eth2.0-specs/fork_choice/safe-block.md

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# Fork Choice -- Safe Block
## Table of contents
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- [Introduction](#introduction)
- [`get_safe_beacon_block_root`](#get_safe_beacon_block_root)
- [`get_safe_execution_block_hash`](#get_safe_execution_block_hash)
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## Introduction
Under honest majority and certain network synchronicity assumptions
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there exists a block that is safe from re-orgs. Normally this block is
pretty close to the head of canonical chain which makes it valuable
to expose a safe block to users.
This section describes an algorithm to find a safe block.
## `get_safe_beacon_block_root`
```python
def get_safe_beacon_block_root(store: Store) -> Root:
# Use most recent justified block as a stopgap
return store.justified_checkpoint.root
```
*Note*: Currently safe block algorithm simply returns `store.justified_checkpoint.root`
and is meant to be improved in the future.
## `get_safe_execution_block_hash`
```python
def get_safe_execution_block_hash(store: Store) -> Hash32:
safe_block_root = get_safe_beacon_block_root(store)
safe_block = store.blocks[safe_block_root]
# Return Hash32() if no payload is yet justified
if compute_epoch_at_slot(safe_block.slot) >= BELLATRIX_FORK_EPOCH:
return safe_block.body.execution_payload.block_hash
else:
return Hash32()
```
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*Note*: This helper uses beacon block container extended in [Bellatrix](../specs/bellatrix/beacon-chain.md).