1. A method of decoding a data item string from a receiving data package using a physiological signal, the method comprising: identifying a plurality of signal features from a physiological signal; accessing a plurality of data pairs from the data package; identifying a subset of data pairs from the plurality of data pairs from the data package that correspond to one or more of the plurality of identified signal features from the physiological signal; reconstructing a polynomial equation based on the subset of data pairs such that a second element in each data pair of the subset of data pairs corresponds to an output of the reconstructed polynomial equation when a corresponding first element in the data pair is used as an input to the reconstructed polynomial equation; and deriving the data item string based on the coefficients of the reconstructed polynomial equation, wherein the physiological signal is an ECG signal, and wherein identifying the plurality of signal features includes identifying an R-peak corresponding to each cardiac rhythm cycle.