An Analog of the Electronic Digital Signature Based on Codes Defining Images with Accuracy up to Affine Transforms

The first and long-standing option to protect a document from forgery (it is still used today) is the so-called “live” signature (or facsimile) and a clerical seal. However, nowadays the document flow is mostly electronic and often with a very large number of documents (electronic trading, bank payment systems, transactions in cryptocurrencies, etc.). The digital signature that emerged about thirty years ago works here. As a rule, the core of a digital signature is a function whose value is easily calculated for a given argument value, and the reverse, i.e., calculating the value of an argument given the value of a function, is very difficult. The article describes an analog of a digital signature on a different fundamental basis, using image codes that define them up to affine transformations.