Rohm Co., Ltd.

Masao Takayama

Yoshikazu Fujimori

Hiroshi Nozawa

Shinzo Koyama

The present invention aims at providing a novel enciphering and deciphering apparatus and an enciphering and deciphering method related thereto, which are respectively capable of contracting the time required for enciphering and deciphering processes and decreasing the number of logic gates provided in the apparatus. Essentially based on an equation X=1+&#x3a3;((J=1, i)C&#xb7;X) and also based on an initial value consisting of a group of power raising values Xcorresponding to j=1 through m in relation to k&#x2212;1=k0, an arithmetic operating unit 21 seeks a second expression Yby serially computing a group of power raising values Xcorresponding to i=1 through m in relation to one unit of k shown in the above equation in a range from k=k0+1 up to k=k1 by applying binomial coefficients stored in a coefficient memory unit. Accordingly, once those binomial coefficients corresponding to predetermined integers n and m are stored in memory, thenceforth, it is possible to contract the time required for executing an enciphering or deciphering process related to identical integers n and m.

Enciphering and deciphering apparatus, and enciphering and deciphering method

A coding-decoding device and a coding-decoding method that take less time for coding and decoding are provided while using less number of logic gates. A memory devicesubstantially stores b pieces of conversion logic equations produced with a conversion logic equation producing device. An operation devicehas a programmable hardware logic circuit to constitute logics sequentially according to plural execution unit logic equations obtained by dividing b pieces of conversion logic equations stored in the memory deviceinto execution units for respective execution unit logic equations using the hardware logic circuit. Besides, the operation devicesequentially divides and calculates the second sentences from the first sentences according to the constituted logics. An output devicecollects and outputs the second sentences calculated with the operation device

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Kyoto, Japan

Masao Takayama