| 講演抄録／キーワード |
| 講演名 |
2006-07-21 14:15
Password-Authenticated Key Exchange for Multi-Party with Different Passwords Using a Constant Number of Rounds
○Jeong Ok Kwon（Korea Univ./Kyushu Univ.）・Kouichi Sakurai（Kyushu Univ.）・Dong Hoon Lee（Korea Univ.） |
| 抄録 |
（和） |
Password-authenticated key exchange (PAKE) for multi-party with different passwords
allows group users with different passwords to agree on a common session key by the help of a trusted server using their passwords only. In this setting, the users do not share a password between themselves but only with the server. The fundamental security goal of PAKE is security against dictionary attacks. In this paper, we present two in symmetric model and two in asymmetric model provably-secure protocols for this problem in the standard model under the DDH assumption; our first protocol in symmetric model is designed to provide forward secrecy and to secure against known-key attacks. The second protocol in symmetric model is designed to additionally provide key secrecy against the server. Our first protocol in asymmetric model is designed to provide forward secrecy and to secure against known-key attacks and server compromise attacks. The second protocol in asymmetric model is designed to additionally provide key secrecy against the server. Our all protocols require a constant number of rounds. Toward this goal, we recall some of the existing security notions for server-aided PAKE protocols in symmetric model and provide a formal definition of security for asymmetric model. To the best of our contribution, the new protocols are the first constant-round PAKE protocols for multi-party with different passwords along with a rigorous proof of security in the standard model per protocol. |
| （英） |
Password-authenticated key exchange (PAKE) for multi-party with different passwords
allows group users with different passwords to agree on a common session key by the help of a trusted server using their passwords only. In this setting, the users do not share a password between themselves but only with the server. The fundamental security goal of PAKE is security against dictionary attacks. In this paper, we present two in symmetric model and two in asymmetric model provably-secure protocols for this problem in the standard model under the DDH assumption; our first protocol in symmetric model is designed to provide forward secrecy and to secure against known-key attacks. The second protocol in symmetric model is designed to additionally provide key secrecy against the server. Our first protocol in asymmetric model is designed to provide forward secrecy and to secure against known-key attacks and server compromise attacks. The second protocol in asymmetric model is designed to additionally provide key secrecy against the server. Our all protocols require a constant number of rounds. Toward this goal, we recall some of the existing security notions for server-aided PAKE protocols in symmetric model and provide a formal definition of security for asymmetric model. To the best of our contribution, the new protocols are the first constant-round PAKE protocols for multi-party with different passwords along with a rigorous proof of security in the standard model per protocol. |
| キーワード |
（和） |
Cryptography / provable security, / group key exchange / password-authenticated key exchange / dictionary attack / round complexity / / |
| （英） |
Cryptography / provable security, / group key exchange / password-authenticated key exchange / dictionary attack / round complexity / / |
| 文献情報 |
信学技報, vol. 106, no. 176, ISEC2006-55, pp. 115-122, 2006年7月. |
| 資料番号 |
ISEC2006-55 |
| 発行日 |
2006-07-14 (ISEC) |
| ISSN |
Print edition: ISSN 0913-5685 |
| PDFダウンロード |
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