Cipher Feedback Research Articles

Mobile-Based Learning Application for Enhancing Understanding of Cipher Feedback Algorithms

Mobile-Based Learning Application for Enhancing Understanding of Cipher Feedback Algorithms

Evaluations of Crypto-System AES Using Multiple Bloc Ciphering Mode

Cryptography, a scientific field that has existed even before the beginning of computer science. This article looks at the development symmetric crypto-system, which falls within the framework of image security, by Advanced Encryption Standard (AES- Advanced Encryption Standard) algorithms. AES algorithm is not integrity protected. Cryptanalysis could use modified encrypted image of each ciphered bloc for generating oracle and getting the key. A new crypto-system uses hash function named AES-GCM (Advanced Encryption Standard-) for solving this problem. Using Galois Counter Mode (GCM) combined with Secure Hash Algorithm 256 bits (SHA-256) or BLAKE2s hash function, the old mode of ciphering like: Cipher FeedBack (CFB), Output FeedBack (OFB), Cipher Block Chaining (CBC), Electronic Codebook Block (ECB) and CounTeR (CTR) mode encryption, will increase the security level at confidentiality and integrity. In this article, robustness of the crypto-system will be evaluated by multiple criteria, indeed the statistical analysis, sensitivity measurement and performance measurement. For the statistical analysis, the histogram is flat and the correlation between adjacent pixel is not linear for the encrypted image. The relation between clear image and encrypted image doesn’t exist. For the sensitivity analysis, Number of Pixel Changing Rate (NPCR) and Unified Averaged Changed Intensity (UACI) permit to avoid differential attack of the crypto-system. The two values are respectively near 99% and 30%. For performance measurement, the similarity of the decrypted image and original image will be tested. The Peak Signal to Noise Ratio (PSNR) and Mean Square Error (MSE) are equals of infinity and zero. The decrypted image and original image are the same. The integrity of the image on the crypto-system will be evaluated by modifying one bit of the encrypted image. The decryption process doesn’t give decrypted image and show that the tag value is incorrect.

A novel cancellable biometric recognition system based on Rubik’s cube technique for cyber-security applications

ObjectiveTen years ago, biometrics became an efficient tool of security and authentication enforcement. In a classical access system, a user can easily change password if it is compromised. However, user’s biometrics are limited and unique, and if a user biometric trait is compromised, it will be impossible to change it. Hence, cancellable biometric systems depend on the transformation of data or a biometric feature into a new format, so that users can replace their biometric templates in the same or a different system. In this paper, an efficient cancellable biometric recognition system is presented. In this system, both signal-and feature-level transformations are used to generate the cancellable templates MethodsA novel hybrid encryption framework based on the Rubik’s cube technique is presented to allow efficient encryption of face, iris, and fingerprint biometric templates. This framework begins with extraction of biometric features using the Scale-Invariant Feature Transform (SIFT). After that, the resulting biometric features are encrypted with the optical Double Random Phase Encoding (DRPE) algorithm. Then, the resulting encrypted biometric features are further encrypted with the chaotic Baker map permutation, Advanced Encryption Standard (AES), or Ron's Code (RC6) algorithm in the Cipher Feed Back (CFB) mode of operation. Finally, the resulting encrypted biometrics are additionally encrypted with the Rubik’s cube technique. The chaotic, RC6, or AES encrypted biometrics are utilized on the faces of the Rubik’s cube. From the concepts of image encryption, the DRPE, RC6, and the AES algorithms introduce a degree of diffusion, whilst the chaotic Baker map adds a degree of permutation. Moreover, the Rubik’s cube technique adds more permutation to the encrypted biometrics, simultaneously. The quality evaluation of the proposed cancellable biometric system reveals good performance. ResultsThe simulation results prove that the suggested hybrid encryption framework is reliable, and it presents recommended security and robustness levels for its utilization for building efficient cancellable biometric systems compared to the traditional techniques.

