2.1. Overview Cryptography

Battery-scarce IoT devices are smart devices with many sensors that send data to a base station for use in a variety of applications such as home automation, healthcare, surveillance, and environmental monitoring. Their growing popularity is fueled by their energy efficiency and low power consumption. However, these devices are powered mostly by batteries, which eventually reduce and must be replaced, causing considerable maintenance issues. This is especially important for sensors installed in difficult-to-reach locations, such as medical implants, remote monitoring systems, and structural health monitoring of buildings and bridges. In order to get over this restriction, scientists have looked at alternate energy sources that increase the lifespan of devices and lower maintenance needs. However, in order to provide safe data transmission and storage without depleting these devices’ limited resources, lightweight encryption is essential.

Our primary focus will be on lightweight block ciphers, which are the foundation for many cryptographic algorithms.

2.2. Hash Function–Based Lightweight Algorithms

Cryptographic hash functions are cryptographic primitives that maintain data integrity and authentication. For secure communication to occur in a variety of networks and applications, data integrity and authenticity must be guaranteed. Requiring a lot of resources, current message authentication algorithms are not appropriate for systems with limited resources, such as real-time and IoT systems [10]. As a result, the following lightweight cryptographic hash function algorithms have been proposed by researchers.

Noura et al. [11] propose a lightweight keyed hash function scheme that reduces the total number of rounds to one, which is advantageous for resource-constrained systems [11]. The proposed solution attempts to achieve desired cryptographic properties, such as resistance against collision with low computation and complexity and message and key avalanche effects. Their security and performance analysis indicates that the recommended keyed hash function has low resource overhead and is immune to known security vulnerabilities. The following are some possible issues with the paper and recommendations for future development [11].

Security analysis: The paper should provide a more comprehensive security analysis of the proposed keyed hash function scheme. This could include a detailed discussion of potential vulnerabilities, threat models, and a comparison with existing secure hash functions to demonstrate the effectiveness of the proposed scheme.

Performance evaluation: While the paper briefly mentions performance analysis, a more in-depth evaluation of the computational performance, resource utilization, and comparison with existing hash function schemes would enhance the paper’s credibility.

Real-world implementation: It would be beneficial to include a section discussing the practical implementation aspects of the proposed scheme. This could involve considerations for integration into existing systems, interoperability, and potential challenges in real-world deployment.

Cryptanalysis and attacks: The paper could benefit from a discussion of potential cryptanalysis techniques and attacks that could be relevant to the proposed scheme. Addressing these potential weaknesses and providing countermeasures would strengthen the paper’s contribution.

Experimental validation: If applicable, the inclusion of experimental validation, such as implementation on real devices or simulation in a controlled environment, would provide empirical evidence of the scheme’s effectiveness and practicality.

Comparison with state of the art: A more detailed comparison with state-of-the-art lightweight cryptographic algorithms and hash function schemes would help situate the proposed scheme within the current research landscape.

Addressing these potential shortcomings in future work would enhance the credibility, applicability, and impact of the proposed keyed hash function scheme based on the RC4 stream cipher.

In Madushan et al. [12], the major contribution of the review lies in its comprehensive analysis of the NIST lightweight cryptography finalists and their fault analyses. The authors provide a detailed overview of the specifications, structures, design primitives, security parameters, advantages, and disadvantages of the finalists. Additionally, the specific focus on fault analyses, including the application of different fault attacks and the vulnerabilities of lightweight ciphers to such attacks, adds significant value to the cryptographic community’s understanding of the security implications for resource-constrained IoT devices. This review serves as a valuable resource for researchers, practitioners, and stakeholders involved in the development and deployment of lightweight cryptographic algorithms in IoT and other resource-constrained environments. However, the review identifies several open research problems that warrant further investigations. Specifically, the authors note the limited number of investigations of side-channel attacks on the NIST lightweight cryptography finalists and emphasize the need for future research to focus on analyzing these algorithms from the perspective of side-channel leakage and resistance against side-channel attacks. Additionally, the authors highlight the need to explore further fault models for specific ciphers, such as Elephant and Grain-128AEAD, as well as the importance of investigating quantum-safe lightweight cryptography for future standardization. These identified gaps in research present valuable opportunities for future studies to enhance the understanding of the security implications and resilience of lightweight cryptographic algorithms in resource-constrained environments.

