Abstract
We present Lightweight Email Signatures (LES), a simple cryptographic architecture for authenticating email. LES is an extension of DKIM, the recent IETF effort to standardize domain-based email signatures. LES shares DKIM’s ease of deployment: they both use the DNS to distribute a single public key for each domain. Importantly, LES supports common uses of email that DKIM jeopardizes: multiple email personalities, firewalled ISPs, incoming-only email forwarding services, and other common uses that often require sending email via a third-party SMTP server. In addition, LES does not require DKIM’s implied intra-domain mechanism for authenticating users when they send email.
LES provides these features using identity-based signatures. Each domain authority generates a master keypair, publishes the public component in the DNS, and stores the private component securely. Using this private component, the authority delivers to each of its users, via email, an individual secret key whose identity string corresponds to the user’s email address. A sender then signs messages using this individual secret key. A recipient verifies such a signature by querying the appropriate master public key from the DNS, computing the sender’s public key, and verifying the signature accordingly. As an added bonus, the widespread availability of user-level public keys enables deniable authentication, such as ring signatures. Thus, LES provides email authentication with optional repudiability.
We built a LES prototype to determine its practicality. Basic user tests show that the system is relatively easy to use, and that cryptographic performance, even when using deniable authentication, is well within acceptable range.
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References
Adida, B., Hohenberger, S., Rivest, R.L.: Ad-hoc-group signatures from hijacked keypairs (2005), http://theory.lcs.mit.edu/~rivest/publications
American Banking Association. Beware of Internet Scrooges this Holiday, http://biz.yahoo.com/prnews/041209/dcth013_1.html
Anti-Phishing Working Group, http://www.antiphishing.org/
Anti-Phishing Working Group. Digital Signatures to Fight Phishing Attacks, http://www.antiphishing.org/smim-dig-sig.htm
Bellare, M., Namprempre, C., Neven, G.: Security proofs for identity-based identification and signature schemes. In: Stern, J. (ed.) EUROCRYPT 1999. LNCS, vol. 1592, pp. 268–286. Springer, Heidelberg (1999)
Bellovin, S.M.: Spamming, phishing, authentication, and privacy. Inside Risks, Communications of the ACM 47(12) (December 2004)
Borisov, N., Goldberg, I., Brewer, E.: Off-the-record communication, or, why not to use PGP. In: WPES 2004, pp. 77–84. ACM Press, New York (2004)
Brown, D.R.: Deniable authentication with rsa and multicasting. In Cryptology ePrint Archive, Report 2005/056 (2005)
Cramer, R., Damgård, I.B., Schoenmakers, B.: Proof of partial knowledge and simplified design of witness hiding protocols. In: Desmedt, Y.G. (ed.) CRYPTO 1994. LNCS, vol. 839, pp. 174–187. Springer, Heidelberg (1994)
Crispin, M.: RFC 1730: Internet Mail Access Protocol - Version (December 4, 1994)
Dhamija, R., Tygar, J.D.: Phish and hIPs: Human interactive proofs to detect phishing attacks. In: Baird, H.S., Lopresti, D.P. (eds.) HIP 2005. LNCS, vol. 3517, pp. 127–141. Springer, Heidelberg (2005)
Damiani, E., et al.: Spam Attacks: P2P to the Rescue. In: WWW 2004, pp. 358–359 (2004)
M.C., et al.: Internet X.509 Public Key Infrastructure (latest draft). IETF Internet Drafts (January 2005)
Garfinkel, S.L.: Email-Based Identification and Authentication: An Alternative to PKI? IEEE Security & Privacy 1(6), 20–26 (2003)