Proposed hybrid encryption framework for robust 3D image communication over wireless channels

ObjectiveDifferent cryptosystems have been presented to protect images, videos, and data against several types of attacks. These cryptosystems use small and medium keys with small and medium spaces, which limit the overall security. In this paper, a novel hybrid encryption framework depending on the Rubik’s cube technique is introduced to merge the results of different encryption algorithms. Methods: The suggested hybrid encryption framework begins with chaotic Baker map encryption with Cipher Feed-Back (CFB) mode which belongs to the permutation family, Advanced Encryption Standard (AES) and Ron's Code (RC6) in a first stage for encrypting multiple images, separately. Then, in the second stage, the resulting images are randomized again with Rubik’s cube technique. Chaotic, RC6 or AES encrypted images are utilized on the Rubik’s cube faces. The utilization of chaotic encryption, AES, RC6, and Rubik’s cube technique introduces encrypted images with both permutation and diffusion. The images after the encryption process are further transmitted through a wireless communication channel with different versions of Orthogonal Frequency Division Multiplexing (OFDM). Decryption is performed at the receiver side. The quality of the decrypted images at the receiver side reveals good encryption and decryption performance, especially when comparing with classical algorithms. ResultsThe simulation results show that the suggested hybrid encryption framework presents high security and robustness.

Novel design of cryptosystems for video/audio streaming via dynamic synchronized chaos-based random keys.

In this paper, a novel chaos-based cryptosystem is proposed to ensure the communication security of video/audio streaming in the network environment. Firstly, by the proposed synchronization controller for the master and slave chaotic systems, respectively, embedded in the transmitter and receiver, the cryptosystem can generate the synchronized and dynamic chaotic random numbers at the transmitter and receiver simultaneously. Then integrating the chaotic random numbers with SHA3-256 (Secure hash algorithm 3), the design of synchronized dynamic key generators (SDKGs) is completed. Continuously, we can apply the SDKGs to encrypt/decrypt streaming audio/video data. In our design, we introduce the AES CFB (Advanced encryption standard cipher feedback) encryption algorithm with SDKGs to encrypt the video/audio streaming. Then the cipher-text is transmitted to the receiver via the network public channel and it can be fully decrypted with the dynamic random keys synchronously generated at the receiver. A duplex audio/video cryptosystem is realized to illustrate the performance and feasibility of this proposed research. Finally, many tests and comparisons are performed to stress the quality of random sequences generated by proposed SDKGs.

A hybrid encryption framework based on Rubik’s cube for cancelable biometric cyber security applications

The need for high-speed and secure multi-biometric systems has grown in the last few decades. The progress in Internet applications and computer networks has prompted new problems with security and privacy. Having a reliable and secure means for storing biometrics is a necessary issue. Hence, data encryption and network security have become significant. Thence, because of the fast progress in network development, humans can easily and arbitrarily distribute or access digital data from networks. Therefore, ownership security has become a significant issue for individuals, and it requires much interest. Thus, there is a significant threat to copyright owners and digital multimedia producers to conserve multimedia from intruder prospection to avert loss in transmitted data. Ten years ago, most modern security systems depended on biometrics. Unfortunately, these systems have suffered for a long time from hacking trials. If the biometric databases have been hacked and stolen, the saved biometrics will be lost forever. Thus, there is a bad need to develop new cancelable biometric systems. In a classical authentication system, a user can easily change a password if it is compromised. However, the user’s biometrics are limited and unique, and if a user biometric is compromised, it will be impossible to change it in a particular system or at least difficult. Cancelable biometrics can be generated with intentional, repeatable distortions of biometric signals based on transforms. Hence, biometric templates are compared in the transform domain. Cancelable biometrics depend on transforming data to replace a single biometric template in the same or different systems. This paper presents a cancelable biometric system that depends on a novel hybrid encryption framework based on the Rubik’ cube technique. It allows simultaneous encryption of multiple images. The suggested hybrid enrollment stage begins with chaotic Baker map permutation in the Cipher FeedBack (CFB) operation mode, Advanced Encryption Standard (AES) or Ron's Code (RC6) algorithm as a first stage for encrypting the multiple images, separately. After that, the output encrypted images are passed to the second encryption stage via Rubik’s cube technique. Chaotic, RC6, or AES encrypted face images are utilized as the Rubik’s cube faces. For the RC6 and AES algorithms, they add a degree of diffusion, while the chaotic algorithm adds a degree of permutation. Moreover, the Rubik’s cube technique adds more permutations to the encrypted images, simultaneously. The encrypted images are used in the cancelable biometric system. The simulation results prove that the hybrid proposed encryption framework is efficient. Moreover, it has strong robustness and security.

