What does the bounded storage model mean?

user77340

3/9/23, 9:17 AM

In the bounded storage model, it assumes the storage of the adversary is bounded or limited, and thus it is possible that we can achieve a kind of cryptography without relying on hardness assumption. But what does it mean by "bounded storage"? Should it assume the length of the message is always too long for any computer on the earth to store? So can I conclude that the cryptographic scheme that replies on bounded storage model is not so efficient(if it is not very inefficient)? Since it should always send a very long message. And I think it is not compatible with blockchain(hard to imagine a very long message is stored on the blockchain). Am I right?

Reference: Simple Schemes in the Bounded Storage Model, Disappearing Cryptography in the Bounded Storage Model, Secure Multiparty Computation in the Bounded Storage Model, Speak Much, Remember Little: Cryptography in the Bounded Storage Model, Revisited

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security-definition

adversarial-model

fgrieu

3/9/23, 9:37 AM

[edited] My very limited understanding of the bounded storage model is that it assumes adversaries have limited storage _for their intermediary calculations_, but lets normal users use feasibly little storage, and _aims_ (if not necessarily succeeds) to work with as normal/small size of messages as possible.

Ievgeni

3/9/23, 1:55 PM

Can you add sources/link where this expression appear to help us to understand the context?

fgrieu

3/9/23, 3:17 PM

@levgeni: about the only paper on the BSM that I attempted to read is Jiaxin Guan, Mark Zhandary: [_Simple Schemes in the Bounded Storage Model_](https://eprint.iacr.org/2019/507.pdf), in [proceedings of Eurocrypt 2019](https://doi.org/10.1007/978-3-030-17659-4_17).