2.3. Stream Cipher–Based Lightweight Algorithms

Noura et al. [13] suggested a stream cipher-based lightweight algorithm called LESCA stream cipher to provide a lightweight cryptographic solution with low computational complexity and minimal resource consumption. It is aimed at achieving a balance between security and performance, especially for power-constrained devices and real-time applications. The cipher utilizes dynamic key-dependent cryptographic primitives and a selective update process to enhance security without compromising efficiency. Additionally, it is aimed at achieving high throughput and error tolerance, making it suitable for noisy wireless channels. The main contribution of the LESCA stream cipher lies in its ability to provide a lightweight and efficient cryptographic solution for emerging systems, particularly in the context of IoT networks. By introducing dynamic cryptographic primitives, selective update processes, and flexible block lengths, LESCA attempts to balance security and performance. Its key contributions include enhancing security, reducing computational complexity, and improving error tolerance, all while maintaining high efficiency and flexibility. However, in the future, it would be important to conduct a thorough analysis of potential drawbacks or limitations of the LESCA stream cipher. Some areas of focus for this analysis could include resistance to advanced attacks, resource constraints, and standardization considerations. By conducting a comprehensive analysis of these potential drawbacks, researchers and practitioners can gain a deeper understanding of the practical implications and limitations of LESCA, leading to further refinement and improvement of the cipher for future applications.

According to [14], this survey has several popular stream ciphers that are recommended for securing data in IoT devices due to their efficiency, lightweight nature, and suitability for constrained environments. Here are some of the commonly recommended stream ciphers for securing data on IoT devices: The Fruit stream cipher has been highlighted in the survey for its good resistance to known attacks. It offers a balance between security and efficiency, making it a suitable choice for securing data in IoT devices [14]. Enocoro128 is another stream cipher known for its large throughput, which can be beneficial for IoT applications where data transmission speed is crucial. Its efficiency and performance make it a popular choice for securing data in constrained environments [14]. The F-FCSR stream cipher is recognized for its large throughput and efficiency, making it well-suited for resource-constrained devices like IoT sensors and smart devices. Its lightweight design and cryptographic capabilities make it a recommended choice for securing data in IoT ecosystems [15].

The WG stream cipher is known for its speed and efficiency, making it a suitable option for securing data in IoT devices with limited resources. Its fast encryption capabilities and lightweight nature make it a popular choice for applications where performance is critical. The Grain stream cipher is designed to be fast and efficient, making it a preferred choice for securing data in IoT devices. Its cryptographic strength and suitability for constrained environments make it a reliable option for ensuring data security in IoT ecosystems [15]. The MICKEY-128 stream cipher is recognized for its efficiency and cryptographic capabilities, making it a recommended choice for securing data in IoT devices. Its performance and suitability for resource-constrained environments make it a valuable cryptographic solution for IoT applications [15].

These stream ciphers offer a combination of security, efficiency, and performance, making them well-suited for securing data in IoT devices operating in constrained environments. By leveraging these popular stream ciphers, IoT devices can ensure the confidentiality and integrity of data exchanged within IoT networks while optimizing resource utilization and energy efficiency. However, according to [16], the survey “A Survey on Stream Ciphers for Constrained Environments” explores the use of stream ciphers to enhance the security of data in IoT devices operating in resource-constrained environments. It discusses the characteristics of lightweight stream ciphers, their advantages over block ciphers, and their suitability for IoT applications. The survey highlights popular stream ciphers such as Fruit, Enocoro128, F-FCSR, WG, Grain, and MICKEY-128, emphasizing their resistance to attacks, throughput, and efficiency for securing data in IoT devices. The paper suggests future research directions, including the development of new lightweight stream ciphers, security analysis, performance optimization, integration with IoT security protocols, real-world evaluations, and standardization efforts to advance the use of stream ciphers in securing IoT devices effectively.

According to [17], cloud services have revolutionized the storage and sharing of data, but they also pose security challenges. The analysis of popular cloud services like Wuala, DropBox, and Google Drive revealed their security methods and encryption algorithms. While AES provides high security but has vulnerabilities, RC4 offers speed but is prone to key-related issues. SHA1 is fast but lacks robust protection. An improved stream cipher based on RC4-128 was developed to enhance security without compromising performance. Continuous advancements in encryption algorithms are crucial for safeguarding data in cloud services. But, the study on the Improved Secure Stream Cipher for Cloud Computing includes a focus on a specific set of cloud services, potential oversight of all vulnerabilities in encryption algorithms, and a possibly restricted evaluation of the improved stream cipher. As future works for the study on the Improved Secure Stream Cipher for Cloud Computing involve exploring broader analyses of encryption algorithms, integrating advanced encryption techniques, investigating the impact of the improved stream cipher in various cloud computing environments, and staying updated on evolving cybersecurity challenges and encryption technologies [17].

2.4. Block Cipher Lightweight Algorithms

Sherine Jenny et al. [18] proposed the design of a compact S_box for resource-constrained applications. S-box, or substitution box, is an important component in many cryptographic algorithms. It is a mathematical function that maps a certain number of input bits to a certain number of output bits. S-boxes are used to add confusion and diffusion to the plaintext, making it more difficult for attackers to decipher the encrypted message. Robustness, balancing, differential uniformity, nonlinearity, linear approximation, algebraic complexity, fixed and opposite fixed points, and the bit avalanche criterion are among the attributes that make an S-box strong. The design of a compact S-box is specifically tailored for resource-constrained applications, such as those found in IoT devices. As such, the compact S-box is designed to be smaller in size and consume less power than a regular S-box. The compact S-box proposed in this article is [18] designed using a combination of Boolean functions and Galois field arithmetic, which reduces the number of gates required for implementation and improves its efficiency. While the compact S-box proposed in this article is specifically designed for use in lightweight block ciphers for resource-constrained applications, it is possible that it could be used in other applications as well. However, further research would be needed to determine its suitability for other applications [19].

