| 摘要 |
PURPOSE: An intermediate value creating circuit being used in an SHA(Secure Hash Algorithm)-1 is provided to increase an operation speed of an intermediate value(median(Wt)) generating circuit and decrease an electric power consumption of the median(Wt) generating circuit by decreasing the number of all registers which store a median(Wt) of an SHA-1 hash function. CONSTITUTION: In an SHA-1 hash function median(Wt) generating circuit, a buffer(21) receives data which are padded by 512-bit, creates and stores 16 blocks by 32-bit. The first selection circuit(23) responds to the first control signal and selects output signals of the buffer(21) or the median(Wt). A median(Wt) storing block(27) stores an output signal of the first selection circuit(23). The second selection circuit(29) responds to the second control signal, and selects and outputs four medians(Wt) stored in the median(Wt) storing block(27). A median(Wt) calculation circuit(35) outputs the median(Wt) created by performing a logical operation of the outputs of the second selection circuit(29) to the first selection circuit(23). The third selection circuit(31) responds to the third control signal, and selects and outputs the median(Wt) stored in the median(Wt) storing block(27).
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