1. A method for encryption of a data stream, the method comprising: providing the data stream; providing at least two first random number generators having a first cryptographic strength, wherein each of the at least two first random number generators is switchable between states comprising a clocked state and a working state; providing a second random number generator having a second cryptographic strength, wherein the second cryptographic strength is higher than the first cryptographic strength; based on an output of the second random number generator, switching states of the at least two first random number; and generating a ciphered data stream utilizing an XOR-function for combining the data stream with an output of one of the at least two first random number generators which is in the working state.