Peptides are responsible for a wide array of biological functions.  Therefore, identification and quantitative determination of these biomolecules, typically present at very low concentrations in complex mixtures, is a topic of intense interest at the present time.  Here, we report a stochastic sensing method to differentiate a series of short peptides, including molecules differing by only one amino-acid, by using an engineered staphylococcal alpha-hemolysin protein pore. This method employed single-channel recording with the planar lipid bilayer technique, where current modulation represents individual binding events.  The results demonstrate a clear relationship of dwell time and amplitude of the events to the length and the structure of peptides. Our experiments also show that the identity of a target peptide and its concentration can be revealed even in the presence of a mixture of several different peptide components.  Furthermore, a mixture of peptide solutions can clearly be simultaneously differentiated and quantified.