Abstract: A client/server-based secure timekeeping computer system is provided. A secure-time server which is located in a physically trusted environment, includes a highly accurate time-of-day (TOD) clock, along with a key storage area containing a table of public/private key pairs corresponding to clients in the client/server network. The server encrypts a current time value from its TOD clock using a private key corresponding to a selected client. The encrypted time value is then sent to the client over an open communications channel. Each client in the network is equipped with its own secure timekeeping facility housed within the secure boundaries of a single, tamper-proof VLSI chip. Upon receipt of a secure-time transmission, a client uses its own copy of its private key to decrypt the time value, then loads the decrypted time value into its TOD clock.