Abstract: A method is described for generating a secret sequence of values in a first device as a function of measured physical properties of a transmission channel between the first device and at least one second device. In this context, movements are detected by at least one sensor, and as a function of the detected movements, it is determined whether values of the physical properties of the transmission channel measured during the detected movements are suitable for generating the secret sequence of values.

Abstract: A method for authenticating a mobile device includes: probing by the mobile device a fading channel which connects the mobile device to a first radio base station; determining a secret held in common with the first radio base station as a function of a physical property of the fading channel; storing the in-common secret; receiving a first request for the in-common secret from a second radio base station; and, in response to the first request, sending a proof of knowledge of the in-common secret to the second radio base station.

Abstract: A method for generating a secret key via a reciprocal communication channel connecting a first communication node and a second communication node, wherein the first communication node obtains a first sample by a measurement of the communication channel, the first communication node performs a quantization of the first sample, the first communication node performs a matching of the quantized sample with the second communication node via the communication channel, during the matching, the first communication node obtains and quantizes a second sample by a second measurement of the communication channel and the communication nodes obtain the key from the samples by a privacy amplification.

Abstract: A method for generating a secret cryptographic key, which is common to a first node and a second node, with the aid of at least one helper node. The first node wirelessly transmits a first random sequence, the second node receives the first random sequence via a generally static reciprocal first communication channel, the second node receives a first signal, which is a function of the first random sequence, with the aid of the helper node, the second node derives the key from the first signal using the first random sequence, the second node wirelessly transmits a second random sequence, the first node receives the second random sequence, the first node receives a second signal, which is a function of the second random sequence, with the aid of the helper node, and derives the key from the second signal with the aid of the second random sequence.

Abstract: A method for authenticating a mobile device includes: probing by the mobile device a fading channel which connects the mobile device to a first radio base station; determining a secret held in common with the first radio base station as a function of a physical property of the fading channel; storing the in-common secret; receiving a first request for the in-common secret from a second radio base station; and, in response to the first request, sending a proof of knowledge of the in-common secret to the second radio base station.

Abstract: A first partner connected to a channel collects samples of a physical variable on the basis of a time-variable property of the channel; stores a first array of at least bivalent elements; stores a second array of at least bivalent elements, each element in the second array corresponding to a remaining element in the first array and representing a first state if the sample, to which the remaining element in the first array corresponds, is outside a limit range and representing a second state if the sample is within the limit range; receives a parity check bit from the second partner; subjects elements in the first array to a parity check using the parity check bit; and, if the parity check fails, determines a checked element in the first array whose corresponding element in the second array represents the second state, and inverts the determined element in the first array.

Abstract: For coupling a first communication partner with a second communication partner, a signal source sends a radio signal to the first communication partner via a first channel. The first communication partner ascertains a first measured value of a measuring variable related to the first channel during the receiving of the radio signal, ascertains a first comparative value as a function of the first measured value, and sends the first comparative value to the second communication partner. The second communication partner ascertains a first relationship measure between the first comparative value and a second comparative value, and couples with the first communication partner if the first relationship measure exceeds a specified threshold value.