Paper 2022/1139
Formal Security Definition of Metadata-Private Messaging
, Anysphere, Inc., Anysphere, Inc., Anysphere, Inc.Abstract
We present a novel, complete definition of metadata-private messaging (MPM) and show that our definition is achievable and non-trivially more general than previous attempts that we are aware of. Our main contributions are: 1) We describe a vulnerability in existing MPM implementations through a variation of the compromised-friend (CF) attack proposed by Angel et al. Our attack can compromise the exact metadata of any conversations between honest users. 2) We present a security definition for MPM systems assuming that some friends may be compromised. 3) We present a protocol satisfying our security definition based on Anysphere, an MPM system we deployed in practice.
Metadata
- Available format(s)
-
PDF
- Category
- Cryptographic protocols
- Publication info
- Preprint.
- Keywords
- private information retrieval metadata-private messaging security proof
- Contact author(s)
-
stzh1555 @ anysphere co
arvid @ anysphere co
sualeh @ anysphere co - History
- 2022-09-05: approved
- 2022-08-31: received
- See all versions
- Short URL
- https://ia.cr/2022/1139
- License
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CC BY
BibTeX
@misc{cryptoeprint:2022/1139,
author = {Shengtong Zhang and Arvid Lunnemark and Sualeh Asif},
title = {Formal Security Definition of Metadata-Private Messaging},
howpublished = {Cryptology {ePrint} Archive, Paper 2022/1139},
year = {2022},
url = {https://eprint.iacr.org/2022/1139}
}
