tempo-consensus

The tempo-consensus crate implements Tempo’s consensus validation logic, extending Ethereum’s consensus rules with Tempo-specific block and transaction validation.

Installation

[dependencies]
tempo-consensus = "0.1.0"

Core Types

TempoConsensus

Main consensus implementation for Tempo.

use tempo_consensus::TempoConsensus;
use std::sync::Arc;
use tempo_chainspec::TempoChainSpec;

// Create consensus validator
let chain_spec = Arc::new(TempoChainSpec::mainnet());
let consensus = TempoConsensus::new(chain_spec);

Source: crates/consensus/src/lib.rs:36-50

Header Validation

Implements HeaderValidator<TempoHeader> trait.

validate_header

Validates a sealed header against consensus rules.

use tempo_consensus::TempoConsensus;
use reth_primitives_traits::SealedHeader;
use tempo_primitives::TempoHeader;

let consensus = TempoConsensus::new(chain_spec);
let sealed_header: SealedHeader<TempoHeader> = get_header();

// Validate header
consensus.validate_header(&sealed_header)?;

Validation Rules:

Standard Ethereum checks (via inner EthBeaconConsensus):
- Valid PoW/PoS seal
- Valid extra data size (≤ 10 KiB for Tempo)
- Valid EIP-1559 base fee
- Valid blob gas parameters
Timestamp validation:
- Must not be more than 3 seconds in the future
- Milliseconds part must be < 1000
Gas limit validation:
- sharedGasLimit must equal blockGasLimit / 10
- generalGasLimit must match expected value:
  - Pre-T1: (blockGasLimit - sharedGasLimit) / 2
  - T1+: Fixed at 30M

Source: crates/consensus/src/lib.rs:53-96

validate_header_against_parent

Validates a header against its parent.

let consensus = TempoConsensus::new(chain_spec);

// Validate child against parent
consensus.validate_header_against_parent(
    &child_header,
    &parent_header
)?;

Additional Validation:

Standard parent checks:
- Correct parent hash and number
- Valid gas limit adjustment
- Valid EIP-1559 base fee progression
- Valid EIP-4844 blob parameters
Timestamp progression:
- Child timestamp (with milliseconds) must be > parent timestamp

Source: crates/consensus/src/lib.rs:98-129

Block Validation

validate_body_against_header

Validates block body against header.

use tempo_primitives::BlockBody;

let consensus = TempoConsensus::new(chain_spec);

// Validate body matches header
consensus.validate_body_against_header(
    &block_body,
    &sealed_header
)?;

Verifies:

Transaction root matches
Withdrawal root matches (if present)
Ommer root matches (always empty for Tempo)

Source: crates/consensus/src/lib.rs:133-139

validate_block_pre_execution

Validates block before EVM execution.

use reth_primitives_traits::SealedBlock;
use tempo_primitives::Block;

let consensus = TempoConsensus::new(chain_spec);
let sealed_block: SealedBlock<Block> = get_block();

// Pre-execution validation
consensus.validate_block_pre_execution(&sealed_block)?;

Validation Rules:

System transaction validation:
- All system transactions must be valid for the chain ID
- System transactions must have correct signature
End-of-block system transactions:
- Block must contain exactly 1 system transaction at the end
- System transaction must target Address::ZERO (subblock metadata)
System transaction order:
- Subblock metadata system tx must be last

Source: crates/consensus/src/lib.rs:141-183

validate_block_post_execution

Validates block after EVM execution.

use reth_primitives_traits::RecoveredBlock;
use alloy_evm::block::BlockExecutionResult;

let consensus = TempoConsensus::new(chain_spec);
let recovered_block: RecoveredBlock<Block> = execute_block();
let result: BlockExecutionResult<TempoReceipt> = get_result();

// Post-execution validation
consensus.validate_block_post_execution(
    &recovered_block,
    &result
)?;

Verifies:

Receipt root matches header
Gas used matches header
Blob gas used matches (if applicable)
Requests hash matches (if applicable)

Source: crates/consensus/src/lib.rs:186-193

Constants

ALLOWED_FUTURE_BLOCK_TIME_SECONDS

Maximum time a block timestamp can be in the future.

use tempo_consensus::ALLOWED_FUTURE_BLOCK_TIME_SECONDS;

// Blocks can be up to 3 seconds in the future
pub const ALLOWED_FUTURE_BLOCK_TIME_SECONDS: u64 = 3;

Source: crates/consensus/src/lib.rs:26

TEMPO_SHARED_GAS_DIVISOR

Divisor for calculating shared gas limit.

use tempo_consensus::TEMPO_SHARED_GAS_DIVISOR;

// shared_gas_limit = block_gas_limit / 10
pub const TEMPO_SHARED_GAS_DIVISOR: u64 = 10;

Shared gas limit is used for payment lane transactions. Source: crates/consensus/src/lib.rs:29-30

TEMPO_MAXIMUM_EXTRA_DATA_SIZE

Maximum size of extra data in block headers.

use tempo_consensus::TEMPO_MAXIMUM_EXTRA_DATA_SIZE;

// Max extra data: 10 KiB (vs 32 bytes for Ethereum)
pub const TEMPO_MAXIMUM_EXTRA_DATA_SIZE: usize = 10 * 1_024;

Larger than Ethereum’s 32 bytes to accommodate DKG ceremony data. Source: crates/consensus/src/lib.rs:33

