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Generic Complex Programmable Logic Device Board
Published in Hafiz Md. Hasan Babu, VLSI Circuits and Embedded Systems, 2023
The worldwide system for mobile communications (GSM) is a second-generation (2G) mobile phone system that has made mobile communications available to the general public. In many developed nations, the number of mobile phone customers outnumbers the traditional telephone network. GSM and the security architecture that underpins it were created in the 1980s. Because it is extensively used and has become pervasive in most nations across the world, its reach is still expanding. The stream cipher A5/1 is used to protect over-the-air communication (GSM). This method gives a fair level of assault protection. There are three linear feedback shift registers in it. (LFSR). The lengths of the registers are 19, 22, and 23. The XOR of the three LFSRs is the output. The clock control on the A5/1 is changeable. Each register is timed using its own middle bit, which is XORed with the inverse threshold function of all three registers' middle bits. Two of the LFSRs clock are usually used in each round. Fig. 22.7 depicts the anatomy of A5/1.
Cyber Security in Terms of IoT System and Blockchain Technologies in E-Healthcare Systems
Published in Sourav Banerjee, Chinmay Chakraborty, Kousik Dasgupta, Green Computing and Predictive Analytics for Healthcare, 2020
Sudipta Paul, Subhankar Mishra
From Figure 7.8, we can easily understand the process of symmetric key cryptography between two IoT devices. Common symmetric key cryptography ciphers are AES, DES, Triple DES, Blowfish, Camelis, IDEA, etc. From Figure 7.8 it is evident that the main concern in this whole process lies in choosing a key and passing it securely through secured channel. For the “choosing” part, an assumption is made that both the devices know the scheme of their encryption and decryption process beforehand. Therefore, the only data that has to be well-hidden or securely hidden from outsider is the “key”; in Figure 7.8 it is e. The decryption key can be easily calculated from the encryption key. Therefore, the load in storage of key in terms of data size is reduced in this process. There are two types of symmetric key cryptography: block ciphers and stream ciphers. The main difference between block ciphers and stream ciphers is that stream ciphers are a subset of block ciphers with a block length of one byte, but the reverse is not true. As IoT devices have very limited data buffering, therefore the stream cipher is more efficient for IoT devices. An example of a block cipher is Fiestel Cipher and of a stream cipher, Vernam Cipher.
Stream Ciphers
Published in Alfred J. Menezes, Paul C. van Oorschot, Scott A. Vanstone, Handbook of Applied Cryptography, 2018
Alfred J. Menezes, Paul C. van Oorschot, Scott A. Vanstone
Stream ciphers are an important class of encryption algorithms. They encrypt individual characters (usually binary digits) of a plaintext message one at a time, using an encryption transformation which varies with time. By contrast, block ciphers (Chapter 7) tend to simultaneously encrypt groups of characters of a plaintext message using a fixed encryption transformation. Stream ciphers are generally faster than block ciphers in hardware, and have less complex hardware circuitry. They are also more appropriate, and in some cases mandatory (e.g., in some telecommunications applications), when buffering is limited or when characters must be individually processed as they are received. Because they have limited or no error propagation, stream ciphers may also be advantageous in situations where transmission errors are highly probable.
A partial image encryption scheme based on DWT and texture segmentation
Published in Cogent Engineering, 2022
Zainab Noori Ghanim, Suha Abdul Raheem Khoja
RC4 is symmetric key stream cipher with byte-oriented operations and a variable length key which ranges from 1 to 256 bytes. The algorithm consists of three steps, Initialization, Initial Permutation and Stream Generation. Under the initialization step, two vectors, namely S and T, are initialized. The state vector S is initialized with the numbers from 0 to 255, i.e. S [0], S[1] (Sreelajaa & Vijayalakshmi Paib, 2012),S [255]. The T vector is filled with the key values if the key length is 256 bytes; otherwise the key is repeated to fill the 256 bytes of T. In the Initial Permutation step, the T vector is used to permute the values of the vector S by using a swap operation only. At the end of this step the vector T is no longer used. The input to the Stream Generation step is the permuted state array which will be further permuted at this step with itself by swapping each S [i] with another byte of S to generate the final key stream. Finally the generated key stream is XORed with the plaintext to generate the cipher text (K. Ahmed & Mohammed, 2017; Stallings, 2011).
S-box design method based on improved one-dimensional discrete chaotic map
Published in Journal of Information and Telecommunication, 2018
Cryptographic algorithms used for encryption are divided into two main categories: stream and block ciphers. Stream ciphers are designed to encrypt one bit at the time while block ciphers operate on a group of bits of fixed length which is called a block. Shannon's property of confusion is essential for block ciphers because it obscures connection between secret key used for encryption and encrypted bits. Substitution box (S-box) is important nonlinear component used in block ciphers to achieve confusion property. S-box have some number of bits as a input and transform these bits to some number of output bits. Although number of input and output bits is not necessarily the same, recent block ciphers mostly use such S-boxes. From mathematics perspective, an S-box is a nonlinear mapping , where is the vector space of m elements from GF(2).
Efficient Key Generation Techniques for Securing IoT Communication Protocols
Published in IETE Technical Review, 2021
Amol K. Boke, Sangeeta Nakhate, Arvind Rajawat
Stream cipher encrypts the single bit (byte or word) at a moment and establishes feedback because of which the key is repeatedly changing. Data coming as output from stream cipher are periodic in nature and hence predictable. Although it does not have a transmission problem, it does suffer from propagation problem i.e. single distorted bit in the transmission side will result in several errors/distorted bits in the receiver side [30]. Some of the examples of stream ciphers are given in Figure 3.