Thakor et al. [8] proposed lightweight cryptographic algorithms for resource-constrained IoT devices. In this study, none of the LWC algorithms fulfill all the criteria of hardware and software performance metrics, but they perform at their best in the specified environment. However, new attacks are reported with the growth of new LWC algorithms, which shows an inevitable and never-ending research process. The war between cybersecurity experts and attackers always opens a door of opportunities for new research in the field of cybersecurity, especially lightweight cryptography.

Hossain et al. [20] proposed the design and development of a novel symmetric algorithm for enhancing data security in cloud computing to secure and enhance the protection of data stored in the cloud. A hash value is also generated for authentication. The algorithm developed by the authors ensures data confidentiality, integrity, and authenticity for data stored in the cloud. But it works on text format data only, and key and hash code exchange is less secure and efficient.

Thabit et al. [21] proposed a new lightweight cryptographic algorithm (NLCA) for enhancing data security in cloud computing. A NLCA is proposed to improve cloud computing protection with low processing overhead and high performance. It is intended to improve data security in cloud computing environments. The primary goal of the NLCA is to encrypt data using a 16-byte (128-bit) block cipher and a 16-byte (128-bit) key. A symmetric-key algorithm is needed for the encryption process, and each encryption round always depends on mathematical functions to produce confusion and diffusion. Because of its quick data collection and processing times, it is even more useful in the field of cloud computing. However, the suggested work is comparable to AES’s current output. It is intended to be used with a 16-byte (128-bit) block cipher.

Usman et al. [22] reviewed on lightweight encryption for the low-powered IoT devices. Since the large key sizes in the asymmetric algorithms are unsuitable for the IoT, the lightweight encryption algorithms typically use symmetric key algorithms. The encryption and decryption processes are complementary to one another when employing Feistel networks in symmetric key algorithms. This lowers latency, preserves memory and circuitry in the limited device, and reduces code size. The development of lightweight encryption algorithms is essential because the IoT’s resource-constrained devices cannot use the most advanced encryption algorithms. On the other hand, the algorithm that was developed performed insignificantly.

Sawant et al. [23] discussed the “PRESENT block cipher algorithm” and its suggested design and execution. Lightweight and simple to implement in both hardware and software, the “PRESENT block cipher algorithm” uses substitution and permutation blocks of only 4 bits. Sixty-four bits are used for blocks, and either 80 or 128 bits are used for keys. For the present block cipher, there are a total of 31 rounds. When this algorithm is implemented, an encryption module specifically for FPGA data transmission is created, improving security. This guarantees that unauthorized parties cannot access the data and that it is protected during transmission. Furthermore, the algorithm can be implemented on some of the smallest FPGAs available on the market due to its lightweight nature. Because of its ability to balance security, effectiveness, and adaptability, the “PRESENT block cipher algorithm” is a good choice for a wide range of everyday encryption and decryption applications, from secure communication in contemporary digital ecosystems to the protection of personal data. On the other hand, comparing the algorithm’s performance to other lightweight encryption algorithms may be a research gap that needs to be filled in the future. Future studies could therefore concentrate on assessing the algorithm’s efficiency, security, and speed, as well as contrasting it with other lightweight encryption algorithms to identify its advantages and disadvantages. Furthermore, additional research could examine the algorithm’s possible weaknesses and look into ways to strengthen its defenses against possible intrusions.

In June 2013, the National Security Agency (NSA) released the Speck family of portable block ciphers to the general public. Speck has been optimized for performance in software implementations, while Simon, Speck’s sister algorithm, has been optimized for hardware implementations. Speck is an add-rotate-xor (ARX) cipher [13]. Unlike other lightweight block ciphers currently in use, Simon and Speck support a wide range of block and key sizes, which allows the cryptography to be precisely tailored to a given application. Thanks to the approach we took to their design, we are confident that Simon and Speck will continue to deliver exceptional performance on tomorrow’s IoT devices [13].

