Title:
RE-ENCRYPTION KEY GENERATION DEVICE, RE-ENCRYPTION DEVICE, ENCRYPTION DEVICE, DECRYPTION DEVICE AND PROGRAM
Document Type and Number:
WIPO Patent Application WO/2016/051591
Kind Code:
A1
Abstract:
A re-encryption key generation device of an embodiment of the present invention performs re-encryption without decrypting encrypted text data obtained with a first public key, and generates a re-encryption key for obtaining re-encrypted text data that can be decrypted with a second secret key. The re-encryption key generation device stores a first secret key corresponding to the first public key and a second re-encryption key generation key that is different from a second public key corresponding to the second secret key. The re-encryption key generation device generates the re-encryption key on the basis of the first secret key, the second re-encryption key generation key and a plurality of random numbers. The second re-encryption key generation key is formed from a plurality of system-specific values and the second secret key. The re-encryption key includes a power index having a numerator part and a denominator part, or a scalar having a numerator part and a denominator part. The numerator part has the form of a linear combination of the second secret key in which utilized are at least one from between the random numbers and a plurality of secret values that determine relationships between the system-specific values. The denominator part comprises the first secret key.
Inventors:
HAYASHI RYOTARO (JP)
MATSUSHITA TATSUYUKI (JP)
MATSUSHITA TATSUYUKI (JP)
Application Number:
PCT/JP2014/076562
Publication Date:
April 07, 2016
Filing Date:
October 03, 2014
Export Citation:
Assignee:
TOSHIBA KK (JP)
TOSHIBA SOLUTIONS CORP (JP)
TOSHIBA SOLUTIONS CORP (JP)
International Classes:
H04L9/08; H04L9/14
Domestic Patent References:
| WO2014024956A1 | 2014-02-13 |
Other References:
RYOTARO HAYASHI ET AL.: "Unforgeability of re- encryption keys against collusion attack in proxy re-encryption", IWSEC'11 PROCEEDINGS OF THE 6TH INTERNATIONAL CONFERENCE ON ADVANCES IN INFORMATION AND COMPUTER SECURITY, 2011, pages 210 - 229, XP019168391, DOI: doi:10.1007/978-3-642-25141-2_14
Attorney, Agent or Firm:
KURATA, Masatoshi et al. (JP)
Masatoshi Kurata (JP)
Masatoshi Kurata (JP)
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