CryptoDB
Francesco Migliaro
Publications
Year
Venue
Title
2024
EUROCRYPT
Anamorphic Encryption: New Constructions and Homomorphic Realizations
Abstract
The elegant paradigm of Anamorphic Encryption (Persiano
et al., Eurocrypt 2022) considers the question of establishing a private
communication in a world controlled by a dictator. The challenge is to
allow two users, sharing some secret anamorphic key, to exchange covert
messages without the dictator noticing, even when the latter has full
access to the regular secret keys. Over the last year several works con-
sidered this question and proposed constructions, novel extensions and
strengthened definitions.
In this work we make progress on the study of this primitive in three
main directions. First, we show that two general and well established
encryption paradigms, namely hybrid encryption and the IBE-to-CCA
transform, admit very simple and natural anamorphic extensions. Next,
we show that anamorphism, far from being a phenomenon isolated to
"basic" encryption schemes, extends also to homomorphic encryption.
We show that some existing homomorphic schemes, (and most notably
the fully homomorphic one by Gentry, Sahai and Waters) can be made
anamorphic, while retaining their homomorphic properties both with
respect to the regular and the covert message.
Finally we refine the notion of anamorphic encryption by envisioning the
possibility of splitting the anamorphic key into an encryption component
(that only allows to encrypt covert messages) and a decryption compo-
nent. This makes possible for a receiver to set up several, independent,
covert channels associated with a single covert key.
Coauthors
- Dario Catalano (1)
- Emanuele Giunta (1)