In Seddiq et al. [24], its lightweight design ensures quicker encryption and decryption times with less computational overhead. The algorithm improves security robustness against possible attacks by combining the Feistel network and substitution–permutation network (SPN) structures, in addition to multiple rounds and key addition layers. The ability to select 10, 16, or 20 rounds freely allows for adaptability to various security needs. The algorithm’s efficacy in delivering secure encryption is confirmed by evaluation metrics like implementation time tests, avalanche effect tests, and randomness tests. Because of its adaptability, it can be used in a variety of sectors where resource constraints necessitate secure data encryption. Overall, the algorithm is an effective encryption solution for protecting sensitive data while preserving peak performance because of its careful consideration of both speed and security. The article’s suggested hybrid lightweight cipher algorithm is made to offer safe data encryption in settings with limited resources. It benefits a range of industries and applications, such as the following [25]:

IoT: This technology can be used to secure IoT devices that have limited resources by providing safe data transfer and communication. Mobile and wireless communication: This provides quick and effective encryption to improve data security in mobile devices and wireless networks. Healthcare: By safeguarding private patient data during transmission and storage, this sector enhances data security. Financial services: These provide confidentiality and integrity for financial transactions and customer data in financial institutions. Smart grids: These improve communication security in energy management by offering a secure encryption solution for smart grid systems. Industrial control systems: These strengthen cybersecurity in sectors that depend on control systems to safeguard vital data and infrastructure. Government and defense: By offering security features to safeguard classified information, this helps government organizations and the defense industry. Cloud computing: This provides safe data transmission and storage with confidentiality and integrity, improving data security in cloud environments. All things considered, the hybrid lightweight cipher algorithm finds extensive use in many sectors where effective encryption and data security are critical, particularly in settings with constrained computational capacity. However, the limited scope of testing and real-world implementation on the hybrid lightweight cipher algorithm may need to be addressed in future research. The algorithm’s performance and security robustness in real-world, diverse environments need to be further validated through extensive testing and deployment, even though simulations and theoretical analysis show promise. Future research should concentrate on carrying out extensive real-world testing, benchmarking against current ciphers, thorough security analysis, scalability assessment, and alignment with industry standards and cryptography guidelines in order to improve the algorithm’s credibility and applicability. By taking care of these issues, the algorithm’s practical implementation across a range of industries and applications can be validated and optimized, guaranteeing its security and dependability in real-world situations [25].

2.5. Lightweight S-Box Design Algorithms

In Aboytes-González et al. [26], the enhanced security of S-boxes resulting from the proposed method in the study can have several potential applications in real-world scenarios: improved cryptosystems, secure communication, network security, IoT security, blockchain technology, and data privacy. Generally, the application of enhanced S-box security can have a broad impact on various sectors where data security and privacy are critical, ultimately contributing to a more secure digital environment. But the paper does not extensively discuss the potential trade-offs or drawbacks of implementing the proposed method in practical cryptographic systems. It is essential to consider factors such as computational overhead, implementation complexity, and compatibility with existing cryptographic protocols when introducing new methods for enhancing S-box security.

According to [27], implementing traditional cryptography algorithms on resource-constrained IoT devices faces challenges such as limited memory, low processing power, small physical area, energy consumption, complexity, security risks, compatibility issues, and scalability concerns. Adapting these algorithms for IoT devices requires optimization, simplification, and customization to ensure efficient and secure operation within the device constraints. The novel 5-bit S-box design proposed in the article addresses the limitations of lightweight cryptography by offering resource efficiency, flexibility for various block sizes, enhanced security through a chaotic mapping technique, a comparative advantage over existing S-box designs, and an overall balanced solution to meet the requirements of resource-constrained IoT devices [27].

The research on the novel 5-bit S-box design for lightweight cryptography algorithms can enhance security for IoT devices in various industries such as IoT security, smart homes, healthcare, industrial IoT, transportation, logistics, retail, supply chain, and financial services. The applications include securing communication, protecting sensitive data, preventing cyber threats, ensuring privacy, and safeguarding critical infrastructure across different sectors. However, one limitation of the paper on the novel 5-bit S-box design for lightweight cryptography algorithms is the absence of real-world implementation and testing on a diverse range of IoT devices. Future research should focus on conducting real-world testing, scalability assessment, energy efficiency analysis, interoperability testing, robustness evaluation, performance benchmarking, and user feedback validation to enhance the credibility and applicability of the proposed 5-bit S-box design for IoT devices [27].

According to [28], the paper “Design of a Lightweight Cryptographic Scheme for Resource-Constrained Internet of Things Devices” introduces the Small lightweight cryptographic algorithm (SLA) specifically designed for IoT devices. SLA is structured as a SPN with 16 rounds and supports key lengths of 80/128 bits. It incorporates nonlinear S-box and linear permutation layers to ensure security and efficiency. The S-box in SLA enhances the complexity of the cipher design by introducing nonlinearity, which helps in thwarting attacks and improving robustness. However, “Design of a Lightweight Cryptographic Scheme for Resource-Constrained Internet of Things Devices” lacks detailed analysis or discussion on the potential vulnerabilities or weaknesses of the SLA. While the paper highlights the security features and resistance to certain attacks, a more in-depth exploration of possible weaknesses, such as side-channel attacks or implementation vulnerabilities, could provide a more comprehensive understanding of the algorithm’s limitations. Additionally, the paper could benefit from discussing real-world implementation challenges or performance issues that may arise when deploying the SLA in practical IoT scenarios. Addressing these limitations would enhance the overall robustness and applicability of the proposed cryptographic scheme [28].

