Hardware non-deterministic random byte generator

1. A random byte generator comprising:

a noise source configured to generate a noise signal, said noise source which comprises no more than three discrete transistors, a first one of the discrete transistors having a collector which is not connected and an emitter-base PN junction that creates the noise signal for said noise source;

a digitizer possessing a voltage input range and a resolution of no less than two bits and configured to digitize the noise signal from said noise source; and

a processor configured to apply pre-defined rules for selecting bits captured by said digitizer and to generate random bit strings by combining said selected bits.

2. A random byte generator according to claim 1 wherein said noise source amplifies said noise signal to provide a peak-to-peak random voltage amplitude matching said voltage input range of said digitizer.

3. A random byte generator according to claim 2 wherein said noise source includes a final stage centering the continuous component of said peak-to-peak random voltage amplitude in the middle of said digitizer voltage input range.

4. A random byte generator according to claim 1 wherein said pre-defined rules include rules of selecting the least significant bits digitized by said digitizer and of excluding at least the most significant bit digitized by said digitizer.

5. A random byte generator according to claim 4 wherein said digitizer has a ten bits resolution and said pre-defined rules consist in selecting the six least significant bits digitized by said digitizer.

6. A random byte generator according to claim 1 wherein said processor is configured to perform said combining said selected bits by concatenating into bytes the bits selected by said processor.

7. A random byte generator according to claim 1 wherein said discrete transistors are of the type 2N3904.

8. A random byte generator according to claim 1 wherein said noise source comprises at a respective output thereof a low pass filter to comply with electromagnetic compatibility regulations.

9. A method for generating random byte including:

generating a noise signal with a noise source, said noise source which comprises no more than three discrete transistors, a first one of the discrete transistors having a collector which is not connected and an emitter-base PN junction that creates the noise signal for said noise source;

digitizing the noise signal from said noise source with a digitizer possessing a voltage input range and a resolution of no less than two bits;

applying in a processor pre-defined rules for selecting bits captured by said digitizer; and

combining in said processor said selected bits for generating random bit strings.

10. A method according to claim 9 further including:

amplifying said noise signal to provide a peak-to-peak random voltage amplitude matching said voltage input range of said digitizer; and

centering the continuous component of said peak-to-peak random voltage amplitude in the middle of said digitizer voltage input range.

11. A method according to claim 10 wherein said digitizer has a ten bits resolution and said pre-defined rules consist in selecting the six least significant bits digitized by said digitizer.

12. A method according to claim 9 wherein said pre-defined rules consist in selecting the least significant bits digitized by said digitizer and excluding at least the most significant bit digitized by said digitizer.

13. A method according to claim 9 wherein said combining said selected bits comprises concatenating into bytes the bits selected by said processor.

14. A method according to claim 9 wherein the processor is part of a postal security device.

15. A method according to claim 14 wherein whenever a health test fail error is generated by the random byte generator, the postal security device deletes a master key, which is required to access all critical security parameters and data.