Abstract: A hierarchical cryptographic system has distributed authority among different classes of units in the system. The system may comprise a trusted authority, a first unit authorized by the trusted authority to distribute public and private signature and encryption keys. A second unit accepts for use one or more of the keys only after performing a verification program using the public signature key of the trusted authority. The invention also comprises a unit of a cryptographic system having a processor and a read only memory. The read only memory has stored therein a verification program which includes a public signature key of a trusted authority, and the verification program is made a permanent part of the read only memory during the formation process of the read only memory prior to the application of electrical power to the read only memory.