Encryption Research Articles

Two-step Fourier single-pixel imaging for secure and efficient hidden information transmission

In the rapidly evolving field of optical information security, single-pixel imaging (SPI) has emerged as a promising technique for hidden information transmission. However, traditional SPI methods face significant challenges, including the need for excessive modulation patterns and the vulnerability of encrypted information during transmission. Furthermore, the field lacks efficient methods to reconstruct both plaintext and ciphertext images from the same set of single-pixel measurements. Here, we propose a novel and efficient encryption strategy for Fourier single-pixel imaging (FSPI) that addresses these critical challenges. Our approach integrates two key innovations: a two-step Fourier-total variation conjugate gradient descent (F-TVCGD) method and a dual-key decryption mechanism. The F-TVCGD method significantly reduces the number of modulation patterns required for image reconstruction, enhancing efficiency and minimizing data redundancy. Our dual-key mechanism enables the reconstruction of both plaintext and ciphertext images from a single set of single-pixel measurements using different decryption keys, significantly enhancing security without compromising efficiency. The incorporation of Fourier symmetric patterns improves the convergence robustness of the symmetric gradient descent (SGD) algorithm, leading to superior performance under challenging conditions such as sparse sampling and noise attacks. Numerical simulations and optical experiments validate our method's improvements in both accuracy and security compared to traditional approaches. Our findings demonstrate that the proposed F-TVCGD and SGD strategies effectively address the challenges of excessive modulation patterns and information vulnerability in FSPI.

Optical phase image encryption using stokes parameters and singular value decomposition

Abstract In this paper, we propose an optical asymmetric phase image encryption method in which the vectorial light field is used to encode the data. In transverse plane, the vectorial light field has spatially varying polarization distributions where we are allowed to have a greater number of degrees of freedom. In this scheme, the input image is first phase encoded and then modulated by a phase encrypting key, synthesized from the speckles obtained by the scattering of Hermite–Gaussian beams. The modulated image is further processed using fractional Fourier transform with a specific order (α). A pixel scrambling operator is utilized to increase the randomness to further enhance the security and singular value decomposition approach is employed to add the nonlinearity in the encryption process. Now, the stokes parameters, i.e. S 1 and S 2 are calculated using the light intensities correspond to different polarizations. S 1 is used as the encrypted image for transmission and S 2 is reserved as one of the private decryption keys. The robustness of the proposed technique is tested against various existing attacks, such as known plaintext attack, chosen plaintext attack, and contamination attacks. Numerically simulated results validate the effectiveness and efficiency of the proposed method.

Lightweight Cryptography using Pairwise key generation and malicious node detection in large UAV

Data security is very essential concern in network data transmission between various sensor nodes. Data encryption is the only way to provide security to sensitive information during the transmission. Various researchers have developed the different encryption techniques with heterogeneous encryption and decryption keys. Nevertheless, the standard does not include guidance for the administration, storage, or distribution of encryption keys. Various researchers proposed key management techniques, but those methods still generate high overhead during data communication. To eliminate such problems, we suggest lightweight key encryption using pairwise cryptography and malicious node detection from large UAVs. The proposed encryption algorithm compresses the cypher data, reducing the network overhead, and detecting malicious nodes provides higher security from internal and external intruders. In extensive experimental analysis, our simulation obtains better results than existing systems. That enhances around 7-9% throughput with other QoS parameters.

An application-layer plausibly deniable encryption system for wearable devices

Wearable devices especially smartwatches are widely used in our daily life. With their increased use, a large amount of sensitive data are collected, stored, and managed in those devices. To protect sensitive data, encryption is often used but, traditional encryption is vulnerable to a novel coercive attack in which the adversary can capture the device’s user and coerce the user to disclose the decryption key. To defend against the coercive attack, Plausibly Deniable Encryption (PDE) has been designed which can allow the victim user to deny the existence of hidden sensitive data. The PDE systems have been explored broadly for smartphones. However, the PDE systems which are suitable for wearable devices are still missing in the literature. In this work, we have designed MobiWear, the first PDE system specifically designed for wearable devices. By leveraging PDE, image steganography as well as watermarking, MobiWear ensures plausible deniability and can be easily deployed at the application layer. In addition, MobiWear relies on sensors equipped with the wearable devices to enter passwords, accommodating the wearable devices which have small-size screens and are inconvenient for entering plaintext. Security analysis and experimental evaluation using a real-world prototype (ported to an LG G smartwatch) show that MobiWear can ensure the deniability with a small computational overhead as well as a tiny degradation of the perceived quality of the image.

