標的型攻撃メール対策を目的とした送信者認証の提案

全文

(1)1,a). 2. 1,2. ID IC. 1. •. [1]. ID. IC. URL. 2. S/MIME(Secure/Multipurpose Internet Mail Extensions)[2]. PGP(Pretty Good Pri-. vacy)[3]. •. [4] CA(Certificate Authority,. • •. URL [5]. 1. 3-7-2 2. a). 3-7-2 [email protected]. ).

(2) Alice. Sender ID. Bob. SPF(Sender Policy Framework). 秘密通信. DomainKeys DKIM(DomainKeys Identified Mail) IP. 𝐶. 送信者. = 𝑟 × 𝐼𝐶 × 𝐸𝑚𝑎𝑖𝑙 × 𝑃. Alice. 1. 鍵 𝐶. 1. Alice. Bob 𝐴 ⊕ 𝐻(𝑒̂ 𝐶. 3.. =𝑆. 通信. •. 𝑆 = 𝐻(𝐼𝐶 × 𝐸𝑚𝑎𝑖𝑙) 𝐸 = 𝐻(𝑒̂ 𝑃, 𝐼𝐶 × 𝐸𝑚𝑎𝑖𝑙 × 𝑄 ) 𝐴 =𝑆⊕𝐸. • S/MIME. PGP. , 𝐸𝑚𝑎𝑖𝑙 × 𝑄. 送信者 Alice. 鍵 𝐶. 2. 認証値. 認証回数. S. 0. 2. • • • •. 3.2.1. •. PKG (G1 , G2 , GT ). •. 3.1 IC IC. ID Suica. (IBE)[6]. IC. P ∈ G1 , Q ∈ G2. • • •. IC IC. IC. eˆ(•, •) : G1 × G2 → GT. H Alice. Email. ID(IC. IC). Bob r(∈ Z/pZ). (Email) p. ID. 3.2.2. 1. 1 ice ID. 1 PKG. AlP. r × IC × Email × P. . Ckey = Bob. ckey. Android [7] IC. NFC Android. IC. IC. 3.2.3. 2. 2. 2. Alice. 2 3.2 Alice. Bob. PKG PKG. ( 1 ) S = H(IC × Email). ( 2 ) E = H(ˆ e(P, IC × Email × Q)r ) ! A=S E. Bob.

(3) S Bob. 4.. A. Android. !. H(ˆ e(Ckey , Email × Q)) ! = H(IC × Email) H(ˆ e (P, IC × Email × ! r Q) ) H(ˆ e (r × IC × P × Email, Q)) ! = H(IC × Email) H(ˆ e (P, Q)IC×Email×r ) ! H(ˆ e (P, Q)IC×Email×r ) A. = H(IC × Email). IC. PBC. Java. =S. Bob (. S. Android. jPBC(Java Pairing-Based Cryptography) IC. Alice. 0). 3.2.4 Alice. S. A1 S1 = H(S). 5.. E = H(ˆ e (P, IC × Email × Q)r ) ! A1 = S1 E. 5.1 (1) S/MIME. S2 = H( H(S), S3 = H( H( H(S))), .... PGP. S E. 3. A Alice. 4. S/MIME. 4. Bob. ID (2). 3.2.5 Bob. P,. , 2. N = k×P. Ckey. !. H(ˆ e (Ckey , Email × Q)) ! = H(...H(IC × Email)...) H(ˆ e(P, IC × Email × ! r Q) ) H(ˆ e(r × IC × P × Email, Q)) ! = H(...H(IC × Email)...) ! H(ˆ e (P, Q)IC×Email×r ) H(ˆ e (P, Q)IC×Email×r ) An. = H(...H(IC × Email)...) = Sn. N. k. (3) IC. Alice. Bob. 認証情報を付加. Alice. k. Aliceであるか認証. S. Sn′ Sn′ = H(H(...H(S)...)). メール送信. Sn = Sn′ 1 3.

(4) Bob. Alice. 6.. 証明書秘密鍵. ID. 証明書秘密鍵受信者の公開鍵で暗号化. 暗号メール. 平文メール. IC. 受信者の秘密鍵で複合化. 署名メール. 署名メール. PGP. 平文メール. 暗号メール. 送信者の秘密鍵で署名作成. S/MIME. 署名確認送信者の証明書で署名を検証. 4. [1]. IC. Ckey [2]. 1 2 [3]. 5.2 •. [4]. IC. [5] [6]. •. Ckey [7]. •. S nexus7. SHA256 1. 1. CPU CPU. 1 1 1.56ms. SHA256 10 13.46ms. 100 140.96ms. 1000 1349.73ms. IPA :. IPA. , http://www.ipa.go.jp/about/ technicalwatch/20111003.html ,2011 B Ramsdell, Brute Squad Labs, S Turner : S/ MIME Version 3 2 Message Specification , RFC5751, 2010 J Callas, PGP Corporation, L. Donnerhacke : OPEN PGP Message Format ,RFC4880, 2007 : ,http://www.netagent.co.jp/product/sakimori/ ,2012 , , : , No.16 p100-110, 2012 CRYPTREC : ID ,http:/ /www.cryptrec.go.jp/report/c08 idb2008.pdf ,2008 W. Diﬃe, M. E. Hellman : ”New Directions in Cryptography”, IEEE Transactions on Information Theory, vol.IT-22, No.6, pp.644-654, 1976..

(5)