Article anti-forgery protection

A method of securing a given original article belonging to a batch of a plurality of original articles against forgery or tampering, each original article having its own associated article data and corresponding article digital data, comprising the steps of:

• for each original article of the batch, calculating by means of a one-way function an associated article digital signature of its corresponding article digital data;
• forming a tree based on the plurality of calculated article digital signatures for the original articles of the batch and comprising nodes arranged according to a given nodes ordering in the tree, said tree comprising node levels from leaf nodes, corresponding to the plurality of article digital signatures respectively associated to the plurality of original articles in the batch, to a root node of the tree, every non-leaf node of the tree corresponding to a digital signature by means of the one-way function of a concatenation of the above calculated digital signatures of its child nodes according to a tree concatenation ordering, the root node corresponding to a reference root digital signature, which is a digital signature produced by means of the one-way function of a concatenation of the above calculated digital signatures of the nodes of a penultimate nodes level in the tree according to said tree concatenation ordering;
• associating with the given original article a corresponding verification key being a sequence of the respective digital signatures, from the leaf nodes level to the penultimate nodes level, of every other leaf node having the same parent node in the tree that the leaf-node corresponding to the article digital signature of the given original article, and successively at each next level in the tree, of every non-leaf node having the same parent node in the tree that the previous same parent node considered at the preceding level;
• making available to a user the reference root digital signature of the tree;
• and
• applying on the given original article a machine readable security marking including a representation of its corresponding article digital data and its corresponding verification key,
• thereby obtaining a marked original article of which article data is secured against forgery or tampering.