GetCheckpointNumber returns check-point block where header contains valset of current epoch.

GetSignatureAddress gets the signer address from the signature.

GetValSetAddresses returns the address of validators from the extra-data field.

PrepareCommittedSeal returns a committed seal for the given hash.

sigHash returns the hash signing.

WriteCommittedSeals writes the extra-data field of a block header with given committed seals.

WriteSeal writes the extra-data field of the given header with the given seals.

WriteValSet writes the extra-data field of the given header with the given val-sets address.