In a general aspect, a multiple-entity root of trust is constructed and maintained for use in a cryptography system. In some aspects, a genesis data block includes genesis block data entries representing respective member entities of a root of trust consortium. A genesis block is generated by digitally signing the genesis data block. The genesis block is provided for use by end entities as a root of trust in a cryptography system. In some aspects, a hash of an existing block of a chain is obtained, and a data block comprising a data entry is generated. The data entry identifies an action by one or more member entities of the root of trust consortium. A new block of the chain is generated by digitally signing a combination of the data block and the hash of the existing block. The new block is provided for use by end entities as the root of trust in the cryptography system.