尾花 賢 
オバナ サトシ 
OBANA Satoshi 


東京工業大学  理工学研究科  電気・電子工学専攻  博士  1998/03/31  修了  日本 

博士(工学)  東京工業大学  1998/03/31 


研究論文(学術雑誌)  共著  Verifiably Multiplicative Secret Sharing  Maki Yoshida, Satoshi Obana  IEEE Trans. Information Theory  65/ 5  2019 
研究論文(学術雑誌)  共著  Combinatorial Bounds on Authentication Codes with Arbitration  Kaoru Kurosawa  Designs, Codes and Cryptography  2001/01/01 
研究論文(学術雑誌)  共著  Bounds and Combinatorial Structure of Multi-Receiver Authentication Codes  Kaoru Kurosawa  Designs, Codes and Cryptography  2001/01/01 
研究論文(学術雑誌)  単著  Combinatorial Classification of Optimal Authentication Codes with Arbitration  Kaoru Kurosawa  Designs, Codes and Cryptography  2000/07/01 

口頭発表(一般)  Protocols for Evaluating Conditional Sum on Encrypted Data  ISITA 2014  2014/10/26 
口頭発表(一般)  Cheating Detectable Secret Sharing Schemes Supporting an Arbitrary Finite Field  IWSEC 2014  2014/08/28  In this paper, we present k-out-of-n threshold secret sharing scheme which can detect share forgery by at most k-1 cheaters. Though efficient schemes with such a property are presented so far, some schemes cannot be applied when a secret is an element of F_{2^N} and some schemes require a secret to be an element of a multiplicative group. The schemes proposed in the paper possess such a merit that a secret can be an element of arbitrary finite field. The sizes of share of proposed schemes are only 2 and 3 bits longer than the existing lower bound, respectively. 
口頭発表(一般)  New Security Definitions for Biometric Authentication with Template Protection: Toward covering more threats against authentication systems  2013 BIOSIG - International Conference of Biometrics Special Interest Group  2013/09/04 
口頭発表(一般)  Almost Optimum t-Cheater Identifiable Secret Sharing Schemes  Eurocrypt 2011  2011/05/15  In Crypto’95, Kurosawa, Obana and Ogata proposed a k-out-of-n secret sharing scheme capable of identifying up to t cheaters with probability 1−epsilon under the condition t<=(k–1)/3. The size of share of the scheme satisfies Vi=|S|^{t+2}, which was the most efficient scheme known so far. In this paper, we propose new k-out-of-n secret sharing schemes capable of identifying cheaters. The proposed scheme possesses the same security parameters t, epsilon as those of Kurosawa et al.. The scheme is surprisingly simple and its size of share is Vi=|S|/epsilon, which is much smaller than that of Kurosawa et al. and is almost optimum with respect to the size of share; that is, the size of share is only one bit longer than the existing bound. Further, this is the first scheme which can identify cheaters, and whose size of share is independent of any of n, k and t. We also present efficient schemes which can identify up to (k−2)/2, and (k−1)/2 cheaters. 
口頭発表(一般)  Almost Optimum Secret Sharing Schemes Secure Against Cheating for Arbitrary Secret Distribution  Asiacrypt 2006  2006/12/06