Equivocating Yao

Canetti, Ran; Poburinnaya, Oxana; Venkitasubramaniam, Muthuramakrishnan

doi:10.1145/3055399.3055495

Cited by 14 publications

(2 citation statements)

References 23 publications

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“…This notion has received considerable attention in the literature, see e.g. [14,16,27,29]. In contrast to adaptive security where an adversary may learn all secrets of a corrupted party, we achieve that remotely hacking a party after it received its first input does not impact the confidentiality and integrity of a party's inputs and outputs, unless all parties have been corrupted.…”

Section: Related Workmentioning

confidence: 96%

Fortified Multi-Party Computation: Taking Advantage of Simple Secure Hardware Modules

Broadnax¹,

Koch

Mechler

et al. 2021

Proceedings on Privacy Enhancing Technologies

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In practice, there are numerous settings where mutually distrusting parties need to perform distributed computations on their private inputs. For instance, participants in a first-price sealed-bid online auction do not want their bids to be disclosed. This problem can be addressed using secure multi-party computation (MPC), where parties can evaluate a publicly known function on their private inputs by executing a specific protocol that only reveals the correct output, but nothing else about the private inputs. Such distributed computations performed over the Internet are susceptible to remote hacks that may take place during the computation. As a consequence, sensitive data such as private bids may leak. All existing MPC protocols do not provide any protection against the consequences of such remote hacks. We present the first MPC protocols that protect the remotely hacked parties’ inputs and outputs from leaking. More specifically, unless the remote hack takes place before the party received its input or all parties are corrupted, a hacker is unable to learn the parties’ inputs and outputs, and is also unable to modify them. We achieve these strong (privacy) guarantees by utilizing the fact that in practice parties may not be susceptible to remote attacks at every point in time, but only while they are online, i.e. able to receive messages. To this end, we model communication via explicit channels. In particular, we introduce channels with an airgap switch (disconnect-able by the party in control of the switch), and unidirectional data diodes. These channels and their isolation properties, together with very few, similarly simple and plausibly remotely unhackable hardware modules serve as the main ingredient for attaining such strong security guarantees. In order to formalize these strong guarantees, we propose the UC with Fortified Security (UC#) framework, a variant of the Universal Composability (UC) framework.

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Section: Related Workmentioning

confidence: 96%

Fortified Multi-Party Computation: Taking Advantage of Simple Secure Hardware Modules

Broadnax¹,

Koch

Mechler

et al. 2021

Proceedings on Privacy Enhancing Technologies

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“…In somewhere equivocal (non-committing) encryption [HJO + 16] it is possible to modify a few blocks of the encrypted data. Perhaps the closest concept to our work is the notion of functionally equivocal (non-committing) encryption from the recent work of Canetti, Poburinnaya and Venkitasubramaniam [CPV16]. In that work, it's possible to open a simulated encryption to any message m 0 = f (x) which is in the range of some function f , where f can be an expanding function and the secret key size is only proportional to |x| rather than to |m 0 |.…”

Section: Related Workmentioning

confidence: 99%

The Edited Truth

Goldwasser

Klein

Wichs

2017

Theory of Cryptography

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We introduce two new cryptographic notions in the realm of public and symmetric key encryption.• Encryption with invisible edits is an encryption scheme with two tiers of users: "privileged" and "unprivileged". Privileged users know a key pair (pk, sk) and "unprivileged" users know a key pair (pk e , ske) which is associated with an underlying edit e to be applied to messages encrypted. Each key pair on its own works exactly as in standard public-key encryption, but when an unprivileged user attempts to decrypt a ciphertext generated by a privileged user of an underlying plaintext m, it will be decrypted to an edited m 0 = Edit(m, e). Here, Edit is some supported edit function and e is a description of the particular edit to be applied. For example, we might want the edit to overwrite several sensitive blocks of data, replace all occurrences of one word with a di↵erent word, airbrush an encrypted image, etc. A user shouldn't be able to tell whether he's an unprivileged or a privileged user.

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