GFLE: a low-energy lightweight block cipher based on a variant of generalized Feistel structure

Low-energy lightweight block ciphers are essential for applications with extremely resource-constrained to reduce energy and maintain security. The trade-off between diffusion property and area is a widely studied issue in the design of low-energy block ciphers. In this paper, a low-energy lightweight block cipher named as GFLE is presented. The core cipher of GFLE uses a variant of the Generalized Feistel Structure (GFS) with 4-branch, which combines the Type-II GFS with the simplified Lai-Massey. The DRmax of GFLE has a one-round improvement over the Type-II GFS optimized by Suzaki et al and the security margin is achieved in a shorter number of rounds. Moreover, an S-box with low-energy and good cryptographic properties is proposed by searching combinations based on gate-level circuits using a depth-first strategy. It exhibits better security properties and hardware performance compared to other S-boxes. The block cipher GFLE is implemented in ASIC with UMC 0.18 μm. It has been proved that the energy of GFLE is lower than Midori, WARP, SKINNY, CRAFT, etc in unified encryption and decryption (ED) circuits. GFLE reduces energy by 61.59% compared with SKINNY. The results show that GFLE in ED circuits consumes only 1596 Gate Equivalents (GEs) and 6.36 μ J/bit in area and energy, respectively.

Encrypted Traffic Decryption Tools: Comparative Performance Analysis and Improvement Guidelines

With the exponential growth of encrypted communication over the internet, research into systems capable of analyzing large volumes of encrypted traffic is essential. This study focuses on evaluating the performance of two prominent tools, ssldump and tshark, in decrypting and inspecting encrypted network traffic, assuming an environment where decryption keys are available. The performance of ssldump and tshark was assessed using various metrics, including execution time, and the ability to handle different file sizes and session counts. The results showed that tshark exhibited faster processing speeds for smaller file sizes and a higher number of sessions, while ssldump demonstrated better performance for larger file sizes and fewer sessions. However, notable performance differences were not observed based solely on the type of cipher suite or encryption method used. To enhance performance, the study proposes the session-based split and conquer (SSC) technique for automating parallelization using a multi-process approach. SSC shows up to a 39× improvement in performance, depending on system capabilities and workload.

SUMER: A New Family of Lightweight and Traditional Block Ciphers with Multi-Modes

With the recent increase in the risks and attacks facing our daily lives and digital environment around us,the trend towards securing data has become inevitable. Block ciphers play a crucial role in modern crypto-applicationssuch as secure network storage and signatures and are used to safeguard sensitive information. The present paperdevelops a new variant of the symmetric model called SUMER family ciphers with three equivalent modes: lightweight,conventional (traditional), and extended ciphers. SUMER name belongs to one of the oldest civilizations inMesopotamia and stands for Secure Universal Model of Encryption Robust Cipher. The SUMER cipher is based on asimple and robust symmetric structure and involves solid algebraic theories that completely depend on the Galois FieldGF(28). SUMER cipher is designed to work with two involutional structures of the Substitution-Permutation Network(SPN) and Feistel structure. These two involutional structures mean that the same algorithm is used for the encryptionand decryption process, and only the algorithm of the ciphering key is used in reverse order in both structures. TheSUMER lightweight structure is an elegant mode that does not need building an S-Box that requires a large amount ofmemory and a number of electronic logical gates as S-Box construction has been canceled and replaced by the on-flycomputation clue, which does not need a reserved memory for building S-Box. SUMER family ciphers also can work ina traditional mode or as an extended mode with high margin security. This family of ciphers is applicable with multimodes of various utilizations. The proposed ciphers are designed to be byte-oriented, showing good evaluation andresults under several measurement tests for speed, time implementation, and efficiency.

