1. A cryptographic processing device for securely performing a cryptographic processing operation in a manner resistant to discovery of a secret by external monitoring of said device's power consumption, comprising: (a) an interface for receiving data to be cryptographically processed; (b) an interface for receiving an external clock signal; (c) an interface for receiving a variable amount of power, said power consumption varying measurably during said performance of said operation; (d) an analog source of unpredictable information; (e) an oscillator using an analog process to generate an internal clock signal: (i) said process incorporating said unpredictable information to adjust the frequency of said clock signal generated by said oscillator; and (f) a processor: (i) configured to cryptographically process said data; and (ii) clocked by said internal clock signal to produce unpredictable temporal differences in power consumption variations among said cryptographic processing operations, thereby increasing the difficulty of determining said secret by collecting power consumption measurements.