A weblog focused on interesting circuits, ideas, schematics and other information about microelectronics and microcontrollers.
Random bit generator
Simple, low-consumption and really unpredictable random generator, usable for cryptographic applications.
Authort says: ORB is hosted on a Microchip Technology 8-bit microcontroller, and uses one external resistor. A closed-loop process in which a capacitor is charged and discharged according to the contents of a bitstream generates random information entropy, and an A/D converter measures the capacitor’s voltage. The unpredictable low-order bits of the A/D results are "stirred" into an entropy pool, which is then processed through a cryptographic hash function (MD2). Part of the hash result is the random output and part of it forms the bitstream to continue the process.