Guillou, L.C., Quisquater, J.-J.: A “Paradoxical” identity-based signature scheme resulting from zero-knowledge. In: Goldwasser, S. (ed.) CRYPTO 1988. LNCS, vol. 403, pp. 216–231. Springer, Heidelberg (1990)
Herzberg, A.: Controlling spam by secure internet content selection. In: Blundo, C., Cimato, S. (eds.) SCN 2004. LNCS, vol. 3352, pp. 337–350. Springer, Heidelberg (2005)
Hoffman, P.: SMTP Service Exten. for Secure SMTP over Transport Layer Security. Internet Mail Consortium RFC, http://www.faqs.org/rfcs/rfc3207.html
IETF: The DKIM Working Group, http://mipassoc.org/dkim/
IETF. MTA Authorization Records in DNS (MARID) (June 2004), http://www.ietf.org/html.charters/OLD/marid-charter.html
Jakobsson, M.: Modeling and Preventing Phishing Attacks. In: S. Patrick, A., Yung, M. (eds.) FC 2005. LNCS, vol. 3570, p. 89. Springer, Heidelberg (2005)
Jakobsson, M., Sako, K., Impagliazzo, R.: Designated verifier proofs and their applications. In: EUROCRYPT 1996. LNCS, vol. 1233. Springer, Heidelberg (1996)
Krawczyk, H., Rabin, T.: Chameleon signatures. In: Network and Distributed System Security (NDSS) (2000)
Levine, J., DeKok, A., et al.: Lightweight MTA Authentication Protocol (LMAP) Discussion and Comparison (February 2004), http://www.taugh.com/draft-irtf-asrg-lmap-discussion-01.txt
Levine, J.R.: A Flexible Method to Validate SMTP Senders in DNS (2004), http://www1.ietf.org/proceedings_new/04nov/IDs/draft-levine-fsv-01.txt
MAPS. RBL - Realtime Blackhole List (1996), http://www.mail-abuse.com/services/mds_rbl.html
Mason, J.: Filtering Spam with SpamAssassin. In: HEANet Conference (2002)
MessageLabs. Annual Email Security Report (December 2004), http://www.messagelabs.com/intelligence/2004report
Meyer, T., Whateley, B.: SpamBayes: Effective open-source, Bayesian based, email classification system. In: Conference on Email and Anti-Spam (July 2004)
Microsoft. Phishing Scams: 5 Ways to Help Protect Your Identity, http://www.microsoft.com/athome/security/email/phishing.mspx
Microsoft. The Sender ID Framework, http://www.microsoft.com/mscorp/safety/technologies/senderid/default.ms.px
Myers, J.: RFC 1939: Post Office Protocol - Version 3 (May 1996)
News, Z.: http://news.zdnet.com/2100-9595_22-519795.html?legacy=zdnn
Rivest, R.L., Shamir, A., Tauman, Y.: How to leak a secret. In: Boyd, C. (ed.) ASIACRYPT 2001. LNCS, vol. 2248, pp. 552–565. Springer, Heidelberg (2001)
Sahami, M., Dumais, S., Heckerman, D., Horvitz, E.: A Bayesian Approach to Filtering Junk E-Mail. In: Learning for Text Categorization (May 1998)
Schneier, B.: Safe Personal Computing. Schneier On Security Weblog (December 2004), http://www.schneier.com/blog/archives/2004/12/safe_personal_c.html
Shamir, A.: Identity-based cryptosystems and signature schemes. In: Blakely, G.R., Chaum, D. (eds.) CRYPTO 1984. LNCS, vol. 196, pp. 47–53. Springer, Heidelberg (1985)
Smetters, D., Durfee, G.: Domain-based administration of identity-based cryptosystems for secure email and IPSEC. In: USENIX Security Symposium (2003)
The Spamhaus Project. The Spamhaus Block List, http://www.spamhaus.org/sbl/
Tumbleweed Communications. Digitally-Signed Emails to Protect Against Phishing Attacks, http://www.tumbleweed.com/solutions/finance/antiphishing.html
Zimmerman, P.: Pretty Good Privacy, http://www.pgp.com
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Adida, B., Chau, D., Hohenberger, S., Rivest, R.L. (2006). Lightweight Email Signatures (Extended Abstract). In: De Prisco, R., Yung, M. (eds) Security and Cryptography for Networks. SCN 2006. Lecture Notes in Computer Science, vol 4116. Springer, Berlin, Heidelberg. https://doi.org/10.1007/11832072_20
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