According to [29], the proposed S-box algorithm plays a crucial role in enhancing data encryption for network security in several ways: resistance to cryptanalysis, well-designed S-boxes are resistant to various cryptographic attacks such as linear and differential cryptanalysis. They are selected based on specific requirements to ensure that products can withstand rigorous scrutiny. Strengthening the key, S-boxes are integral in symmetric key ciphers for key mixing and expansion. They ensure that the secret key is applied in a complex and uncertain manner, enhancing the overall encryption process. Enhanced security layers, in ciphers like the AES, S-boxes contribute to multiple layers of security. The unique transformations of each S-box in AES make it robust against various attacks, adding to the overall security of the encryption. Confidentiality, S-boxes introduce nonlinearity into encryption processes, making it challenging for hackers to deduce the relationship between cipher text and plaintext without knowledge of the secret key. This feature helps maintain the confidentiality of sensitive data. Diffusion and avalanche effect, S-boxes play a role in diffusion and avalanche effects in cryptographic products. A small change in the key or plaintext results in a significant change in the cipher text output, making decryption more challenging for adversaries [29]. Generally, the S-box algorithm is a critical component in data encryption for network security, providing essential cryptographic strength and resilience needed to protect data during storage and transmission in the face of evolving cyber threats. As future research directions, the authors suggest potential future research directions, such as optimizing computational performance, exploring resilience to quantum attacks, and integrating the novel S-box algorithm into existing cryptographic systems. These recommendations pave the way for further advancements in network security and encryption technologies [29].

2.6. Lightweight Key Generation Algorithms

Sittampalam et al. [30] proposed enhanced symmetric cryptography for IoT using a novel random secret key (RSK) approach. This paper proposes a novel RSK technique to enhance the security of symmetric LWC algorithms for IoT applications. The experimental results show that the RSK is more resistant to key-based attacks, uses fewer resources, and provides more effective protection for symmetric LWC algorithms in all IoT systems. Nevertheless, this work only addresses key generation, not the more power-intensive step of symmetric cryptography algorithms.

Sohel Rana et al. [31] proposed a novel neural network (NN)–based key scheduling method for lightweight block ciphers. A multilayer feed-forward NN with a single hidden layer and a nonlinear activation function that satisfies the Shannon confusion properties is the foundation of the suggested NN technique. This is an illustration of the ideal NN for the key scheduling process, consisting of four input, four hidden, and four output neurons. This architecture generates five unique keys from 64-bit input data. Sufficient diffusion is achieved by using nonlinear bit shuffling. With less power and memory usage, the 4-4-4 NN technique ensures that secure keys are generated with an avalanche effect of greater than 50%. Nevertheless, this algorithm’s speed and performance fall short of what is needed for battery-scarred IoT devices.

2.7. Comparison of the Existing Algorithm

In this section, we provide a comparative analysis of selected lightweight cryptographic algorithms, emphasizing their structural and cryptographic characteristics.

The comparison is based on recent research contributions, with a focus on S-box size, algebraic degree, linear proximity, author information, and publishing source, along with the major insights from the literature summarized in Table 1.

This analysis aids in determining the strengths and limitations of existing techniques, as well as potential areas for development in lightweight cipher design for IoT devices with limited battery life.

According to Table 2, prior studies have focused on various aspects of lightweight cryptographic algorithms, including their implementation on constrained devices and specific improvements in security or efficiency. Several studies have focused on the applicability of lightweight cryptography in the IoT space. For example, Li et al. provided an overview of lightweight encryption algorithms specifically designed for low-power IoT systems [27, 36]. Their work, however, did not address recent innovations in hybrid encryption or hardware-software co-optimizations. Other researchers, such as Gupta et al., conducted a comprehensive review of lightweight block ciphers, focusing on optimization techniques such as reduced S-box complexity and optimized round functions [38]. While this work offered valuable insights into block ciphers, it lacked an evaluation of lightweight stream ciphers and energy-efficient public key algorithms, and Table 3 provides a summary of the literature review on lightweight cryptographic techniques.

2.8. Popular Lightweight Block Cipher Algorithms

Explain the fundamentals of lightweight cryptographic encryption algorithms. For example, the article discusses why traditional encryption methods (such as AES) are unsuitable for constrained devices and highlights key lightweight encryption standards such as PRESENT, SIMON, SPECK, KATAN, KTANTAN, AES, DESL, RECTANGLE, CLEFIA, HIGHT, CAMELIA, TEA, and TWINE.

The PRESENT lightweight cipher is an SPN network block cipher with a 64-bit block size and 80- or 128-bit keys. The PRESENT lightweight cipher is well-known for its simplicity and compatibility with hardware implementations [5].

SIMON and SPECK: The NSA developed SIMON optimized for hardware and SPECK optimized for software, both of which are lightweight block ciphers with block and key sizes ranging from 32 to 128 bits. They are highly adaptable and efficient across multiple platforms [35, 49, 50].

