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mit-dci / opencbdc-tx

A transaction processor for a hypothetical, general-purpose, central bank digital currency
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Exploring Blind Signatures for Privacy Approach #49

Open temucin opened 2 years ago

temucin commented 2 years ago

Question

It would be useful to explore the usage of blind signatures as a means of adding a privacy element to the system. As articulated by David Chaum, here, and then later implemented in DigiCash and GNU Taler, and most recently presented as a hypothetical CBDC implementation with the Swiss National Bank.

At the surface, it seems a simpel alternative over zero-knowledge proofs, shoudl fit the current proposed architecture, and lend itself to be quite usable in many network models.

Benefit

Blind signatures are a relatively straightforward usage of cryptographic signatures to add privacy. There is a history of usage and previous solutions to lend knowledge and expertise for implementations (Digicash, GNU Taler). Finally, the original usage of blind signatures for privacy in digital currency seems a good fit for the existing centrally operated architecture.

Proposed Solution

So far, this proposal has only identified a potential fit for the blind signature scheme. Next-step work would require a deeper analysis of previous blind signature implementations, integration with the existing codebase, and finally develop an initial understanding of the trade-offs and benefits versus other design choices.

Possible Difficulties

The usage of a UXTO model like UHS was not present in the previously mentioned implementations.

Prior Work

Original description of blind signature proposal, https://sceweb.sce.uhcl.edu/yang/teaching/csci5234WebSecurityFall2011/Chaum-blind-signatures.PDF

Open-source implementation of blind-signature wallet system, https://taler.net/en/index.html

SNB and David Chaum CBDC paper, https://www.snb.ch/en/mmr/papers/id/working_paper_2021_03

Code of Conduct

HalosGhost commented 2 years ago

This looks like a great proposal to walk through. Are you available to present this proposal at our first WG1 meeting (on Wednesday)?

temucin commented 2 years ago

This looks like a great proposal to walk through. Are you available to present this proposal at our first WG1 meeting (on Wednesday)?

Would be happy to do so.