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.INDEX TERMS Audio encryption, DNA encoding, chaotic maps, security analysis.

In this paper, a novel scheme for secure and real time image transmission is introduced. The scheme uses a block-based elliptic curve (BBEC) public key encryption as a first stage of encryption so it solves the key distribution and management problem of symmetric key encryption in an efficient method. Then the security of first stage BBEC encryption is enhanced through a second stage of encryption which XOR the BBEC first stage output with a pseudo random sequence generated by a new designed multi chaotic pseudo random generator STH. It merges Sine, Ten and Henon maps (STH) and so it has five secret control parameters which increase the key space and hence the scheme security against brute force attacks. Both the key of the first stage BBEC image encryption and the control parameters of the second stage STH depend on two parts: EC Diffie-Hellman shared secret key and the input plain image itself which provides a good randomness and achieves a strong resistance against chosen plaintext attacks. After the two stages of encryption, the encrypted image is digitally signed in an efficient method to achieve integrity, authentication and non-repudiation. The results prove that the proposed scheme is more secure and faster than some other recent EC based schemes. It has low correlation, huge key space; key-dependent pixel value replacement and can resist statistical, differential and noise attacks.

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Hash functions are considered as the core of cryptography, which are the basic technique used for data security. Cryptographic hash functions also can be used to achieve the integrity of large data such as the data stored in a hard disk and set of financial data. So, in the era of large data and increasing capacity of data in applications, fast hash schemes with parallel operations are extremely desirable which effectively increases the computational speed. Functions of random behavior like chaotic maps are used in hash functions to generate the fixed length message digest from the original message. This paper proposes a parallel hash algorithm based on multiple chaotic functions by mixing logistic map, tent map, and sine function. In the proposed scheme the structure of coupling lattice is changed and using diamond lattice as new structure. This algorithm is flexible to generate 128, 256 or longer hash value. The simulation analysis such as hash distribution, key sensitivity, confusion and diffusion statistical properties, and collision resistance are executed. The results demonstrated that the proposed hash is an efficient, simple and fast algorithm comparing with some recent hash algorithms based on chaotic maps.

Encryption of medical image is very important subject especially in wireless body area networks (WBAN) applications where the devices have many limitations in memory size, energy and computation capabilities. In this paper an image encryption scheme is introduced to be suitable for this limitations. The scheme consists of two phases. Firstly, the patient information (as name, age, ..etc) is hidden in the patient medical image (as x-ray, MRI, ..etc) using Least Signification Bit technique to reduce the capacity of data encrypted and make this information visually unavailable to unauthorized personnel. Secondly, the patient’s medical image is encrypted using DNA coding rules and a new multi chaotic map system. DNA coding improves computational speed and provides large capacity for data transmission while the new multi chaotic map consists by merging Henon, Sin and Ten map (HST) to produces pseudo random sequences with more chaotic characteristics. Results show that this scheme has a good peak signal to noise ratio, low correlation, huge key space, key-dependent pixel value replacement and can resist statistical and differential attacks.

Proxy signcryption scheme allows an original signer to delegate his signing power to a proxy such that the latter can signcrypt a message on behalf of the former. In this paper, a new proxy signcryption scheme is proposed based on Discrete Logarithm Problem (DLP) and Diffie-Hellman Problem (DHP) with a reduced computational cost compared to other schemes in literature. The proposed scheme achieves public ciphertext authentication as the signcrypted message before being accepted, the receiver first verifies the signature. This property is very useful as the receiver can filter some incorrect ciphertext before decrypting it which achieves more efficient unsigncryption. Also, a variant of the main scheme that works over elliptic curves will be considered, since it has proven to provide better security with shorter keys and hence less storage requirements which makes it more suitable for resource constrained devices such as pagers and mobile phones. Numerical examples have been given with Mathematica to emphasize the ease of its practical use.

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