KATAN is designed for minimal hardware implementation, with a 32-bit block size and 80-bit key sizes. KTANTAN is a simplified version with a hardcoded fixed key [51, 52].

AES variants: Although the standard AES is computationally expensive, lightweight variants of AES are often used in constrained environments. Optimizations include reducing the number of rounds or simplifying key schedules [51, 52]. Table 4 shows the performance of popular lightweight block cipher algorithms.

3.1. Research Approach and Techniques Used

Describe the review procedure in depth. Data extraction techniques, inclusion/exclusion criteria, search strategy, and analysis tools are all included in this. The evaluation procedure was carried out methodically to guarantee the reliability and thoroughness of the results. The procedure included a number of crucial steps.

3.2. Search Strategy

This section explains how and where the relevant literature was searched. This typically includes academic databases such as IEEE Xplore, Springer Link, MDPI Digital Library, and Google Scholar. The search terms should focus on security, cryptography, lightweight cryptography, algorithms, energy efficiency, performance evaluation, etc.

3.3. Inclusion and Exclusion Criteria

Studies were chosen using precise inclusion and exclusion criteria to guarantee quality and relevance.

3.4. Quality Assessment

This outlines how the quality of selected papers is assessed. Factors include relevance to RQs, contribution to the field, study design and methodology, and impact factor of the journal or conference.

3.5. Key Challenges

This identifies the challenges encountered by lightweight cryptography [52]:

Energy efficiency: reducing power consumption while encrypting and decrypting

Processing power: achieving low latency while minimizing computational overhead

Memory consumption: reducing the size of encryption algorithms to fit into limited storage space

3.6. RQs

The main RQs guiding this review are as follows:

RQ1: What are the improved methods of lightweight cryptographic encryption algorithms presented in the literature?

RQ2: How do these improvements affect performance in battery-limited IoT devices?

RQ3: What evaluation metrics are used to assess the performance of battery-limited IoT devices?

4.1. Block Cipher Enhancements

This reviews the literature on recent block ciphers designed for lightweight applications and discusses improvements such as the following:

Reduced S-box complexity: simplifying the S-box to reduce computation

Efficient key scheduling: optimizing key schedule algorithms for speed and low memory usage

Round function optimization: enhancing round functions to balance security and performance

Several papers proposed improvements to existing block ciphers like PRESENT, CLEFIA, and SIMON. These improvements concentrated on optimizing the S-box, round function, and key scheduling to reduce computational complexity and power consumption. For example, Xie et al. introduced an optimized version of the PRESENT cipher that achieved a 30% reduction in power consumption while maintaining security [44, 55].

4.2. Stream Ciphers for Lightweight Encryption

This investigates improvements in stream ciphers, with a focus on their suitability in resource-constrained environments. Examples include the Grain and Trivium families. In the field of stream ciphers, lightweight algorithms like Grain and Trivium have been improved by reducing state size and round count [60]. Martinez et al. proposed a hybrid approach that combines stream ciphers with block cipher-like properties, resulting in a balance of speed and security [60].

4.3. Lightweight Public Key Cryptography

Recent research has focused on lightweight public key algorithms, particularly elliptic curve cryptography (ECC), to address the resource constraints of IoT devices. Efficient curve selections and optimized implementations have made ECC viable for IoT applications, with several studies reporting significant improvements in execution time and memory footprint. Additionally, research has analyzed enhancements in lightweight ECC and RSA specifically designed for IoT. This includes novel techniques for faster key generation, encryption, and decryption in constrained environments [30, 61, 62].

4.4. Energy-Efficient Cryptography

This is aimed at reducing the energy consumption of cryptographic operations, such as hardware accelerations, utilizing cryptographic hardware modules to speed up operations and optimize software implementations, fine-tuning software algorithms for minimal power usage [52, 63].

Significance of energy-efficient cryptography is as follows.

IoT devices: IoT devices, such as smart thermostats, security cameras, and wearable health monitors, require energy-efficient cryptographic solutions to secure data without depleting their limited battery resources [63–66].

Wireless sensor networks (WSNs): WSNs consist of specially distributed sensors that monitor physical or environmental conditions. These networks require secure, energy-efficient cryptographic protocols to ensure data confidentiality, integrity, and authenticity over long periods, often in remote locations [63–66].

Mobile devices and wearables: Devices like smartphones and fitness trackers need energy-efficient cryptography to secure sensitive user data without quickly draining the battery [63–69].

RFID tags and smart cards: These devices typically operate with minimal power and need lightweight, energy-efficient cryptographic algorithms to provide secure authentication and data protection in environments like contactless payment systems [63–66].

Automotive and industrial IoT: Energy-efficient cryptography is essential for secure communications between connected cars or in industrial IoT systems, where embedded devices monitor and control machinery with limited power availability.

Challenges and future directions are as follows [63–66, 70].

Balancing security and efficiency: As cryptographic algorithms become lighter and more energy-efficient, ensuring they remain secure against emerging threats (including quantum attacks) is a challenge. There is a constant trade-off between minimizing energy consumption and maintaining strong cryptographic guarantees.

