The weak point of the existing block encryption scheme is that the plain text or encryption key could be easily exposed differential cryptanalysis or linear cryptanalysis, which is mostly used for decoding block encryption. This is because the encryption schemes have been designed for the fixed size encryption key. Another weak point of the existing block encryption algorithm is that it has a fixed permutation table and fixed number of encryption rounds.In order to overcome these weaknesses, an encryption algorithm using unlimited size of key and dynamically changing permutation table should be designed. A new encryption technique called Variable size Block Encryption using Dynamic-key Mechanism (VBEDM), which is designed with unlimited key size, dynamically changing permutation table based on the encryption key and variable block size for each round. To make the cryptanalyst hard to expose the plain text, from the array of compression algorithms the VBEDM uses a compression technique based on key. The compression used is not for compressing the text but for strengthening the encryption method. Because of its dynamic functionality in input block size, key size, permutation, number of rounds and compression it makes the crypt analyst too hard to analyzing the cipher text. This algorithm also uses a compression technique from an array of compression algorithm resulting in more confusion to the analyst.

White‐box cryptography aims at implementing a cipher to protect its key from being extracted in a white‐box attack context, where an attacker has full control over dynamic execution of the cryptographic software. So far, most white‐box implementations exploit lookup‐table‐based techniques and have been broken because of a weakness that the embedded large linear encodings are cancelled out by compositions of lookup tables. In this paper, we propose a new lookup‐table‐based white‐box implementation for the Chinese block cipher standard SM4 that can protect the large linear encodings from being cancelled out. Our implementation, which can resist a series of white‐box attacks, requires 32.5MB of memory to store the lookup tables and is about nine times as fast as the previous Xiao–Lai white‐box SM4 implementation. Copyright © 2015 John Wiley & Sons, Ltd.

Industrial robots have advantages in the processing of large-scale components in the aerospace industry. Compared to CNC machine tools, robot arms are cheaper and easier to deploy. However, due to the poor consistency of incoming materials, large-scale and lightweight components make it difficult to automate robotic machining. In addition, the stiffness of the tandem structure is quite low. Therefore, the stability of the milling process is always a concern. In this paper, the robotic milling research is carried out for the welding pre-processing technology of large-scale components. In order to realize the automatic production of low-conformity parts, the on-site measurement–planning–processing method is adopted with the laser profiler. On the one hand, the laser profiler hand–eye calibration method is optimized to improve the measurement accuracy. On the other hand, the stiffness of the robot’s processing posture is optimized, combined with the angle of the fixture turntable. Finally, the experiment shows the feasibility of the on-site measurement–planning–processing method and verifies the correctness of the stiffness model.