As my country's popularity, computer and communication technologies have been widely developed and applied in our country, so that we need more and more urgent for our security storage, safety handling, and secure transmission. Especially in the Internet, and personal communication, personal electronic ID card, office automation, email, electronic automatic transfer payment system, and automatic retail business network establishment and implementation, information security issues have been very prominent, and can solve An effective means of this problem is to use modern cryptographic technology.
The application of the password can always be taughtted long ago, but for modern cryptography, it is the promulgation implementation of the "New Direction of Cryptography" in the 1970s and the promulgation of the US Data Encryption Standard DES. Since then, the prelude of commercial password research has been uncovered. The practical cryptographic system is basically carried out in two directions, ie the public key cryptographic system represented by RSA and the secret key packet password system represented by DES. The packet password has the characteristics of fast, easy to standardize and facilitates hardware and software, which is usually the core system of data encryption, digital signature, authentication, and key management in information and network security. It has the most in the field of computer communication and information system security. A wide range of applications.
In the history of this modern packet password study, people have a fruitful research results in this regard. Mandarities include three aspects: the design principle of group password, the security analysis of group passwords and the statistical performance test of packet passwords.
For packet passwords, in early research, some similar algorithms are introduced, such as Loki, Feal, GOST, etc. In the 1990s, people's research on DES algorithm, particularly differential cryptanalysis and linear cryptanalysis, forcing people to study new cryptographic structures. The IDEA password breaks the monopoly situation of the DES class password. Subsequent Square, Shark, Safer-64, which uses a very clear replacement-replacement (SP) network, which gives the most differential feature probability and optimum linearity. The boundary of approximation of the advantage has proved the security of differential cryptographic analysis and linear cryptographic analysis.
AES collection set off a new climax of group password research, 15 AES candidate algorithms reflect the level of current group password design, or a summary of research results in recent years.
The overall structure of the current group password can be divided into Feistel structures (such as CAST-256, DEAL, DFC, E2, etc.), SP networks (such as Safer , Serpent, etc.) and other cryptographic structures (such as Frog and HPC). The addition is similar to the implementation advantage of the Feistel type password, but it seems to be a little slow in the password, for example, two rounds can change each bit of the input. The network structure of the SP is very clear, and S is generally referred to as an aliasing layer, which is mainly confusing. P is generally referred to as a diffusion layer, mainly a diffusion effect. After classifying certain cryptographic indicators of S and P, designers can estimate the ability of SP type password to resist differential password analysis and linear cryptographic analysis. Compared to the FEISTEL network, the SP network is faster, but the SP password is usually not similar.
The current discussion of group password security mainly includes differential cryptographic analysis, linear cryptographic analysis, and powerful attacks. In theory, differential cryptographic analysis and linear cryptographic analysis is the most effective way to attack the group password, and sincerely, a powerful attack is the most reliable method of attacking the packet password. So far, there have been a large number of documents to discuss the security of various group passwords, while launching a variety of analytical methods such as truncation differential analysis, nonlinear cryptographic analysis, and interpolation attacks. Since the announcement of the AES candidate algorithm, many experts and scholars at home and abroad are committed to the safety analysis of candidate algorithms, which is expected to launch some new attack methods, which will undoubtedly promote the development of group passwords. Group passwords are an important research branch in modern cryptography, with a wide range of practical backgrounds and important theoretical values. There are still many theories and practical problems in this field to continue to study and improve. These issues include: how to design a secure password algorithm; how to enhance the security of existing algorithms and its working mode; how to test the security of the password algorithm; how to design a secure password component, such as S-box, diffusion layer, and secret Key diffusion algorithm, etc.