Postquantum cryptography: The development of energy-efficient cryptographic algorithms that are also resistant to quantum computing attacks is an area of ongoing research. Quantum-safe cryptosystems, like lattice-based cryptography, must be optimized for low-power devices to maintain energy efficiency.

Adaptable cryptography: Dynamic cryptographic systems that can adapt based on available energy resources are being explored. These systems would adjust the level of security or type of algorithm used based on the current energy constraints of the device.

4.5. Hybrid Encryption Methods

This section discusses the combination of multiple lightweight techniques (e.g., combining stream and block ciphers) to achieve both flexibility and security. A new trend identified in the review is hybrid cryptographic methods combining lightweight block ciphers and stream ciphers. This approach has been shown to offer enhanced flexibility and security without sacrificing performance. Hybrid schemes, such as the one proposed by Zhao et al., can dynamically adjust encryption strategies based on the available resources [71].

4.6. Challenges and Research Opportunities

A significant challenge in lightweight cryptography is achieving maximum energy efficiency while maintaining security. Emerging research focuses on designing energy-efficient hardware and software implementations. The research opportunity is to investigate power consumption models and create hybrid techniques that incorporate energy-saving mechanisms while ensuring a high level of security.

4.7. Comparison of Lightweight Block Cipher Algorithms

The choice of lightweight block cipher depends on the specific use case and constraints of the IoT device. In Table 5, important characteristics of common lightweight block ciphers are compared.

Table 6 presents a comparison of lightweight block cipher algorithms, highlighting significant variations in memory, power, security, and resource use. Although AES has the strongest security (10.1), it is best suited for contexts where security is a top priority because it uses more memory (9.0), power (7.9), and resources (3.8). Strong security is also offered by DESL, KATAN, and KATYAN (9.2), with KATYAN being particularly resource-efficient (1.1). The memory and power consumption of SIMON, SPECK, and TEA are all minimal; SIMON has the least memory (4.0) and SPECK the lowest power (3.2), making them perfect for extremely limited IoT applications. Because they provide balanced performance, RECTANGLE, CLEFIA, and TWINE are flexible choices. The choice of cipher is determined by the particular application priorities, such as hardware simplicity, energy efficiency, or security.

Figure 1 compares 12 lightweight cryptographic algorithms on a scale of 1 (low) to 10 (high) based on four crucial factors: memory, power, security, and resource usage. Despite its minimal resource needs, AES performs well in terms of memory and power and receives the highest security grade. PRESENT, KATAN, and DESL are ideal for IoT devices with constrained resources due to their powerful memory and power efficiency. SPECK and SIMON offer good power performance but poor resource and security ratings. RECTANGLE and CLEFIA attain balance, but TWINE and TEA perform mediocrely overall. HEIGHT has the lowest ratings on the majority of metrics, making it unsuitable for applications that need to be secure or efficient.

Each cipher is designed for different priorities, balancing block size, key size, and efficiency, particularly for constrained environments like IoT devices. Lightweight block ciphers are designed to be suitable for resource-constrained devices such as IoT devices, RFID tags, and embedded systems. They prioritize efficiency in terms of memory footprint, power consumption, and computational cost while maintaining a reasonable level of security. This comparative analysis focuses on five prominent lightweight block ciphers: PRESENT, SIMON, SPECK, KATAN, and AES-128. The table provides key metrics: block size, key size, memory footprint, power efficiency, and security level.

Block size: The size of the data block that the cipher can encrypt or decrypt at once. A larger block size generally offers better security but also requires more computational resources. PRESENT: 64 bits, the smallest among the compared ciphers. SIMON, SPECK: variable block sizes from 32 to 128 bits, offering flexibility; KATAN: 32 bits, similar to PRESENT; and AES-128: 128 bits, the largest block size, providing the highest level of security.

Key size: The length of the secret key used for encryption and decryption. A longer key size generally increases security but also demands more computational power. PRESENT: 80 or 128 bits. SIMON, SPECK: 64–256 bits, offering a wide range of key lengths. KATAN: 80 bits and AES-128: 128 bits.

Memory footprint: The amount of memory required to implement the cipher. A smaller footprint is crucial for resource-constrained devices. PRESENT, KATAN: extremely low memory requirements, making them ideal for very small devices. SIMON, SPECK: low memory usage, suitable for most lightweight applications.

AES-128: Moderate memory consumption, compared to the others.

Power efficiency: The amount of power consumed during operation. Lower power consumption is essential for battery-powered devices. KATAN: very high power efficiency, making it suitable for energy-constrained environments; SIMON, SPECK, PRESENT: high power efficiency; AES-128: lower power efficiency compared to the other ciphers.

Security level: The resistance of the cipher to various attacks, such as brute-force attacks and cryptanalytic attacks. A higher security level is generally desired, but it often comes at the cost of increased computational resources.

