A lightweight node in a decentralized network includes stores a blockchain with a plurality of blocks. The lightweight node adds blocks to the blockchain successively. A given block having a header and a body. The header includes a data merkle root generated as a root hash of a data merkle tree with one or more leaf nodes that are one or more hashes. A given hash being a hash of a combination of (1) a public key associated with a lightweight node of the decentralized network and (2) of a validity value associated with the public key indicating whether the public key is a valid public key. The data merkle root being insufficient for restoring the data merkle tree. But with a public key and an intermediate hash the date merkle root is sufficient for at least partly verifying the public key.