Decentralized Multi-Client Functional Encryption with Strong Security

Decentralized Multi-Client Functional Encryption (DMCFE) extends the basic functional encryption to multiple clients that do not trust each other. They can independently encrypt the multiple plaintext-inputs to be given for evaluation to the function embedded in the functional decryption key, defined by multiple parameter-inputs. And they keep control on these functions as they all have to contribute to the generation of the functional decryption keys. Tags can be used in the ciphertexts and the keys to specify which inputs can be combined together. As any encryption scheme, DMCFE provides privacy of the plaintexts. But the functions associated to the functional decryption keys might be sensitive too (e.g. a model in machine learning). The function-hiding property has thus been introduced to additionally protect the function evaluated during the decryption process. In this paper, we provide new proof techniques to analyze a new concrete construction of function-hiding DMCFE for inner products, with strong security guarantees: the adversary can adaptively query multiple challenge ciphertexts and multiple challenge keys, with unbounded repetitions of the same tags in the ciphertext-queries and a fixed polynomially-large number of repetitions of the same tags in the key-queries. Previous constructions were proven secure in the selective setting only.

Auditable and dynamic access control scheme with behavior and identity tracing

Ciphertext policy attribute-based encryption (CP-ABE) is a potential solution to security sharing issues since it offers one-to-many encryption and fine-grained access control. To prevent users from disclosing their access permissions, traceable CP-ABE schemes are emerging. However, the current traceable CP-ABE schemes still have some security problems, such as impromptu attribute retracting, unreliable tracking, and easy disclosure of access policy privacy, making it essential to implement dynamic data security sharing and malicious user auditing. To address these issues, we propose an auditable and dynamic access control scheme with behavior and identity tracing. The scheme first uses an access tree with hidden leaf nodes to express the access policy, improving the flexibility and security of access control. Secondly, the Blockchain and InterPlanetary File System (IPFS) frameworks perform the audit authentication and store the ciphertext, policy, and public keys to avoid tampering with shared data. Furthermore, to prevent users from leaking their decryption keys, a tracing algorithm based on white-box traceability is developed. On this basis, an authority update algorithm is proposed to revoke the malicious user’s permission immediately and update the decrypted key for unrevoked users. An auditable smart contract based on blockchain is proposed to prevent user denial. Finally, theoretical analyses prove that the proposed scheme not only achieves traceability, revocation, authority updating, policy hiding, and audit, but also guarantees security under a chosen plaintext attack model. Experiments demonstrate that our proposal reduces the key generation time by 22.6%, the encryption and decryption time by 39.2% and 59.8%, and the storage costs of ciphertext and private key are reduced by 12.1% and 5.6% over existing schemes.

From Offer to Breach: The Empirical Study on Quid Pro Quo Cyber Attack

Quid pro quo attacks are a sophisticated form of insider threat where malicious individuals exploit the human element within an organization to gain sensitive information or unauthorized access. Unlike traditional cyberattacks that focus on technical system flaws, these attacks rely on social engineering techniques to deceive people. Attackers often use ransomware, encrypting a victim's data and demanding payment, typically in cryptocurrency, for the decryption key. The term "quid pro quo" highlights the exchange involved, indicating that the attacker seeks something in return for stopping their harmful actions. To effectively understand and defend against quid pro quo attacks, a comprehensive approach is necessary. The primary goal of this research is to examine how these attacks operate and to propose effective solutions and preventive measures. This will be achieved by studying incidents involving affected victims. The research aims to identify the specific methods used in these attacks, analyze the vulnerabilities that allow them to succeed, and offer practical recommendations for improving cybersecurity defenses. By learning from the experiences of past victims, this research seeks to provide valuable insights that can be used to develop proactive strategies and security protocols to prevent or mitigate the impact of quid pro quo attacks in the future.

A method to mitigate cyber exploits on automatic dependent surveillance-broadcast (ADS-B) data transmissions

