| 摘要 |
PURPOSE:To reduce the processing speed of an enciphering device by enciphering solid document data with specific length which arrives successively by addition to respective bits of key stream data stored in a buffer memory, and allowing a block encipher to encipher to encipher the next solid document data simultaneously. CONSTITUTION:When a header detector 1 detects the 1st bit of solid document data (d), block data (a0-a4) set in a shift register SFR2 are enciphered by a block enciphering device 3 and key data (e0-e4) are written in a buffer memory 15. Solid document data (d0-d4) are added to the key data from the memory 15 successively and then transmitted. The 1st output c0 of an exclusive OR circuit 6, on the other hand, is inputted to the SFR2 and the key data (e5-e9) corresponding to the next solid document data (d5-d9) are enciphered during the transmission by using block data (c0 and a1-a3) and stored in a buffer memory 16. The key data are inputted to the buffer memories 15 and 16 alternately. |