Designing a Block Cipher in Galois Extension Fields for IoT Security

This paper focuses on a block cipher adaptation of the Galois Extension Fields (GEF) combination technique for PRNGs and targets application in the Internet of Things (IoT) space, an area where the combination technique was concluded as a quality stream cipher. Electronic Codebook (ECB) and Cipher Feedback (CFB) variations of the cryptographic algorithm are discussed. Both modes offer computationally efficient, scalable cryptographic algorithms for use over a simple combination technique like XOR. The cryptographic algorithm relies on the use of quality PRNGs, but adds an additional layer of security while preserving maximal entropy and near-uniform distributions. The use of matrices with entries drawn from a Galois field extends this technique to block size chunks of plaintext, increasing diffusion, while only requiring linear operations that are quick to perform. The process of calculating the inverse differs only in using the modular inverse of the determinant, but this can be expedited by a look-up table. We validate this GEF block cipher with the NIST test suite. Additional statistical tests indicate the condensed plaintext results in a near-uniform distributed ciphertext across the entire field. The block cipher implemented on an MSP430 offers a faster, more power-efficient alternative to the Advanced Encryption Standard (AES) system. This cryptosystem is a secure, scalable option for IoT devices that must be mindful of time and power consumption.

Local super anti-magic total face coloring on shackle graphs

We define graph G as a nontrivial, finite, connected graph which contains vertex set V (G), edge set E(G), and face set F (G). We also define g as bijective function that mapping vertex, edge, and face labeling to natural number which starting from 1 until |V(G)| for vertex label, from |V(G)| + 1 until |V(G)| + |E(G)| for edge label, and the last for face label from |V (G)| + |E(G)| + 1 until |V (G)| + | E (G)| + |F(G)|. If there are different weights in any neighboring two faces f1 and f2 has w(f1) = w(f2) for f1, f2 G F (G), so g is considered a local super anti-magic total face labeling. A proper face coloring from local super anti-magic total face labeling caused by assigns the color of face weights to local super anti-magic total face coloring. The minimum number of colors needed for local super anti-magic total face coloring is called The chromatic number of the local super anti-magic total face coloring. γlatf (G) can be denoted as the chromatic number of the local super anti-magic total face coloring. Encryption keys can possibly be created from the result of local super anti-magic total face coloring that can be used to construct a modified Affine cipher and Cipher Feedback Mode. As a result, we have one the orem for the chromatic number of local super anti-magic total face coloring and two algorithms for establishing super anti-magic total face coloring on shackle graphs in Cipher Feedback Mode.

Evaluation and Analysis of Interferograms from an InSAR Radar Encrypted by an AES-Based Cryptosystem with The Five Encryption Modes

This paper falls within the framework of the security of satellite images, in particular interferograms from an Interferometric Synthetic Aperture Radar (inSAR) system. The innovation of this work consists in the application of a cryptosystem based on two algorithms Advanced Encryption Standard (AES) and the Rivest, Shamir and Adleman (RSA) encryption algorithm for securing interferograms of inSAR systems. AES employs five encryption modes Electronic Code Book (ECB), Cipher Bloc Chaining (CBC), Cipher FeedBack (CFB), Output FeedBack (OFB), and counter-mode encryption (CTR). The use of the AES algorithm alone can only ensure the confidentiality function. In the proposed cryptosystem confidentiality is ensured by the AES algorithm, authenticity is guaranteed by the RSA algorithm, and integrity is ensured by two parameters; the correlation function between the adjacent pixels and the SSIM parameters (structural similarity index SSIM). For evaluation and analysis of security performance for interferogram encryption, several test metrics are employed. These metrics are: Analysis of histograms of the encrypted interferograms, correlation between the adjacent pixels, between the original interferogram and the encrypted interferogram, SSIM between the original interferogram and the decrypted one. Moreover, we exploit the analysis of resistance to error propagation for the five modes. The obtained results show a superiority of the OFB and CTR modes for the encryption of inSAR interferograms compared to ECB, CFB, and CBC modes. It is noteworthy, that the main criteria that can be used to choose between OFB and CTR for encryption of satellite images are propagation of errors and the complexity material for their locations on the edges of the satellites propagation of errors and the complexity material for their locations on the edges of the satellites. OFB mode is employed in satellites to minimize the number of on-board circuits, which is decisive for satellites. CTR mode is recommended by the CCSDS (Consultative Committee for Space Data Systems) for telemetry (TM) and remote control (TC) encryption.

