The present technology relates to secure mobile payment systems for interacting with traditional paper invoices. The method is characterized in that the compound is added such that the mass of the NO3\u2212 source is provided at the ratio of about 1 mg NO3\u2212 per 0. At least one stop is associated with each of the tumblers in order to limit the sliding path to conceal the unlocking position. Alternatively the flow-through can be mixed with a lower aliphatic alcohol prior to loading of the second column. The conversion module converts a key into an n-dimension format, the n-dimension format defines a coordinate system where each coordinate represents a memory location within the associated memory bank. The upper portion of the lower contact hole has the same width as the trench.