A method for an encryption of a data stream is provided. The method includes: 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 including a clocked state and a working state, and providing a second random number generator having a second cryptographic strength, wherein the second cryptographic strength is higher than the cryptographic strength. The method further includes switching the states of the at least two first random number generators using an output of the second random number generator and using 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, such that a ciphered data stream is created.