$$ \newcommand \StateProof {\mathrm{SP}} \newcommand \StateProofInterval {\delta_\StateProof} $$

Light Block Header

A light block header is a structure containing a subset of fields from Algorand’s block header and the commitment of said block header.

Light block header contains the following components:

• The block’s seed, under msgpack key 0.

• The block’s hash, under msgpack key 1.

• The block’s genesis hash, under msgpack key gh.

• The block’s round, under msgpack key r.

• The block’s SHA-256 transaction commitment, under msgpack key tc.

Commitment

The light block header commitment for rounds \( (X \cdot \StateProofInterval, \ldots, (X+1) \cdot \StateProofInterval] \) for some number \( X \), defined as the root of a vector commitment whose leaves are light block headers for rounds \( X \cdot \StateProofInterval, \ldots, (X+1) \cdot \StateProofInterval \) respectively.

The hash function SHA-256 is used to create this vector commitment.