I read about CertifiedData in the The Internet Computer Interface Specification :: Internet Computer The spec doesn’t talk about actual usage of this piece of info. I don’t see much in the doc either. Is there a recommended usage case / reference implementation somewhere? My takeaway is that Certi…

Yes, documentation and best practice is a bit scarce on this. We’ll have more eventually (also talks etc). You can see some existing applications of certified data: The Internet Identity canister uses Canister Signatures (also explained in the Interface Spec) using this code: https://github.com/d…

Can anyone speak to the motivation for providing a certified response? I understand that verifiability is good, but I’m trying to understand its relevance on a tamperproof platform. Is this a “trust but verify” mechanism? I’m interested in understanding more about why it’s optional and not always …

My guess is that: the Chain Key is tamperproof; The historical states are not stored (for scaling reasons) so we can’t verify all state changes from “genesis” natively. Outbound nodes are hosted by independent datacenters (afaik) – to maintain privacy on the data (compared to ethereum & co that al…

[image] paulyoung: Can anyone speak to the motivation for providing a certified response? As opposed to an uncertified one? Query calls are executed by a single replica. Our trust model for the IC is that some replicas may be compromised, but not many. So a query call may hit a malicious rep…

[image] nomeata: a query call may hit a malicious replica, and could fake any response to you. Certification protects against that. I think this is the key thing I was missing. I was thinking that if you couldn’t trust a replica to begin with you wouldn’t trust it telling you that a response …

Ah, right! A certificate is equivalent to a signature of the whole subnet. Not the single node certifies, but the subnet certifies, and the node just passes the certificate through.

@nomeata I probably can deduce this from the code myself, but in an effort to save myself some time, do you have an example of how to ‘prove’ the cert is valid using the MerkleTree class? I’m guessing in my query function I need to return CertifiedData.getCertificate and MerkleTree.reveal(myTree, …

Guess you miss one point. The key that signs the certificate doesn’t belong to the canister itself, it is a multi-part threshold key that collectively belongs to the subnet. No single replica/canister can get hold to it. However, subnet will blindly certify whatever data the canister provides. Your…

Hmmm…ok. So let’s talk about a real world technical implementation. @nomeata was proposing that the witness from his merkle tree class would work. So if I have that witness and it reveals the data, I’m guessing that the “top” of the witness is the root that is certified. I need to check that the cer…

dfinity/agent-js/blob/main/apps/sw-cert/src/sw/validation.ts import { Cbor as cbor, Certificate, HashTree, HttpAgent, lookupPathEx, reconstruct, } from '@dfinity/agent'; import { blobFromUint8Array, blobToUint8Array } from '@dfinity/candid'; import { Principal } from '@dfin…

Thanks @anon74414410 ! I’m guessing I can follow this for the general flow of what I want to do. Do you know of anyone that has implemented a comparable flow in Motoko?

Recommended usage of CertifiedData

Developers

nomeata September 15, 2021, 4:36pm 18

Also see Certified Assets from Motoko (PoC/Tutorial)

Topic		Replies	Views
[Discussion] Data certification on IC Developers	6	1894	September 19, 2022
Tackling CertifiedData in Motoko Language Support Motoko	36	3057	August 18, 2022
Awarded: ICDev.org Bounty #36 - Signing Tree and DER Encoding - Motoko $10,000 Bounties & RFPs	31	2144	June 30, 2023
Certified Assets from Motoko (PoC/Tutorial) Programs & Applications	14	2475	July 31, 2023
Certified variables Developers	2	96	August 13, 2024

Recommended usage of CertifiedData

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