The current de-facto routing protocol over WSN developed by IETF Working Group (6LOWPAN) named as Routing Protocol for Low Power and Lossy networks (RPL) [1], to enable IPv6 packets carrying over IEEE 802.4 and to empower the usage of IoT over WSN. Because of the potential large networks, number of nodes and the fact that multiple coexisting applications will be running in the same physical layer, RPL in the network layer faces throughput challenges. For the purpose of overcoming these problems many researchers focused on multipath solutions including a Back-Pressure routing protocol for data collection called BackIP [2], however it shows a superior throughput performance, BackIP have shortcomings of higher delay and limited applicability. In this paper, we introduce a node metric based on nodes Queue Backlogs for RPL protocol, which leads to better throughput performance while maintaining the delay and the ability to use with the different network applications. This metric depends on the Packet Queue length of the nodes with the consideration of other link and node metrics, like ETX or Energy usage, leading to better load balancing in the network. Moreover we discuss the needed design changes to enable our metric to perform in an efficient way.

The advances recently seen in data compression, and communication systems, have made it viable to design wireless image transmission systems. For many applications such as confidential transmission, military and medical applications, data encryption techniques should be also used to protect the confidential data from intruders. For these applications, both encryption and compression need to be performed to transmit a message in a fast and secure way. Further, the wireless channels have fluctuating channel qualities and high bit error rates. In this paper, a new scheme based on encryption and channel coding has been proposed for secure image transmission over wireless channels. In the proposed scheme, the encryption process is based on keys generator and Chaotic Henon map. Turbo codes are utilized as channel coding to deal effectively with the channel errors, multipath signal propagation and delay spread. Simulation results show that the proposed system achieves a high level of robustness against wide different of attacks and channel impairments. Further, it improves image quality with acceptable data rates.

Bitcoin is a peer-to-peer electronic cash system largely used for online financial transactions. It gained popularity due to its anonymity, privacy, and comparatively low transaction cost. Its wallet heavily relies on Elliptic Curve Digital Signature Algorithm (ECDSA). Weaknesses in such algorithms can significantly affect the safety and the security of bitcoin wallets. In this paper, a secure key management wallet was designed based on several changes in the wallet parts. In the cold wallet, we employed an image-based passphrase to achieve a strong entropy source of master seed. The hot wallet, the proposed key_ Gen algorithm is modifying to the key generation step of the ECDSA that it is to generate a fresh key pair at each transaction. The final part ensures recovering all keys on both hot and cold wallets without daily backups in case of losing the wallet. The findings prove that the proposed cold wallet is resisting against a dictionary attack and overcoming the memorizing problem. The proposed hot wallet model acquires good anonymity and privacy for bitcoin users by eliminating transaction likability without additional cost. The execution time for signing a transaction of the proposed model is~70 millisecond, which is then important in the bitcoin domain.

The study of cryptography applications in chaotic system have been exponentially increasing in the recent years. Depending on the sensitivity to initial conditions, chaotic systems are characterized, similarity to continuous broad-band power spectrum and random behavior. The chaotic system is high sensitive to the initial condition and is a high complex nonlinear dynamic system. The chaotic sequence is unpredictable and extreme sensitivity to initial conditions. There are many applications to the chaotic system in several methods, image compression, encryption, modulation and digital communication system. In this paper, an algorithm based on Discrete Cosine Transform (DCT) has been introduced by using Henon map to get the scheme of chaos image encryption. The level of security is very high and this algorithm can improve small key space.A new chaotic algorithm is presented to get rid of the problem of the weakness of security in one dimensional chaotic cryptosystems and small key space based on a new chaotic algorithm, which uses two dimension linear functions instead of one dimension.