Matsushita Electric Industrial Co., Ltd.

Yasuo Okumura

Takatoshi Ono

Natsume Matsuzaki

Makoto Tatebayashi

Syunji Harada

Takeshi Saijo

A multi-word arithmetic device, capable of executing a variety of types of multi-word arithmetic required for elliptic curve cryptology, includes the following. A memory, formed from two dual-port memoriesand, temporarily stores n-word integers on which calculation is performed, and a calculation result. An arithmetic unitexecutes two or more types of calculation, including addition and multiplication, on each word, and outputs a one-word result. A memory input/output unitsupplies a maximum of three pieces of one-word data from the memoryto the arithmetic unit, while simultaneously storing a one-word calculation result from the arithmetic unitin the memory. A control unitcontrols the arithmetic unitand the memory input/output unitso as to have the arithmetic unit execute one of modular addition and Montgomery reduction on n words.

Multi-word arithmetic device for faster computation of cryptosystem calculations

A message receiving apparatus for receiving messages from a message transmitting apparatus generates first data for producing a display which urges a user of the message transmitting apparatus to input a message, and generates second data within the first data for specifying a conversion type for secret communication of the message. The message receiving apparatus sends the first data including the second data to the message transmitting apparatus and subsequently receives the message from the message transmitting apparatus. The message transmitting apparatus for transmitting messages to the message receiving apparatus receives the first data for producing the display and the accompanying second data for specifying the conversion type and produces the display according to the first data. On receiving the message inputted by the user in response to the display, the message transmitting apparatus converts the input message according to the second data and transmits the converted message to the message receiving apparatus.

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Moriguchi, Japan

Yasuo Okumura