Can homomorphic property of a commitment scheme be harmful?

user1035648

6/9/24, 2:25 PM

Homomorphic properties turn out to be very useful, e.g., for achieving secure multiparty computation.
As a concrete example, homomorphic commitments can be used as a building block for secure election schemes: very roughly, during the voting stage, voters put their votes into homomorphic commitments, and during the tallying stage, the votes are counted in a verifiable manner by taking the product of all commitments.
The Question: Can homomorphic property of a commitment scheme be somehow harmful?

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multiparty-computation

commitments

Sacha Servan-Schreiber

6/9/24, 4:17 PM

Can you elaborate on what you mean by "harmful"? Do you mean insecure in some applications/settings? There is work on non-malleable commitments (e.g., https://dl.acm.org/doi/pdf/10.1145/276698.276722 + followup) so you might want to look into what attacks/motivations they have for defining non-malleability. For example, I think in some protocols, a homomorphic commitment scheme could be susceptible to man-in-the-middle attacks. Again, it's very application dependent...

user1035648

6/9/24, 11:01 PM

Non-malleable commitment with respect to opening or commitment may relate to harmful effect of homomorphic property of a commitment scheme. About man-in-the-middle attack: such attacks may be stopped by using an authenticated channel between the receiver and the sender. I think the sender may be dishonest.

Elon Musk

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EN: Can homomorphic property of a commitment scheme be harmful?

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