Abstract: Provided for herein is random number generator that includes a vertical cavity surface emitting laser, VCSEL, a mode separator and a photodetector, the random number generator further comprising a power source to drive the VCSEL in direct modulation mode. The VCSEL is adapted to emit, from an emitting section into space outside of a VCSEL cavity, laser light with two distinct laser modes of random relative strength that can propagate in a propagation direction away from the emitting section. The mode separator is arranged between the photodetector and the VCSEL in propagation direction to separate the two distinct laser modes from each other and to transmit one of the distinct laser modes to the photodetector.

Abstract: Apparatuses for transferring power from a power source to a computing device are provided for. The apparatuses include an entropy-generator for generating entropy. The apparatus is adapted for transferring the entropy to the computing device (such as a mobile computing device) when it is connected to the computing device. The device is adapted to power the entropy-generator with power received from the power source. Methods are also provided for. The methods include providing power and/or entropy to a computing device.