Direct block interface

Message types for the Block swap/share protocol

Verifying opaque block bytes

Use verifyBlockBytes when a transport or store only needs to validate and forward opaque bytes. It checks the CID version, codec code, and multihash without decoding the block value. Logical decoding should happen later, at the consumer boundary, after the bytes are authenticated.

checkDecodeBlock also verifies the digest before invoking a codec. A matching DAG-CBOR block can still allocate its decoded object graph, so callers handling attacker-selected CIDs should prefer verifyBlockBytes unless they explicitly need the logical value and enforce suitable resource bounds.