Color Image Encryption with Cipher Feedback and Coupling Chaotic Map

Based on the classic quadratic map (CQM) with abundant bifurcations and periodic windows, a new 3D improved coupling quadratic map (3D-ICQM) is constructed, and its phase diagram, Lyapunov exponent (LE) and randomness testing by TestU01 demonstrated that it has better ergodicity, more complex nonlinear behavior, larger chaotic range and better randomness. To investigate its application in cryptography, a 3D-ICQM based color image encryption algorithm with round key expansion is designed. To further enhance the randomness of key stream, the hash value of intermediate cipher of the previous round is converted into new initial values and fed back into 3D-ICQM, to generate the key stream for the current round. The security and statistical analyses demonstrated that the encryption scheme has better security performance than several existing algorithms.

Optimized mobility management protocol for the IoT based WBAN with an enhanced security

Today, Wireless Sensor Network (WSN) is widely used for general purposes. With the propagation of the Internet of Things (IoT), security issues arise wherever the healthcare devices are used exclusively for data transfer protocols. These network protocols are easily susceptible to attack. Although it is problematic to save sensing information from the body sensors, the loss of signal messages will often occur in an IoT environment. Thus security is a supreme requirement in health care applications, especially in the case of patient privacy. In this paper, an IoT health care communication system is designed to implement the integration using CoAP based Secure-aware Mobility Management Protocol (CoSMP) in Wireless Body Area Network (WBAN) based IoT environment. The proposed protocol is extremely effective to secure the sensing information of the device node wherever they are moving and additionally, it is accustomed to offer secure data transmission between the node and web client. Our protocol establishes a pairwise key between the networks according to an exact algorithm, namely Advanced Encryption Standard Cipher Feedback Message Authentication Code (AES-CFMAC) algorithm, and handover operation could be authenticated by Elliptic Curve Digital Signature Algorithm (ECDSA). Numerical analysis and performance result imposes the proposed scheme is simulated in terms of network delay and handover delay. Experimental results depict that the proposed protocol has been compared with the previous protocol in terms of security and mobility management. Hence, the numerical result would be evaluated based on the measures of Total Transmission Delay (TTD) on the variation of wireless link delay, sensor node delay, link failure probability delay, hop count between the gateway and WMMS in the network delay with the low delay of 303.55, 1.6, 700 and 80 in ms respectively and also performance measures of Handover Delay (HD) achieves 1212.5, 1.212, 49.46 and 1453.8 in ms respectively. The percentage in terms of using performance measures of TTD and HD is compared between proposed and existing schemes resulted in (COMP = 0.3632%, COMP-G = 0.2712 % and COSMP = 0.2532%) and (COMP = 0.3188%, COMP-G = 0.2421 % and COSMP = 0.2133%) respectively.

Efficient chaotic-based image cryptosystem with different modes of operation

This paper proposes a design of 2-D chaotic Baker map for image encryption which utilizes three modes of operations: 1) the cipher block chaining (CBC) mode, 2) the cipher feedback (CFB) mode, and 3) the output feedback (OFB) mode. The proposed image cryptosystem is characterized by a short encryption time of scalevariant images and a high level of confusion and diffusion due to its shuffling and substitution processes. This is useful in applications such as online streaming of paid videos, in which both the speed of encryption\decryption and a good encryption quality is required. A comparison between the proposed image cryptosystem, the traditional 2-D chaotic Baker map permutation cryptosystem, and the RC6 substitution cryptosystem is presented in the paper. A comparison is held with relevant techniques and the results reveal that the proposed image cryptosystem achieves a high degree of security. It is also more immune to noise than the RC6 cryptosystem and takes less processing time for images with large dimensions than both the chaotic cryptosystem and the RC6 cryptosystem. The superiority of the proposed cryptosystem has been proved for image encryption against the recent techniques from the cryptographic viewpoint.

A Selective Video Encryption Scheme Based on Coding Characteristics

The protection of video data has become a hot topic of research. Researchers have proposed a series of coding algorithms to ensure the safe and efficient transmission of video information. We propose an encryption scheme that can protect video information with higher security by combining the video coding algorithm with encryption algorithm. The H.264/AVC encoding algorithm encodes the video into multiple slices, and the slices are independent of each other. With this feature, we encrypt each slice while using the cipher feedback (CFB) mode of the advanced encryption standard (AES) with the dynamic key. The key is generated by the pseudo-random number generator (PRNG) and updated in real time. The encryption scheme goes through three phases: constructing plaintext, encrypting plaintext, and replacing the original bitstream. In our scheme, we encrypt the code stream after encoding, so it does not affect the coding efficiency. The purpose of the CFB mode while using the AES encryption algorithm is to maintain the exact same bit rate and produce a format compatible bitstream. This paper proposes a new four-dimensional (4-D) hyperchaotic algorithm to protect data privacy in order to further improve the security of video encryption. Symmetric encryption requires that the same key is used for encryption and decoding. In this paper, the symmetry method is used to protect the privacy of video data due to the large amount of video encrypted data. In the experiment, we evaluated the proposed algorithm while using different reference video sequences containing motion, texture, and objects.

