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Title:
KEY RECOVERY CONDITION CIPHERING DEVICE AND DECODER
Document Type and Number:
Japanese Patent JPH1127254
Kind Code:
A
Abstract:

To add a key recovery conditions having relatively complicated contents to key information.

In adding key recovery conditions, a hashed value (h) obtained by hashing a text M and inputted key recovery conditions RC are combined; these combined results RCh are ciphered with a random number key Kr to generate a Kr(RCh); Kr is separately ciphered by separate keys K1, K2,..., to generate Kn, K1(Kr), K2(Kr),..., Kn(Kr) and are combined with the Kr(RCh). In decoding the key recovery conditions, the Kj(Kr) obtained by the inputted additional information is decoded with the separate key Kj for generating the random number key Kr, while Kr(RCh) obtained from the inputted additional information is decoded with the Kr for generating the hashed value h and the key recovery conditions RC, and the key recovery conditions RC are outputted depending on the propriety of the hash value h.


Inventors:
MIYAUCHI HIROSHI
SAKO KAZUE
YAMAZAKI MASASHI
DOMYO SEIICHI
TSUCHIYA HIROYOSHI
SUGANO KIYOKO
MORITA ICHIRO
TORII NAOYA
ANDO HIROYUKI
KURODA YASUTSUGU
Application Number:
JP1997000181593
Publication Date:
January 29, 1999
Filing Date:
July 07, 1997
Export Citation:
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Assignee:
NEC CORP
HITACHI LTD
FUJITSU LTD
International Classes:
G09C1/00; H04L9/08; (IPC1-7): H04L9/08
Domestic Patent References:
JPS5260492A1977-05-18
JPS61168405A1986-07-30
Attorney, Agent or Firm:
山川 政樹



 
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