Anamorphic Encryption Covert Channels

[TheWanderer1983]

Hello all,

Abstract:
Cryptosystems have been developed over the years under the typical prevalent setting which assumes
that the receiver’s key is kept secure from the adversary, and that the choice of the message to be sent is
freely performed by the sender and is kept secure from the adversary as well. Under these fundamental
and basic operational assumptions, modern Cryptography has flourished over the last half a century
or so, with amazing achievements: New systems (including public-key Cryptography), beautiful and
useful models (including security definitions such as semantic security), and new primitives (such as
zero-knowledge proofs) have been developed. Furthermore, these fundamental achievements have been
translated into actual working systems, and span many of the daily human activities over the Internet.
However, in recent years, there is an overgrowing pressure from many governments to allow the
government itself access to keys and messages of encryption systems (under various names: escrow en-
cryption, emergency access, communication decency acts, etc.). Numerous non-direct arguments against
such policies have been raised, such as “the bad guys can utilize other encryption system” so all other
cryptosystems have to be declared illegal, or that “allowing the government access is an ill-advised pol-
icy since it creates a natural weak systems security point, which may attract others (to masquerade as
the government).” It has remained a fundamental open issue, though, to show directly that the above
mentioned efforts by a government (called here “a dictator” for brevity) which mandate breaking of the
basic operational assumption (and disallowing other cryptosystems), is, in fact, a futile exercise. This is
a direct technical point which needs to be made and has not been made to date.
In this work, as a technical demonstration of the futility of the dictator’s demands, we invent the
notion of “Anamorphic Encryption” which shows that even if the dictator gets the keys and the messages
used in the system (before anything is sent) and no other system is allowed, there is a covert way
within the context of well established public-key cryptosystems for an entity to immediately (with
no latency) send piggybacked secure messages which are, in spite of the stringent dictator conditions,
hidden from the dictator itself! We feel that this may be an important direct technical argument against
the nature of governments’ attempts to police the use of strong cryptographic systems, and we hope to
stimulate further works in this direction.

LINK TO PAPER: https://eprint.iacr.org/2022/639.pdf
IACR PRESENTATION VIDEO: https://www.youtube.com/watch?v=a8q-zznrgFM
FURTHER RESEARCH: Anamorphic Encryption, Revisited
Anamorphic Encryption: New Constructions and Homomorphic Realizations
The Self-Anti-Censorship Nature of Encryption: On the Prevalence of Anamorphic Cryptography

[wkrp]

For "The Self-Anti-Censorship Nature of Encryption", there is also a PETS 2023 paper and conference presentation by Giuseppe Persiano.

https://petsymposium.org/popets/2023/popets-2023-0104.php
https://www.youtube.com/watch?v=8HwLPQOLFrc