Audio Encryption Scheme Using Self-Adaptive Bit Scrambling and Two Multi Chaotic-Based Dynamic DNA Computations

In this paper, a novel scheme for secure audio transmission is introduced. The novelty of this scheme is that it combines four different techniques for audio encryption in the same scheme which makes it more secure: self-adaptive scrambling, multi chaotic maps, dynamic DNA encoding and cipher feedback encryption. Also, it introduces two new designed multi chaotic maps as pseudo random generators that combine five different chaotic maps with eight control parameters. The scheme consists of three phases with three secret keys. The first phase is a self-adaptive bit scrambling where SHA512 of the input audio is computed to be used as a first secret key for cyclic shifting the input audio binary stream which efficiently reduces the strong correlation between neighboring audio samples. The second phase is a dynamic DNA encoding of the scrambled audio by using a second secret key obtained from a pseudo random generator (LCS) using a novel design of multi chaotic maps including Sine, Chebyshev and Logistic map with three control parameters. As DNA encoding provides fast computations and large capacity for data transmission, the third phase consists of two DNA algebraic operations “AND” and “XOR” using a pseudorandom DNA sequence as a third secret key generated by another new designed multi chaotic HLG map which combines Henon, Logistic and Gaussian chaotic maps and has five control parameters. The third phase is structured in a cipher feedback mode and so it achieves strong diffusion and confusion in the encrypted audio. Also combining five different chaotic maps in the proposed scheme increases the number of secret control parameters which achieves a huge key space and so robust strength against brute force attacks. The scheme is evaluated by using different measurements including signal to noise ratio (SNR), peak signal to noise ratio (PSNR), number of samples change rate (NSCR), unified average changing intensity (UACI), root mean square (RMS), crest factor (CF), correlation coefficient, histogram, key sensitivity and key space. From results, it is clear that the scheme is highly secure and stronger than many recent similar audio encryption schemes against different types of attacks.

A Novel Plaintext-Related Image Encryption Scheme Based on Chaotic System and Pixel Permutation

To improve the abilities of image encryption systems to resist plaintext attacks and differential attacks, a novel plaintext-related image encryption scheme based on Josephus traversing and pixel permutation is proposed. In this scheme, the step sizes of the Josephus traversing are associated with the pixel values, and the Josephus traversing method is improved, increasing the dependence of the cipher image on the plaintext image, further enhancing the plaintext sensitivity of the algorithm, and reducing the number of iterations of the index sequence generated by the chaotic system. By segmenting the image and combining a chaotic system, bit XOR and crossover operations between the modules are performed to achieve the effects of confusion and diffusion, and the randomness of the cipher image is improved. Finally, the confusing and spreading characteristics of the algorithm are further enhanced by cipher feedback. The experimental results and security analysis show that the proposed algorithm is sensitive to keys and can effectively resist attacks such as statistical attacks, selective-plaintext attacks and exhaustive attacks. The algorithm has high potential for real-time and secure image applications.

Efficiently Encrypting Color Images With Few Details Based on RC6 and Different Operation Modes for Cybersecurity Applications

Recently, massive research works have been accomplished for augmenting privacy and security requirements for cybersecurity applications in wireless communication networks. This is attributed to the fact that conventional security processes are not appropriate for robust, efficient, and reliable multimedia streaming over unsecure media. Therefore, this paper presents an efficient color image cryptosystem based on RC6 with different modes of operation. The proposed cryptosystem is composed of two phases: encryption and decryption. The encryption phase starts by decomposing the color plainimage with few details into its RGB components, which in turn, are segmented into 128-bit blocks. These blocks are then enciphered using RC6 with an appropriate mode of operation. After that, the corresponding enciphered blocks of RGB components are multiplexed for constructing the final cipherimage. This scenario is reversed in the decryption phase. The performance of the proposed cryptosystem is gauged via simulation using a set of encryption quality metrics. The simulation results reveal that the proposed cryptosystem with cipher block chaining (CBC), cipher feedback (CFB), and output feedback (OFB) modes can efficiently and effectively hide all information of the color images with few details even in the presence of some input blocks with similar data. On the other hand, the results show that the electronic codebook (ECB) mode is not effective at all in hiding all details of images. Finally, the obtained results ensure the applicability of the proposed cryptosystem and its efficiency in encrypting images in terms of security, encryption quality, and noise immunity.

