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<p>With the rapid growth of the Internet and mobile devices, the need for hidden communications has significantly increased. Steganography is a technique introduced for establishing hidden communication, Most steganography techniques have been applied to audio, images, videos, and text. Many researchers used steganography in Arabic texts to take advantage of adding, editing or changing letters or diacritics, but lead to notable and suspicious text. In this paper, we propose two novel steganography algorithms for Arabic text using the Holy Quran as cover text. The fact that it is forbidden to add, edit or change any letter or diacritics in the Holy Quran provides the valuable feature of its robustness and difficulty as a cover in steganography. The algorithms hide secret messages elements within Arabic letters benefiting from the existence of sun letters (Arabic: ḥurūf shamsīyah) and moon letters (ḥurūf qamarīyah). Also, we consider the existence of some Arabic language characteristics represented as small vowel letters (Arabic Diacritics). Our experiments using the proposed two algorithms demonstrate high capacity for text files. The proposed algorithms are robust against attack since the changes in the cover text are imperceptible, so our contribution offers a more secure algorithm that provides good capacity.</p>

In recent years, revolution of development was exceedingly quick in the Internet. Nevertheless, instead of only linking personal computers, mobiles and wearable equipment's, Internet growths from a web binding to true world physical substances that is indicated to novel connotation, which is labeled as Internet of Things (IoT). This concept is utilized in many scopes like education, health care, agriculture and commerce. IoT devices are presented with batteries to have independence from electric current; consequently, their working time is specified by the total time of the power of these batteries. In many IoT applications, data of IoT devices are extremely critical and should be encrypted. Current encryption approaches are created with a high complexity of an arithmetical process to provide a high level of security. However, these arithmetical processes lead to troubles concerning the efficiency and power consumption. ChaCha cipher is one of these approaches, which recently attracted attention due to its deployment in several applications by Google. In the present study, a new stream cipher procedure is proposed (called Super ChaCha), which performs low duty cycles for securing data on IoT devices. The proposed algorithm represents an improved revision to the standard ChaCha algorithm by increasing resistance to cryptanalysis. The modification focuses on rotation procedure which has been changed from a fixed constant to a variable constant based on random value. Also, the inputs of the cipher are changing in the columns form followed by diagonals form to zigzag form and then by alternate form to provide improved diffusion in comparison with the standard ChaCha. Results regarding the security illustrate that Super ChaCha needs 2512 probable keys to break by brute-force attack. Furthermore, the randomness of Super ChaCha successfully passed the five benchmark and NIST test.

Salsa (20) cipher is speedier than AES cipher and its offered superior security. Salsa (8) and Salsa (12) are specifiedfor apps wherever the grade of security is less necessary than speed. The concept of this research is to suggest super salsakeystream utilizing various volumes matrices size (array (4, 4), array (4, 8), array (4, 16)) are used to increase the complexity ofkey stream and make it more reluctant to linear and differential attacks. Furthermore, in each iteration, the diffusion ofgenerated keystream will increase due the effect of changing the volume acting for one element of the array is not fixed. Thegenerated keys of the suggested Super SALSA keystream are depicted as simple operations and a high hardiness randomlykeystream by exceeding the five benchmark tests. Likewise, it's presenting a situation of equilibrium between complexity andspeed for Salsa (8, 12 and 20).