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Fork Choice -- Safe Block

Introduction

Under honest majority and certain network synchronicity assumptions 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_execution_block_hash

Note: retrieve_fast_confirmed_root() is an implementation dependent function that retrieves the most recent confirmed_root determined by the Fast Confirmation algorithm.

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def get_safe_execution_block_hash(store: Store) -> Hash32:
    safe_block_root = retrieve_fast_confirmed_root()
    safe_block = store.blocks[safe_block_root]

    if compute_epoch_at_slot(safe_block.slot) >= GLOAS_FORK_EPOCH:
        safe_block_bid = safe_block.body.signed_execution_payload_bid.message
        return safe_block_bid.parent_block_hash
    if compute_epoch_at_slot(safe_block.slot) >= BELLATRIX_FORK_EPOCH:
        return safe_block.body.execution_payload.block_hash
    else:
        # Return Hash32() if no safe block is yet available
        return Hash32()

Note: This helper uses beacon block container extended in Bellatrix and Gloas.