ABSTRACT
Symmetrical cryptosystem is an important branch of modern cryptography, with
its appearance and development there are wide applicant background and theorial
value. There are lot theorial and applicant problems need to be studied and optimized,
such as: how to design a provable safe cryptosystem, how to strengthen the safty of
algorithms and working modules which are already available, how to test the safty of
a cipher algorithm, how to design safe components of a cryptosystem, as S-boxes,
diffusing layers, and key-expanding processes, etc.
The general architecture of symmetrical cryptosystem at present can be sorted as
Feistel, SP network and
other architectures. Symmetry is the most distinct character of Feistel,
while SP network has a good deffuse capability. AES inherited SQUARE in
designation, and added in a lot of matrix operations. This causes a bit different
between encryption and decryption, but it optimizes the efficiency of the algorism.
AES is a rapid progress in cryptosystem development, however, it needs to be
ameliorated yet. The efficiency of AES may be boosted, and new working module is
also necessary to be developed.
This paper introuduces the theory of semmetrical cryptography and the working
process of AES algorithm, improves a conventional means of increasing the
encrypting speed based on table-looking-up method, proposes its optimized algorism,
which can greately increase the encrypting / decrypting speed, or save on memory
space. Besides, a high-efficient method of generating S-box is proposed.
And, the working module of AES is also a hot point of researching at present. A
working module based on random block length is designed taking the advantage of
Rijndael that it has a obvious agility in the length of block and cipher key, and this
module can strengthen the safty of Rijndael algorithm. that completely crack this
module is a imporsable case at the applicant level of present is proved. This module is
also able to be composed with CFB, CBC, and other available modules, strengthening
safty and remaining aviable merits. And, other characters of this module are analysed
in this paper, based this, some advices of applying it are proprsed.
Keywords: symmetrical cryptography, Rijndael, finite field, working module
Summary
catalog
Chinese Abstract I
English Abstract II
Introduction 1
symmetric key encryption algorithm 1 Introduction 4
1.1 symmetric cipher algorithm system 4
1.2 password mode 4
1.2.1 Electronic Code of the mode 4
1.2.2 Cipher Feedback Mode 4
1.2.3 Cipher Block Chaining mode 5
1.2.4 Output feedback mode 6
1.3 Summary 7
2 symmetric algorithm attack 8
2.1 Linear cryptanalysis 8
2.2 Differential cryptanalysis 11
2.3 12
2.3.1 Energy Analysis Energy Analysis principle 12
2.3.2 Differential Power Analysis 12
2.4 Summary 14
3 Rijndael algorithm 15
3.1 Rijndael algorithm About 15
3.2 Rijndael algorithm is the mathematical basis of 19
3.2.1 addition operation 20
3.2.2 Multiplication 20
3.3 Rijndael encryption and decryption process 20
3.4 Rijndael in the transformation and the four design principles 21
3.4.1SubBytes 22
3.4.2ShiftRows 23
3.4.3MixColumns 23
3.4.4 key addition 23
3.4.5 key arrangement 24
3.5 Summary 26
4 AES algorithm to improve the long word on the platform to achieve 27
4.1 the process of achieving 27
4.2 The process of optimization 28
4.2.1 round transformation to further improve the 28
4.2.2 S-box generates 29
4.3 Summary 30
5 A working model of the Rijndael algorithm 31
5.1 Extended operating modes Jane 31
5.2 RBC mode and other modes of combination of 33
5.2.1 RBC-CFB mixed-mode 33
5.2.2 RBC-CBC mixed-mode 35
5.2.3 RBC-OFB mixed-mode 36
5.3 Performance Analysis 37
5.3.1 Safety 37
5.3.2 Efficiency 37
5.3.3 Other features 38
5.4 Summary 38
6 thank full summary 39
40
41
References Appendix 42
AES-based encryption mechanism to achieve
Paper ID: TX043 papers Words: 23746, Page: 57
symmetric cryptography, modern cryptography is an important branch of its birth and development have a wide range of context and important theoretical value. Currently this area there are many theoretical and practical issues to be continued research and improvement. These issues include: how to design a provably secure cryptographic algorithms; how to strengthen the existing algorithm and its mode of security; how to test the security of cryptographic algorithms; how to design a secure password components, such as S-box, and the diffusion layer key expansion algorithm. Currently used block cipher can be divided into the overall structure of Feistel structure, SP structure of the network and other passwords. Feistel structure of the biggest advantages is the easy encryption and decryption to ensure similarity; SP network is spread performance is better. SQUARE features AES followed with a SP network, and extensive use of encryption and decryption process matrix operations, this makes the encryption and decryption process is slightly different, but significantly increased the efficiency of algorithms. Although the design of the AES block cipher system in the development of a qualitative leap, but there are still research and improvement. AES on multiple platforms to achieve the efficiency to be further improved,
mbt shoes ireland, while the new encryption mode has yet to be studied. This paper briefly introduced some of the basic symmetric cryptography and AES algorithms working knowledge of the process, according to the AES algorithm is characterized by a large number of matrix operations, improved look-up table based on the traditional computing methods to improve the speed of encryption and decryption,
tory burch outlet, given the time and space optimization to achieve: the time of the optimization algorithm can improve the speed of AES encryption and decryption algorithms,
p90x workout schedule, space optimization can improve the speed on the premise of saving the cost of storage; also presented the S-box hardware platform to generate efficient way. In addition, AES mode of operation is currently one of the hot. Authors use the Rijndael algorithm and key length in the packet length on the flexibility of the design of a randomized encryption and decryption based on the work mode, this mode can improve the security of the Rijndael algorithm work; paper demonstrated that in the current application message lengths, this model is not completely decrypted event; The model also with the CFB, CBC and other original model portfolio, while maintaining the advantages of the original model based on the greatly increased security; In addition, the paper analyzes this modes of the other features of this mode of application environments are suggested. Keywords: symmetric encryption algorithm, Rijndael, finite fields,
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