Support for EIP-4844 Shard Blob Transaction

[AbdelStark]

Context

EIP-4844 introduces a new transaction type, using EIP-2718 mechanism.

As @gakonst mentioned:

Separately, I'd love to spend some cycles thinking how EIP4844 transactions could be added to Ethers as a new EIP2718 type. https://www.eip4844.com/

Originally posted by @gakonst in #1685 (comment)

Feature

Implement a new transaction type in ethers-rs to enable developers to use shard blob transactions.

According to the EIP specification, the new transaction type encoding is the following:

class SignedBlobTransaction(Container):
    message: BlobTransaction
    signature: ECDSASignature

class BlobTransaction(Container):
    chain_id: uint256
    nonce: uint64
    priority_fee_per_gas: uint256
    max_basefee_per_gas: uint256
    gas: uint64
    to: Union[None, Address] # Address = Bytes20
    value: uint256
    data: ByteList[MAX_CALLDATA_SIZE]
    access_list: List[AccessTuple, MAX_ACCESS_LIST_SIZE]
    blob_versioned_hashes: List[VersionedHash, MAX_VERSIONED_HASHES_LIST_SIZE]

class AccessTuple(Container):
    address: Address # Bytes20
    storage_keys: List[Hash, MAX_ACCESS_LIST_STORAGE_KEYS]

class ECDSASignature(Container):
    y_parity: boolean
    r: uint256
    s: uint256

SSZ encoding

The new transaction is then: a single byte BLOB_TX_TYPE (0x05) followed by an SSZ encoding of the SignedBlobTransaction container.

It means that ethers-rs needs a way to encode and decode using SSZ format. As far as I know, currently there is no way to use SSZ encoding. We should then think about how we want to add this encoding, some alternatives:

• 3rd party lightweight Rust library such as https://github.com/ralexstokes/ssz-rs
• extract SSZ features from lighthouse implementation
• from scratch Rust implementation

Open design questions

• Add some abstraction helper to provide a path to a file to generate the blob data from

External implementations and tooling

There is currently a Devnet v1 running with a Geth fork for the EL and a Prysm fork for the CL.

Geth

For the Geth fork this is the implementation of shard blob transactions: see data_blob_tx.go

blob-utils

blob-utils is a CLI tool to send and download blobs on the proto-danksharding devnet.

[gakonst]

Could you share a couple test vectors? I could work on a branch that does that, just would like to ensure I get the serialization right. I like the idea of using ssz-rs.

[AbdelStark]

Could you share a couple test vectors? I could work on a branch that does that, just would like to ensure I get the serialization right. I like the idea of using ssz-rs.

Please find a sample JSON file with test vectors here: eip4844_test_vectors_sample_1.json

The code to generate the sample is also available here: test-vectors

To generate new test vectors you can:

go test

Discord: https://discord.com/channels/595666850260713488/595701195843174434/1024344939959697498

[gakonst]

Sweet. Will give a shot by this weekend.

[gakonst]

Dived into this, rough notes below. The biggest thing we're missing is a Rust function for blobs.ComputeCommitmentsAndAggregatedProof(). Everything else is basic type defs and conversions.

Generating a proof will mean we need to also have the KZG G1 trusted setup parameters loaded. Presumably these would be loaded via the Provider/SignerMiddleware, and we could consider distributing them with the library as an optional feature.

ethers-rs / eip4844 changes

1. Find Rust KZG library which exposes what we need
   https://github.com/mdehoog/go-ethereum/blob/e5291efded799e80f6e8b77f21b45fa6bbc0b2d3/core/types/data_blob.go#L353-L398

2. Figure out how to SSZ serialize
   mdehoog/go-ethereum@fce14ba#diff-d32f17b8a6d7109add632096d016f4cb111673ad2168034ecbced8af07d77822R517

https://github.com/Inphi/eip4844-interop/pull/28/files#diff-8f4c9db42d0333036ce672478a2c1d190b9257f8277759f9f3b2985c1a01a3d6R63

1. new transaction type
   After confirmed -> Option? Like we do for BaseFee.
   https://github.com/mdehoog/go-ethereum/blob/e5291efded799e80f6e8b77f21b45fa6bbc0b2d3/core/types/data_blob_tx.go#L318

     		BlobVersionedHashes: versionedHashes,
   

   Submit with KZG Proof on new tx type
   https://github.com/Inphi/blob-utils/blob/4fab45306c1406e122a12cb7c0f0d28bb8a69afa/utils.go#L14-L50
   https://github.com/Inphi/eip4844-interop/blob/master/shared/blobs.go#L9-L45

   blobs := shared.EncodeBlobs(data)
   commitments, versionedHashes, aggregatedProof, err := blobs.ComputeCommitmentsAndAggregatedProof()

   How to pass the trusted setup? Add it as a builder-pattern parameter to the provider? And to the
   signer?

2. new header field
   https://github.com/mdehoog/go-ethereum/blob/eip-4844/core/types/block.go#L91-L92
   excess_blobs (camelcase)

3. test it out against prod https://github.com/Inphi/eip4844-interop/blob/69392f4ff7d6339dabcd9cb1f4bf65d4480f9600/tests/fee-market/main.go
   https://github.com/Inphi/blob-utils/blob/4fab45306c1406e122a12cb7c0f0d28bb8a69afa/download.go

Misc:

• add RANDOM, DATAHASH to Revm
  mdehoog/go-ethereum@e5291ef#diff-c21870801ba3133fda5991da046fbfd0f83999bda1008a4af84affca83ec5eb9R208

[gakonst]

We might be able to use this library for the proof / commitments gen https://github.com/crate-crypto/proto-danksharding-crypto/tree/master/crypto

[Inphi]

For ssz seralize, lighthouse's internal ssz crate is worth looking into as it's battle tested and used on mainnet.
It's a self contained package that doesn't depend on any lighthouse modules, so it can easily be included in ethers-rs. It's missing a few things for EIP-4844, like a Bytes48 ssz codec and hash_tree_root implementation needed for KZG commitments.

[gakonst]

Flagging @asn-d6's library too https://github.com/asn-d6/blobbers

[koloz193]

Any update on this? With 4844 approaching this seems like something that would be helpful