A personal data/time notary device is embodied in a token device such as a "smart card". The portable notary device includes an input/output (I/O) port, which is coupled to a single integrated circuit chip. The I/O port may be coupled to a conventional smart card reading device which in turn is coupled to a PC, lap-top computer or the like. A tamper resistant secret private key storage is embodied on the chip. The private key storage is coupled to the processor which, in turn, is coupled to a permanent memory that stores the program executed by the processor. At least one clock is embodied on the card. A second clock 14 and a random value generator 10 are also preferably coupled to the processor. The device combines digital time notarization into a digital signature operation to ensure that a time stamp is always automatically present. The user does not need to be involved in any additional decision making as to whether time stamping is necessary.