PurposeAutomatic dependent surveillance-broadcast (ADS-B) is the foundational technology of the next generation air transportation system defined by Federal Aviation Authority and is one of the most precise ways for tracking aircraft position. ADS-B is intended to provide greater situational awareness to the pilots by displaying the traffic information like aircraft ID, altitude, speed and other critical parameters on the Cockpit Display of Traffic Information displays in the cockpit. Unfortunately, due to the initial proposed nature of ADS-B protocol, it is neither encrypted nor has any other innate security mechanisms, which makes it an easy target for malicious attacks. The system is vulnerable to various active and passive attacks like message ingestion, message deletion, eavesdropping, jamming, etc., which has become an area of concern for the aviation industry. The purpose of this study is to propose a method based on modified advanced encryption standard (AES) algorithm to secure the ADS=B messages and increase the integrity of ADS-B data transmissions.Design/methodology/approachThough there are various cryptographic and non-cryptographic methods proposed to secure ADS-B data transmissions, it is evident that most of these systems have limitations in terms of cost, implementation or feasibility. The new proposed method implements AES encryption techniques on the ADS-B data on the sender side and correlated decryption mechanism at the receiver end. The system is designed based on the flight schedule data available from any flight planning systems and implementing the AES algorithm on the ADS-B data from each aircraft in the flight schedule.FindingsThe suitable hardware was developed using Raspberry pi, ESP32 and Ra-02. Several runs were done to verify the original message, transmitted data and received data. During transmission, encryption algorithm was being developed, which has got very high secured transmission, and during the reception, the data was secured. Field test was conducted to validate the transmission and quality. Several trials were done to validate the transmission process. The authors have successfully shown that the ADS-B data can be encrypted using AES algorithm. The authors are successful in transmitting and receiving the ADS-B data packet using the discussed hardware and software methodology. One major advantage of using the proposed solution is that the information received is encrypted, and the receiver ADS-B system can decrypt the messages on the receiving end. This clearly proves that when the data is received by an unknown receiver, the messages cannot be decrypted, as the receiver is not capable of decrypting the AES-authenticated messages transmitted by the authenticated source. Also, AES encryption is highly unlikely to be decrypted if the encryption key and the associated decryption key are not known.Research limitations/implicationsImplementation of the developed solution in actual onboard avionics systems is not within the scope of this research. Hence, assessing in the real-time distances is not covered.Social implicationsThe authors propose to extend this as a software solution to the onboard avionics systems by considering the required architectural changes. This solution can also bring in positive results for unmanned air vehicles in addition to the commercial aircrafts. Enhancement of security to the key operational and navigation data elements is going to be invaluable for future air traffic management and saving lives of people.Originality/valueThe proposed solution has been practically implemented by developing the hardware and software as part of this research. This has been clearly brought out in the paper. The implementation has been tested using the actual ADS-B data/messages received from using the ADS-B receiver. The solution works perfectly, and this brings immense value to the aircraft-to-aircraft and aircraft-to-ground communications, specifically while using ADS-B data for communicating the position information. With the proposed architecture and minor software updates to the onboard avionics, this solution can enhance safety of flights.

BFL-SA: Blockchain-based federated learning via enhanced secure aggregation

Federated learning, involving a central server and multiple clients, aims to keep data local but raises privacy concerns like data exposure and participation privacy. Secure aggregation, especially with pairwise masking, preserves privacy without accuracy loss. Yet, issues persist like security against malicious models, central server fault tolerance, and trust in decryption keys. Resolving these challenges is vital for advancing secure federated learning systems. In this paper, we present BFL-SA, a blockchain-based federated learning scheme via enhanced secure aggregation, which addresses key challenges by integrating blockchain consensus, publicly verifiable secret sharing, and an overdue gradients aggregation module. These enhancements significantly boost security and fault tolerance while improving the efficiency of data utilization in the secure aggregation process. After security analysis, we have demonstrated that BFL-SA achieves secure aggregation even in malicious models. Through experimental comparative analysis, BFL-SA exhibits rapid secure aggregation speed and achieves 100% model aggregation accuracy.

Enhancing the Secure Transmission of Data Over Optical Fiber Networks from Source to Destination

ABSTRACT The quantum key distribution (QKD) method allows for the safe creation of encryption keys between trusted entities for secure communication. The suggested system is designed to enable secure communication between multiple parties (a single sender, Alice, and multiple receivers, Bobs) connected via a public channel susceptible to interception. It enables Alice to privately share encryption keys with each Bob over dedicated quantum channels, which can then be used to decrypt messages sent over the public network. The procedure involves Alice generating optical signals with randomly assigned properties such as intensity, phase, polarization, and frequencies. Alice randomly sends either signal states carrying information or decoy states with different frequencies to the receivers (Bobs) over the quantum channels. She also sends a synchronization signal for timing alignment with the quantum signals over the optical links. At the receiving end, the synchronization pulse timestamps the incoming quantum signals. Each Bob then randomly alters the frequencies of the received quantum signals and randomly measures their phase or polarization. The key is created from the frequency, phase, or polarization information of the quantum signals, resulting in longer keys. Key management agents manage the securely QKD-generated keys to encrypt information before sending it to the intended receivers. Essentially, this framework establishes authenticated, private communication by using QKD over dedicated ultra-secure quantum links to distribute decryption keys, ensuring that only intended users can access the content. The approach is designed to ensure end-to-end secure communication across the network.

