# [DRAFT] Eth1-Eth2 Communication Protocol

**This document has been deprecated and superseded by https://notes.ethereum.org/@n0ble/rayonism-the-merge-spec**

The Communication Protocol between eth2 and eth1 nodes sufficient for implementation of [Executable Beacon Chain](https://ethresear.ch/t/executable-beacon-chain/8271) proposal.

## Reference
- [eth2_produceBlock](#eth2_produceBlock)
- [eth2_insertBlock](#eth2_insertBlock)
- [eth2_setHead](#eth2_setHead)
- [eth2_finalizeBlock](#eth2_finalizeBlock)

### Constants
|Name|Value|
|-|-|
|LOGS_BLOOM_SIZE|256|
|MAX_TRANSACTIONS|2**32|
|MAX_PAYLOAD_SIZE|2**32|
|RECENT_BLOCK_ROOTS_SIZE|256|

### Structures

#### ExecutableData

class Transaction(Container):
    nonce: uint64
    gas_price: uint256
    gas: uint64
    to: bytes20
    value: uint256
    v: uint256
    r: uint256
    s: uint256
    input: ByteList[MAX_PAYLOAD_SIZE]    

class ExecutableData(Container):
    parent_hash: bytes32
    block_hash: bytes32
    coinbase: bytes20
    state_root: bytes32
    gas_limit: uint64
    gas_used: uint64
    receipt_root: bytes32
    logs_bloom: ByteVector[LOGS_BLOOM_SIZE]
    transactions: [Transaction, MAX_TRANSACTIONS]
    
    # for easier eth1-engine upgradability
    # will be removed later on
    difficulty: uint64

#### Eth1 Block

class BlockHeader:
    # = rpc_params.parent_hash / executable_data.parent_hash
    parent_hash: bytes32          
    uncles_hash: bytes32           # = EMPTY_LIST_HASH
    coinbase: bytes20              # = exec_data.coinbase
    state_root: bytes32            # = exec_data.state_root
    txs_root: bytes32              # = exec_data.txs_root
    receipts_root: bytes32         # = exec_data.receipts_root
    logs_bloom: bytes256           # = exec_data.logs_bloom
    difficulty: uint64             # = exec_data.difficulty
    timestamp: uint64              # = rpc_params.timestamp
    number: uint64                 # = exec_data.number
    gas_limit: uint64              # = exec_data.gas_limit
    gas_used: uint64               # = exec_data.gas_used
    mix_hash: bytes32              # = zero bytes
    extra_data: bytes32            # = rpc_params.randao_mix
    nonce: uint64                  # = 0

class Block:
    header: BlockHeader
    transactions: [Transaction]    # = exec_data.transactions
    uncles: []                     # = empty list

### eth2_produceBlock

Creates a new executable data on top of given parent.

#### Parameters
1. `parent_hash`: `Hash` - parent eth1 block hash.
2. `randao_mix`: `Root` - randao mix.
3. `slot`: `UInt64` - current slot.
4. `timestamp:` `UInt64` - timestamp, computed with the formula `genesis_time + slot * SECONDS_PER_SLOT`.
5. `recent_beacon_block_roots`: `SSZVector[Root, RECENT_BLOCK_ROOTS_SIZE]`.

#### Returns
1. `executable_data`: `ExecutableData`, SSZ encoded.

### eth2_insertBlock

Inserts a block into a chain and returns a result.

#### Parameters
1. `randao_mix`: `Root` - randao mix.
2. `slot`: `UInt64` - current slot.
3. `timestamp:` `UInt64` - timestamp, computed with the formula `genesis_time + slot * SECONDS_PER_SLOT`.
4. `recent_beacon_block_roots`: `SSZVector[Root, RECENT_BLOCK_ROOTS_SIZE]`.
5. `executable_data`: `ExecutableData`, SSZ encoded.

#### Returns
1. `Object` - the result of block processing:
- `result`: `Boolean`

### eth2_setHead

#### Parameters
1. `block_hash`: `Hash` - the hash of the head of the application chain.

#### Returns
1. `Object` - the result of processing:
- `result`: `Boolean`

### eth2_finalizeBlock

#### Parameters
1. `block_hash`: `Hash` - the hash of finalized eth1 block.

#### Returns
1. `Object` - the result of block processing:
- `result`: `Boolean`