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| On the Pseudorandomness of the Lai-Massey Scheme |
| Guo Rui Jin Chen-hui |
| PLA Information Engineering University, Zhengzhou 450004, China |
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Abstract The pseudoranness of the Lai-Massey schme is studied in this paper. First, itis proved that if σ is an affine almost orthomorphism, 3-round Lai-Massey scheme can not reach the pseudorandomness, which is a counterexample of the Lai-Massey scheme designer's result. Then, it is proved that at least 3-round Lai-Massey scheme is need for the property of pseudorandomness when the bijective σ is an arbitrary orthomorphism, and at least 4-round Lai-Massey scheme is need for the property of super pseudorandomness when the bijective σ is an orthomorphism. From the above results, it is preferable to design a bijective σ which is nonlinear orthomorphism or almost orthomorphism to construct the Lai-Massey scheme with better pseudorandomness.
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Received: 20 June 2013
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Corresponding Authors:
Guo Rui
E-mail: guorui201@sohu.com
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2014, Vol. 36 