A Single-Sized Metasurface for Image Steganography and Multi-Key Information Encryption

With the escalating flow of information and digital communication, information security has become an increasingly important issue. Traditional cryptographic methods are being threatened by advancing progress in computing, while physical encryption methods are favored as a viable and compelling avenue. Metasurfaces, which are known for their extraordinary ability to manipulate optical parameters at the nanoscale, exhibit significant potential for the revolution of optical devices, making them a highly promising candidate for optical encryption applications. Here, a single-sized metasurface with four independent channels is proposed for conducting steganography and multi-key information encryption. More specifically, plaintext is transformed into a ciphertext image, which is encoded into a metasurface, while the decryption key is discretely integrated into another channel within the same metasurface. Two different keys for steganographic image unveiling are also encoded into the metasurface and can be retrieved with different channels and spatial positions. This distributed multi-key encryption approach can enhance security, while strategically distributing images across distinct spatial zones serves as an additional measure to reduce the risk of information leakage. This minimalist designed metasurface, with its advantages of high information density and robust security, holds promise across applications including portable encryption, high-camouflaged image display, and high-density optical storage.

An encrypted hiding scheme for 3D objects based on CGH and Henon mapping

A method is proposed to enhance the security of three-dimensional (3D) objects through computer-generated hologram (CGH) encryption and hiding. The process begins by encoding the 3D object using an iterative angular-spectrum layer-oriented method to create an optimized phase-only CGH. Next, the encrypted image is produced by modulating the phase-only CGH with a chaotic random phase mask (CRPM) generated through Henon mapping. Subsequently, a combination of discrete wavelet transform (DWT) and singular value decomposition (SVD) is utilized to embed the encrypted data into a visually secure image, ensuring the encryption and concealment of 3D objects. During decryption, the accurate decryption procedure and keys must be applied to achieve the final reconstruction. The utilization of CGH in conjunction with CRPM effectively enhances the security of 3D objects, while the integration of DWT and SVD ensures the visual security properties of the encrypted data, providing a dual layer of protection for 3D objects. Experimental simulation results demonstrate that this approach achieves high-security encryption and concealment of 3D objects, ensuring high-quality decryption of 3D objects during the reconstruction process.

Secure Data in the Cloud with a Robust Hybrid Cryptographic Approach

Cloud security combines hybrid symmetric encryption and key management to protect user privacy. Our approach can be easily scaled to meet growing cloud data security needs. Cloud computing's basic tenet is resource sharing, which is used for data storage, analysis, and management. Since many people use cloud services and are spread out across the internet, they present many security risks. Hybrid clouds, which can be accessed from anywhere, provide numerous advantages. The security solution (infrastructure as a service) is compatible with many PaaS, SaaS, and even IaaS cloud services. Furthermore, it is consistent with the vast majority of existing cloud solutions. Cloud computing security can be strengthened by using hybrid public key cryptosystems. Concerns about data security have made many businesses wary of cloud computing. The study aims to secure cloud computing by combining the Rabin and Rivest-Shamir-Adleman (RSA) cryptographic models. Analyzing how well a combination of methods generates secure encryption and decryption keys for data. The pure RSA system has longer response times and requires fewer computations compared to the hybrid system.

Chaotic Encryption Scheme for Colour Image using 3D Lorenz Chaotic Map and 3D Chen System

Chaos-based image encryption system is an encryption method that uses chaotic systems in encrypting digital images for the purpose of enhancing security. Chaos theory exhibits some distinctive characteristics, which include butterfly-like patterns, unpredictable behavior, and sensitive dependence to initial conditions. . In the past few decades, image encryption based on a single chaotic map has been a common technique in encrypting images. However, there are still unauthorized interceptors who illegally access and obtain the private information of the image. With that being the case, an encryption method that applies more than one chaotic system will contribute to creating a more complex relationship between the original and encrypted images, making it challenging for unauthorized individuals to decipher or extract the original content of the image without the appropriate decryption key. In this study, two chaotic maps, 3D Lorenz Map and 3D Chen system, are applied to generate random cryptographic keys for encrypting color images using permutation and diffusion mechanisms. The proposed algorithm that employs two chaotic maps is proven to be an effective system that achieves excellent results in security.

