Abstract
We explore how to build a blind certificate authority (CA). Unlike conventional CAs, which learn the exact identity of those registering a public key, a blind CA can simultaneously validate an identity and provide a certificate binding a public key to it, without ever learning the identity. Blind CAs would therefore allow bootstrapping truly anonymous systems in which no party ever learns who participates. In this work we focus on constructing blind CAs that can bind an email address to a public key. To do so, we first introduce secure channel injection (SCI) protocols. These allow one party (in our setting, the blind CA) to insert a private message into another party's encrypted communications. We construct an efficient SCI protocol for communications delivered over TLS, and use it to realize anonymous proofs of account ownership for SMTP servers. Combined with a zero-knowledge certificate signing protocol, we build the first blind CA that allows Alice to obtain a X.509 certificate binding her email address [email protected] to a public key of her choosing without ever revealing ''alice'' to the CA. We show experimentally that our system works with standard email server implementations as well as Gmail.
Original language | English |
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Title of host publication | Proceedings - 2019 IEEE Symposium on Security and Privacy, SP 2019 |
Publisher | Institute of Electrical and Electronics Engineers Inc. |
Pages | 1015-1032 |
Number of pages | 18 |
ISBN (Electronic) | 9781538666609 |
DOIs | |
State | Published - May 2019 |
Externally published | Yes |
Event | 40th IEEE Symposium on Security and Privacy, SP 2019 - San Francisco, United States Duration: 19 May 2019 → 23 May 2019 |
Publication series
Name | Proceedings - IEEE Symposium on Security and Privacy |
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Volume | 2019-May |
ISSN (Print) | 1081-6011 |
Conference
Conference | 40th IEEE Symposium on Security and Privacy, SP 2019 |
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Country/Territory | United States |
City | San Francisco |
Period | 19/05/19 → 23/05/19 |
Bibliographical note
Publisher Copyright:© 2019 IEEE.
Funding
This work was partially supported by a Junior Fellow award from the Simons Foundation, NSF grants CNS-1330308, CNS-1558500, CNS-1704527, TWC-1646671, TWC-1664445, CNS-1561209, CNS-1217821, CNS-1704788, AFOSR Award FA9550-15-1-0262, a Microsoft Faculty Fellowship, a Google Faculty Research Award, and a gift from Microsoft.
Funders | Funder number |
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National Science Foundation | 1704788 |
Air Force Office of Scientific Research | FA9550-15-1-0262 |
Simons Foundation | |
National Sleep Foundation | CNS-1704788, CNS-1704527, TWC-1664445, CNS-1561209, TWC-1646671, CNS-1330308, CNS-1217821, CNS-1558500 |
Microsoft | |
Keywords
- Anonymity
- MPC
- Privacy
- Secure-Multiparty-Computation
- TLS
- Zero-knowledge-Proof