System Transactions

Tempo blocks must include system transactions at the end for:

Subblock Metadata (required):
- Target: Address::ZERO
- Contains validator fee recipient mappings
- Encoded as RLP list of SubBlockMetadata structs

System transaction signature:

use alloy_primitives::{Signature, U256};

pub const TEMPO_SYSTEM_TX_SIGNATURE: Signature = 
    Signature::new(U256::ZERO, U256::ZERO, false);

Gas Limit Rules

Pre-T1 (T0 and earlier)

Gas limits are calculated dynamically:

let block_gas_limit = 500_000_000;
let shared_gas_limit = block_gas_limit / 10; // 50M
let general_gas_limit = (block_gas_limit - shared_gas_limit) / 2; // 225M

T1 and later (TIP-1000)

General gas limit is fixed at 30M:

let block_gas_limit = 500_000_000;
let shared_gas_limit = block_gas_limit / 10; // 50M  
let general_gas_limit = 30_000_000; // Fixed at 30M

References: TIP-1000 Source: Chain spec method general_gas_limit_at()

Example: Full Block Validation

use tempo_consensus::TempoConsensus;
use reth_consensus::{Consensus, FullConsensus};
use tempo_primitives::{Block, TempoReceipt};
use std::sync::Arc;

#[tokio::main]
async fn main() -> eyre::Result<()> {
    // Setup
    let chain_spec = Arc::new(TempoChainSpec::mainnet());
    let consensus = TempoConsensus::new(chain_spec);
    
    // Get block
    let sealed_block = get_sealed_block().await?;
    
    // 1. Validate header
    consensus.validate_header(sealed_block.header())?;
    
    // 2. Validate header against parent
    let parent = get_parent_header().await?;
    consensus.validate_header_against_parent(
        sealed_block.header(),
        &parent
    )?;
    
    // 3. Validate body against header
    consensus.validate_body_against_header(
        sealed_block.body(),
        sealed_block.header()
    )?;
    
    // 4. Pre-execution validation
    consensus.validate_block_pre_execution(&sealed_block)?;
    
    // 5. Execute block
    let (recovered_block, result) = execute_block(sealed_block)?;
    
    // 6. Post-execution validation
    consensus.validate_block_post_execution(
        &recovered_block,
        &result
    )?;
    
    println!("Block is valid!");
    Ok(())
}

Timestamp Precision

Tempo blocks include millisecond-precision timestamps:

use tempo_primitives::TempoHeader;

// Full timestamp calculation
let timestamp_ms = header.timestamp() * 1000 + header.timestamp_millis_part;

// When validating against parent:
let parent_timestamp_ms = parent.timestamp() * 1000 + parent.timestamp_millis_part;
assert!(timestamp_ms > parent_timestamp_ms);

Source: crates/consensus/src/lib.rs:121-126

Error Handling

Consensus validation returns ConsensusError:

use reth_consensus::ConsensusError;

match consensus.validate_header(&header) {
    Ok(_) => println!("Valid header"),
    Err(ConsensusError::TimestampIsInFuture { timestamp, present_timestamp }) => {
        eprintln!("Block timestamp {timestamp} is in the future (now: {present_timestamp})");
    }
    Err(ConsensusError::Other(msg)) => {
        eprintln!("Validation error: {msg}");
    }
    Err(e) => {
        eprintln!("Error: {e}");
    }
}

JSON-RPC Methods

Rust Crates

tempo-consensus

Installation

Core Types

TempoConsensus

Header Validation

validate_header

validate_header_against_parent

Block Validation

validate_body_against_header

validate_block_pre_execution

validate_block_post_execution

Constants

ALLOWED_FUTURE_BLOCK_TIME_SECONDS

TEMPO_SHARED_GAS_DIVISOR

TEMPO_MAXIMUM_EXTRA_DATA_SIZE

System Transactions

Gas Limit Rules

Pre-T1 (T0 and earlier)

T1 and later (TIP-1000)

Example: Full Block Validation

Timestamp Precision

Error Handling

See Also

Build docs developers (and LLMs) love

JSON-RPC Methods

Rust Crates

Documentation Index

​Installation

​Core Types

​TempoConsensus

​Header Validation

​validate_header

​validate_header_against_parent

​Block Validation

​validate_body_against_header

​validate_block_pre_execution

​validate_block_post_execution

​Constants

​ALLOWED_FUTURE_BLOCK_TIME_SECONDS

​TEMPO_SHARED_GAS_DIVISOR

​TEMPO_MAXIMUM_EXTRA_DATA_SIZE

​System Transactions

​Gas Limit Rules

​Pre-T1 (T0 and earlier)

​T1 and later (TIP-1000)

​Example: Full Block Validation

​Timestamp Precision

​Error Handling

​See Also

Build docs developers (and LLMs) love

Installation

Core Types

TempoConsensus

Header Validation

validate_header

validate_header_against_parent

Block Validation

validate_body_against_header

validate_block_pre_execution

validate_block_post_execution

Constants

ALLOWED_FUTURE_BLOCK_TIME_SECONDS

TEMPO_SHARED_GAS_DIVISOR

TEMPO_MAXIMUM_EXTRA_DATA_SIZE

System Transactions

Gas Limit Rules

Pre-T1 (T0 and earlier)

T1 and later (TIP-1000)

Example: Full Block Validation

Timestamp Precision

Error Handling

See Also