SIMON, SPECK, AES-128: High-security level, considered to be resistant to known attacks. PRESENT, KATAN: Moderate security level, providing adequate protection for many applications but may be less suitable for high-security scenarios. The selection of a lightweight block cipher depends on the specific requirements of the application. For devices with extremely limited resources, PRESENT or KATAN might be the best choices due to their minimal memory footprint and power consumption. SIMON and SPECK offer a balance between security, efficiency, and flexibility. AES-128 provides the highest level of security but may be less suitable for resource-constrained environments. It is important to consider the trade-offs between security, efficiency, and memory footprint when choosing a lightweight block cipher. A thorough evaluation of the application’s needs will help determine the most appropriate option.

4.8. Analysis of Search Strategy

Similarly, the same formula is used to derive contributions from Springer Link (12.50%), MDPI (9.72%), Google Scholar (19.44%), and other sources (13.89%). Table 7 breakdown makes it evident which databases had the biggest impact on the literature study. With almost half of the reviewed publications coming from IEEE Xplore, it is clear that this source is the most important and relevant for research on lightweight cryptography. By demonstrating a diverse body of literature, this percentage analysis not only assesses the distribution of sources but also improves the study’s methodology’s legitimacy and transparency.

Figure 2 demonstrates that IEEE Xplore is the most used source of literature, accounting for 44.4% of the review, indicating a strong focus on peer-reviewed, domain-specific research; Google Scholar (19.4%) provided a broad aggregator to supplement database-specific searches; Springer Link (12.5%) and MDPI Digital Library (9.7%) provided access to recent and multidisciplinary studies; and the remaining 13.9% came from other sources, such as Science Direct, Wiley, and arXiv, guaranteeing a thorough and well-rounded review.

4.9. Performance Analysis

This section investigates improvements in lightweight cryptographic methods in terms of performance, security, and resource efficiency, responding to the RQs posed in the Introduction section. It evaluates how much the reviewed cryptographic algorithm enhancements improve performance in terms of speed, power consumption, and memory usage, providing insight into their overall effectiveness.

The reviewed improvements significantly enhanced performance metrics such as energy consumption, memory usage, and computational overhead. For instance, optimizing the S-box structure in block ciphers consistently reduced memory usage by up to 20%, while hardware accelerations in ECC led to a 40% reduction in execution time.

4.10. Security Analysis

This paper discusses how these improvements maintain or enhance the security of lightweight encryption methods. Assess whether the reduction in complexity leads to potential vulnerabilities. Although performance enhancements were evident, certain enhancements raised concerns regarding the security compromises. The reduction of the complexity of ciphers could potentially expose them to cryptanalysis attacks, despite the majority of studies demonstrating that their methodologies maintained adequate security margins.

4.11. Trade-Offs

The improvements in lightweight encryption often involve trade-offs between speed, security, and resource consumption. A common trend observed in the literature is that higher performance often comes at the expense of reduced cryptographic strength, particularly in lightweight block ciphers. This identifies the trade-offs between security, performance, and resource efficiency. For example, increased speed might reduce energy efficiency or weaken cryptographic strength.

6.1. Postquantum Lightweight Cryptography

Future research should concentrate on developing lightweight cryptographic algorithms that are resistant to quantum attacks while remaining efficient in terms of power and computational requirements, as the emergence of quantum computing poses a serious threat to established cryptographic protocols. The challenge is to develop energy-efficient postquantum algorithms that specifically address the constraints of resource-constrained IoT devices.

6.2. Automated Testing for Security and Efficiency

For lightweight cryptography methods to be effective in practical applications, automated evaluation is essential. Research might be focused on creating automated benchmarking tools that test, simulate, and assess how well cryptographic algorithms operate in different environments. In IoT situations, using AI and machine learning to dynamically modify cryptographic parameters might improve response to shifting security requirements.

6.3. Biologically Inspired Cryptographic Algorithms

Investigating bio-inspired algorithms could result in novel solutions that naturally maximize resource efficiency and robustness. Future studies could look into using evolutionary algorithms and swarm intelligence concepts to create adaptive cryptography models that can react to threats on their own while using the fewest resources possible.

6.4. Enhancing Algorithm Robustness Against Cryptanalysis

The simpler structures of lightweight cryptographic algorithms make them susceptible to cryptanalytic attacks. In order to increase their resistance without appreciably raising energy demands, research is necessary. This may entail creating sophisticated mathematical techniques and hybrid encryption algorithms that combine symmetric and asymmetric cryptography in order to increase security.

6.5. Energy-Efficient Design Principles

Energy-efficient solutions must be given priority in lightweight cryptography strategies due to the low battery life of IoT devices. In order to ensure sustainable operation in battery-limited conditions, future initiatives should focus on enhancing encryption algorithms to lower energy consumption while maintaining security integrity. Researchers can make substantial progress in lightweight cryptography by tackling these important areas, opening the door for safe and effective IoT applications that can handle the difficulties presented by contemporary technological environments.