Title:
CIPHERING CIRCUIT
Document Type and Number:
Japanese Patent JP3148790
Kind Code:
B2
Abstract:
PURPOSE: To improve the safety and the processing speed by providing the constitution in which a key data storage means, that beforehand stores key data, can not be directly accessed from the external.
CONSTITUTION: In a conventional ciphering circuit constitution, a key register is replaced by a key address register 8 and a key memory control circuit 9 and a key memory 10 are added. In order to prevent the deterioration of the safety by an external key input, a ciphering key is beforehand stored in the memory 10. When a key address is inputted from an external, a key corresponding to the inputted key address is taken out from the memory 10 by the circuit 9 and the key is set in the register 8. Thus, the memory 10 can not be accessed from an external controller 2. Therefore, the controller 2 sets a key without referring to the key.
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Inventors:
Naoya Torii
Takayuki Hasebe
Yoko Okazaki
Toshifumi Fujimoto
Katsumi Kobayashi
Takayuki Hasebe
Yoko Okazaki
Toshifumi Fujimoto
Katsumi Kobayashi
Application Number:
JP4447994A
Publication Date:
March 26, 2001
Filing Date:
March 15, 1994
Export Citation:
Assignee:
富士通株式会社
International Classes:
H04L9/22; G09C1/00; H04L9/10; (IPC1-7): H04L9/10
Domestic Patent References:
| JP1212041A |
Attorney, Agent or Firm:
Tadahiko Ito