Self-Synchronized Encryption for Physical Layer in Gigabit Ethernet Optical Links

In this work a new self-synchronized symmetric encryption solution for high speed communication systems necessary to preserve the format of the plaintext is proposed, developed and tested. This new encryption mechanism is based on the block cipher operation mode called PSCFB (Pipelined Statistical Cipher Feedback) and the modulo operation. The confidentiality of this mode is analyzed in terms of its IND-CPA (Indistinguishability under Chosen-Plaintext Attack) advantage, concluding that it can be considered secure in the same way as traditional modes are. The encryption system has been integrated in the physical layer of a 1000Base-X Gigabit Ethernet Interface, where the 8b/10b symbol flow is encrypted at line rate. Moreover, an implementation of the proposed system has been carried out in an FPGA (Field Programmable Gate Array) device. Finally, an encrypted optical link has been tested with real Ethernet frames, getting maximum throughput and protecting the data traffic from passive eavesdroppers.

Self-Synchronized Encryption for Physical Layer in 10Gbps Optical Links

In this work a new self-synchronized encryption method for 10 Gigabit optical links is proposed and developed. Necessary modifications to introduce this kind of encryption in physical layers based on 64b/66b encoding, such as 10 GBase-R, have been considered. The proposed scheme encrypts directly the 64b/66b blocks by using a symmetric stream cipher based on an FPE (Format Preserving Encryption) block cipher operating in PSCFB (Pipelined Statistical Cipher Feedback) mode. One of the main novelties in this paper is the security analysis done for this mode. For the first time, an expression for the IND-CPA (Indistinguishability under Chosen-Plaintext Attack) advantage of any adversary over this scheme has been derived. Moreover, it has been concluded that this mode can be considered secure in the same way of traditional modes are. In addition, the overall system has been simulated and implemented in an FPGA (Field Programmable Gate Array). An encrypted optical link has been tested with Ethernet data frames, concluding that it is possible to cipher traffic at this level, getting maximum throughput and hiding traffic pattern from passive eavesdroppers.

Influence of Multiple Encryptions on the Security and Accuracy of Sent and Received Data

Encryption of data using multiple encryptions has been suggested in a range of contexts and can be used to protect the text versus cryptanalysis. Most work on this topic has intensive on the security of multiple encryptions against plaintext – ciphertext attacks, and has displayed creations secure by merging RC5 and CFB algorithm. This research explains in detail the application which it develops to encrypt and decrypt information depending on RC5 algorithm with the cipher feedback (CFB) mode. RC5 is a block cipher which means the same key will be used for both encryption and decryption. The most commonly chosen is the RC5-32/12/16. Cipher text feedback (CFB) is a mode of operation for a block cipher. This application has both server and client’s side which connect to each other using some ports to exchange encrypted and decrypted data by the RC5 algorithm with CFB mode. Clients connect to server to transmit data in a secure channel. The main aim is to simplify and describe the application which it developed using the RC5 and CFB mode and shows the secure usability of those algorithms.

Chaos Based Enhanced RC5 Algorithm for Security and Integrity of Clinical Images in Remote Health Monitoring

The demand for remote health monitoring will significantly increase in the near future due to a decrease in the doctor/patient ratio as the world population grows. In remote health monitoring, one of the major goals is to send patient's data to clinical experts at geographically distant locations. In this scenario, the importance of implementing security on patients' clinical information increases, so that this could not be either changed or read by an unauthorized person. Rivest Cipher (RC5) algorithm is a secure and simple encryption algorithm. Due to its simplicity, fast encryption, and low memory requirements, it is considered as a suitable block cipher for resource constraint environments, such as body area networks (BAN), although it can be broken by various attacks due to poor diffusion. In this paper, we propose a chaotic-based key scheduling algorithm for the RC5 in which round keys are generated based on 2-D chaotic maps and used as a symmetric key during the encryption and decryption process. Cipher feedback mode is adapted to further increase the diffusion property of the cipher. This chaos-based key is very difficult to trace, and the cipher is extremely hard to break. A strict security analysis of the proposed cipher is performed against several attacks. The experimental results have shown that the impact of this approach is significantly better than the conventional security mechanisms in case of BAN when applied to critical clinical images.