the Kyber Key Encapsulation Mechanism, provides a quantum-resistant
alternative for classical key exchange, further strengthening the system’s overall security [12]. By combining
QKD and PQC through a hybrid key derivation process, the framework achieves a layered security model that
remains robust even if one component is compromised [1], [2].
For data protection, the use of One-Time Pad (OTP) encryp-tion ensures strong confidentiality, while HMAC-
SHA3-256 provides message integrity and authentication. Furthermore, XChaCha20-Poly1305 enables efficient
and secure file en-cryption, making the system suitable for practical applications involving large data transfers.
These combined mechanisms contribute to a balanced design that supports both security and performance.
Experimental evaluation confirms the reliability and effec-tiveness of the proposed system. The framework
achieved high success rates in key generation, encryption, and decryption, with minimal delays and no
observed authentication fail-ures. Compared to conventional cryptographic approaches, the proposed model
offers improved resilience against quantum-based threats while maintaining practical feasibility through
simulation-based implementation.
Overall, this research demonstrates that integrating quantum and post-quantum techniques can form a strong
foundation for next-generation secure communication systems. The pro-posed framework helps bridge the gap
between theoretical advancements in quantum cryptography and real-world imple-mentation, contributing
toward the development of scalable and future-ready communication infrastructures [18].
FUTURE WORK
While the proposed system shows promising results, several directions can be explored to further enhance its
capabilities:
•
Real-World Quantum Hardware Integration: Future implementations can focus on deploying the system
using actual quantum communication hardware, such as photon sources and detectors, instead of relying
solely on simu-lation environments.
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•
Advanced QKD Protocols: Exploring alternative QKD protocols, such as E91 or Measurement-Device-
Independent QKD (MDI-QKD), could improve security and reduce vulnerabilities related to device
imperfections [17].
•
Improving Key Generation Efficiency: Further opti-mization of error correction and privacy
amplification techniques may help reduce noise effects and increase key generation rates.
•
Scalability and Multi-User Support: Extending the system to support multiple users and larger quantum
networks would enhance its applicability in real-world communication infrastructures.
•
Integration of Additional PQC Algorithms: Incorpo-rating other post-quantum algorithms, such as
NTRU or Dilithium, can provide greater flexibility and strengthen the hybrid security model.
•
Real-Time Application Development: The framework can be extended into practical applications such as
secure messaging or file-sharing platforms with web or mobile interfaces.
•
Performance Optimization: Future work can focus on reducing computational overhead and improving
latency to enable smoother real-time communication.
•
Advanced Security Analysis: Further investigation into side-channel attacks, quantum hacking strategies,
and more sophisticated adversarial models would help en-hance the system’s overall resilience.
In summary, the proposed hybrid quantum-safe communica-tion system provides a strong foundation for ongoing
research in secure communication technologies and supports the de-velopment of practical, scalable solutions
for the emerging quantum era.
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