CPS-???? | Canonical CBOR Serialization Standard

[HinsonSIDAN]

This CPS emerged from community feedback at events like Cardano Builder Fest 2025, where developers identified CBOR serialization fragmentation as a critical pain point hindering ecosystem maturity.

This CPS addresses the growing interoperability challenges caused by non-deterministic CBOR serialization across Cardano's tooling ecosystem. The same logical transaction or script can be encoded in multiple valid ways, leading to different hashes and breaking multi-signature workflows, cross-tool transaction building, and script reference consistency.

Ideally we can establish a canonical CBOR serialization standard that would be adopted across major libraries and wallets, ensuring predictable behavior and reducing the development friction that currently exists when working across different tools.

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[fallen-icarus]

Thanks for opening this discussion! This topic is outside my area, but I came across this comment (and this one) by @dcoutts a while ago which AFAIU explains the reasoning at the time. The entire Issue thread might be worth a read.

[GeorgeFlerovsky]

FYI @nau @fernweh0

[yHSJ]

Thank you for drafting a CPS about this. You're right, a lack of canonical encoding has definitely been frustrating for many of us Cardano developers, especially those of us working on alternative node implementations (I can speak to my experience working on Amaru primarily). I have only done a quick skim of the content so I won't comment on the particulars in the CPS here right now, but hopefully I will have more time later to sit down and reread it carefully.

But, to give some context:
At the first node diversity workshop, canonical representation of ledger state was heavily discussed since it's needed (or at least very helpful) for many things, including testing and bootstrapping.

Sundae Labs has started work on a conformance testing suite which currently uses the NewEpochState, encoded as CBOR, from the Haskell node but we're eager to conform with a reasonable and appropriate standard there. They currently live in the Cardano Blueprints project, where I assume a canonical ledger state specification would eventually reside, along with a CIP: https://github.com/cardano-scaling/cardano-blueprint/tree/main/src/ledger/conformance-test-vectors (cc: @Quantumplation)

Tweag has received treasury funding to work on exactly that actually, and they have a draft PR open already: #1083 (cc: @nc6 and @qnikst)

[rphair]

@HinsonSIDAN it's not too early to decide on a single category that you think represents the ecosystem sector where the most work would need to be done to cover this problem statement.

If don't think that possible, or would like to promote the idea of multiple categories in CIPs and CPSs, you could read this recent comment:

• CIP-0112? | Observe script type #749 (comment)

and contribute your experience & professional opinion here, if you feel multiple categories would be better than single choices, and also if any other conservatively chosen additional tags could provide good coverage of what CIPs and CPSs are really about:

• Extended vocabulary for CIP/CPS classification and search cf-cip-frontend#55

[HinsonSIDAN]

I have chosen the Tools category for now. Thanks for reminding that

[rphair]

@HinsonSIDAN now that this is marked "Ready for Review" we'll add it as Triage which puts it on the agenda for our next CIP meeting (https://hackmd.io/@cip-editors/123).

In the meantime I think it'll be useful to get some co-review with this current CIP candidate (cc @qnikst @lehins @nc6 @Ryun1 @Crypto2099):

• #1083