The invention concerns a device for detecting the presence of a user to allow andor prevent access inside a motor vehicle, the vehicle comprising at least a decorative element fixed to the body proximate to an opening, the device comprising at least an electrode detecting the presence of a user and a processing circuit connected to the detecting electrode. Connected in parallel with each laser diode is a respective safety diode which has a higher band gap than its associated laser diode. A correlator computes the cross-correlation value of the phase-controlled specific frequency component signal and the input image signal. The yarn sending length F is corrected in such a manner that the difference between natural lengths L1, L2 of the rubber yarn 5, existing in the yarn route pathway under the set tension T1 and the actual tension T2, decreases. The method includes receiving, at the first mobile device, a second identifier from the second mobile device, the second identifier comprising user information related to a second user and the email to be shared.