al-maisan / infra-4788

what is this?

This is demo software that shows the construction of merkle proofs for a single ehereum BeaconState property: "finalized_checkpoint.root".

how to build it

go mod tidy
make

The following command displays a short help text:

$ bin/pgen -h
proof generator - generates proofs for ethereum BeaconState data.
Usage:
  -blockp string
    	The full path to the BeaconBlock json file
  -statep string
    	The full path to the BeaconState SSZ-snappy file
  -timeout duration
    	Timeout for the HTTP request (default 10s)
  -url string
    	The URL to download the beacon chain data from (default "https://docs-demo.quiknode.pro/")

how to run it

run by downloading the most recent finalized beacon chain data

Just run bin/pgen to download the most recent finalized beacon block/state and it will compute the proof for it.

Example:

$ bin/pgen
2024-08-25T15:49:12+02:00 INF BeaconBlock, slot: 9814080, parent_root: d105e75cf23641d5fd725e8028a89b683b37b66905566413300591cc1a882a4f, state_root: 7a5a297644b332b413691ec46b46329addfd202151686a4533d72b033f7fa2db
2024-08-25T15:49:16+02:00 INF File successfully written Filename=bstate-9814080.1724593752
2024-08-25T15:49:16+02:00 INF BeaconState, slot: 9814080, parent_root: d105e75cf23641d5fd725e8028a89b683b37b66905566413300591cc1a882a4f

Please note: this writes 2 files:

• BeaconBlock data in json format to bblock.9814080
• BeaconState data in SSZ-snappy format to bstate-9814080.1724593752

You can use these files to re-run the program on the same block.

The output produced looks as follows:

{
  "slot": 9814080,
  "beacon_block_root": "320c55726160c7fad09077dcae4d6df1eb11227fe374c3d305594b5e3e279204",
  "beacon_state_root": "7a5a297644b332b413691ec46b46329addfd202151686a4533d72b033f7fa2db",
  "finalized_root": "5523029ad957d5049a7d2336d3a9cb31bbb20612aa05ffbedd9a6f14e944046f",
  "block_time": 1724592983,
  "index": 745,
  "leaf": "5523029ad957d5049a7d2336d3a9cb31bbb20612aa05ffbedd9a6f14e944046f",
  "hashes": [
    "00ae040000000000000000000000000000000000000000000000000000000000",
    "fd23d5277e46023ed819d9b25713dfb88ada62452e2a42c22d4500176a36901f",
    "21c0b67dcc28f8b0bd2fb1dbef45710f42c1613b9d0db3bc524e4a8e95c660fa",
    "b17b8a68401c41a894a5736755fafebcbf43860f95d838b15df6d283a7cc8e9d",
    "e8144504535c4b0315705cb0d24c1ac200ea0b1f77b60e5f7fcb2a4634d8d00b",
    "6791b76ab2bdd75660c63314765f4f0878b67fce5d0ff3cd3f29a35b6f94f275",
    "d105e75cf23641d5fd725e8028a89b683b37b66905566413300591cc1a882a4f",
    "cda7207fa2a3fdabbe5f0328dc2be26359b7ba23bbdd76ed1e9cb94142058593",
    "ef14734d032b181ae448830440035bddfe9e09618d74a2f4ee3b11ace5dc1bf9"
  ]
}

The bottom three properties (index, leaf, hashes) constitute the proof and are needed for validation along with block_time and beacon_block_root.

run using block data on the local file system

Example:

$ bin/pgen -blockp bblock.9814080 -statep bstate-9814080.1724593752|jq
2024-08-25T15:54:24+02:00 INF BeaconBlock, slot: 9814080, parent_root: d105e75cf23641d5fd725e8028a89b683b37b66905566413300591cc1a882a4f, state_root: 7a5a297644b332b413691ec46b46329addfd202151686a4533d72b033f7fa2db
2024-08-25T15:54:25+02:00 INF BeaconState, slot: 9814080, parent_root: d105e75cf23641d5fd725e8028a89b683b37b66905566413300591cc1a882a4f

The generated json is the same as shown above.

proof generation

This demo software generates a proof for the BeaconState finalized_checkpoint.root property.

It does this by

• fetching the most recent finalized BeaconBlock and the respective BeaconState
• unmarshaling both the BeaconBlock and the BeaconState
• converting them to merkle trees for the purpose of proof generation
• grafting the BeaconState subtree onto the BeaconBlock tree in order to gain a full merkle tree whose proofs culminate in the BeaconBlock root
• generating the actual proof
• printing it in json format

Please note: I have slightly extended the github.com/ferranbt/fastssz repository to enable the tree grafting.