Enhancing Healthcare Data Security Using Quantum Cryptography for Efficient and Robust Encryption

Healthcare requires data encryption to safeguard sensitive patient information from unauthorized access or breaches. Encryption ensures that data is encoded into a secure format, making it unreadable to anyone without the decryption key. This helps maintain patient privacy, protects against identity theft, and ensures compliance with data protection regulations like HIPAA (Health Insurance Portability and Accountability Act.). With encryption, healthcare organizations can mitigate the risk of data breaches and uphold trust with patients by ensuring the confidentiality and integrity of their medical records and personal information. Quantum cryptography emerges as a revolutionary solution, offering unparalleled encryption for healthcare data. This process initiates with the meticulous crafting of quantum states to encapsulate healthcare data securely, ensuring precise encoding. Subsequently, quantum entanglement is established between sender and receiver, creating a secure communication channel resistant to interception attempts. Quantum key distribution then generates a secure key leveraging entangled quantum states, becoming the cornerstone of encryption. Quantum encryption shields healthcare data in an impenetrable veil of secrecy, leveraging the complexities of quantum mechanics to thwart unauthorized decryption attempts. The decryption process, facilitated by the shared secure key, unveils the encrypted healthcare data exclusively to authorized parties, preserving confidentiality with unparalleled precision. The result reveals quantum cryptography's superiority in healthcare data encryption. At 150-bit key length, quantum cryptography takes 352,237 milliseconds vs. AES's 310,285 milliseconds. For a 14 KB input, quantum cryptography requires 7 milliseconds compared to AES's 12 milliseconds. These metrics highlight quantum cryptography's efficiency gains and transformative potential in healthcare data security, promising both enhanced security and efficiency benefits.

Enhancing Healthcare Data Security Using Quantum Cryptography for Efficient and Robust Encryption

Healthcare requires data encryption to safeguard sensitive patient information from unauthorized access or breaches. Encryption ensures that data is encoded into a secure format, making it unreadable to anyone without the decryption key. This helps maintain patient privacy, protects against identity theft, and ensures compliance with data protection regulations like HIPAA (Health Insurance Portability and Accountability Act.). With encryption, healthcare organizations can mitigate the risk of data breaches and uphold trust with patients by ensuring the confidentiality and integrity of their medical records and personal information. Quantum cryptography emerges as a revolutionary solution, offering unparalleled encryption for healthcare data. This process initiates with the meticulous crafting of quantum states to encapsulate healthcare data securely, ensuring precise encoding. Subsequently, quantum entanglement is established between sender and receiver, creating a secure communication channel resistant to interception attempts. Quantum key distribution then generates a secure key leveraging entangled quantum states, becoming the cornerstone of encryption. Quantum encryption shields healthcare data in an impenetrable veil of secrecy, leveraging the complexities of quantum mechanics to thwart unauthorized decryption attempts. The decryption process, facilitated by the shared secure key, unveils the encrypted healthcare data exclusively to authorized parties, preserving confidentiality with unparalleled precision. The result reveals quantum cryptography's superiority in healthcare data encryption. At 150-bit key length, quantum cryptography takes 352,237 milliseconds vs. AES's 310,285 milliseconds. For a 14 KB input, quantum cryptography requires 7 milliseconds compared to AES's 12 milliseconds. These metrics highlight quantum cryptography's efficiency gains and transformative potential in healthcare data security, promising both enhanced security and efficiency benefits.

Unbounded non-zero inner product encryption

In a non-zero inner product encryption (NIPE) scheme, ciphertexts and keys are associated with vectors from an inner-product space. Decryption of a ciphertext for x→ is allowed by a key for y→ if and only if the inner product 〈x→,y→〉≠0. Existing constructions of NIPE assume the length of the vectors are fixed apriori. We present the first constructions of unbounded non-zero inner product encryption (UNIPE) with constant sized keys. Unbounded here refers to the size of vectors not being pre-fixed during setup. Both constructions, based on bilinear maps, are proven selectively secure under the decisional bilinear Diffie-Hellman (DBDH) assumption.Our constructions are obtained by transforming the unbounded inner product functional encryption (IPFE) schemes of Dufour-Sans and Pointcheval (ACNS 2019), one in the strict domain setting and the other in the permissive domain setting. Interestingly, in the latter case, we prove security from DBDH, a static assumption while the original IPFE scheme relied on an interactive parameterised assumption. In terms of efficiency, features of the IPFE constructions are retained after transformation to NIPE. Notably, the public key and decryption keys have constant size.