Fully homomorphic encryption circuits in Cardano...

[mgajda]

It is a great feature for a smart contract to compute without decrypting the inputs and outputs.
This allows verifying private data, and knowledge of these.

For this, we would need to enable running zero knowledge proofs, or FHE circuits in Plutus.

Easiest way to do it would be to import an existing HE circuit library, and provide a reasonable cost estimate.
Please note that FHE/zkSNARKs are relatively expensive to compute so implementing them directly in Plutus may lead to unfeasibly complex transactions.

[matiwinnetou]

AFAIK there is no desire to put such things on Cardano L1 but have you heard of project midnight? https://midnight.iohk.io/

[mgajda]

I thought about Plutus to ensure smart contract interop.

Otherwise smart contract integration may require lots of separate infrastructure, possibly a sidechain.

[L-as]

@mgajda #283 will allow you to implement it yourself in Plutus

[mgajda]

@L-as Implementing it in Plutus would be definitely progress, but homomorphic encryption is infamously slow, so we will likely hit gas limit.

[mgajda]

@matiwinnetou Unfortunately project Midnight is fuzzy and unclear now. No capability has been released so far.

We want to build the product now and release soon.

[L-as]

@mgajda You split it up over multiple transactions. Depending on what you're doing, you could put the FHE into a SNARK?