The invention relates to a product protection system whereby a product
piece is provided with a product-specific identification sequence (K)
which is converted into a coded check sequence (C), by means of an
encoding method (F1) using a secret encoding sequence (B). A product
control sequence is applied to or on the product piece which comprises
the coded check sequence (C), or a sequence derived therefrom. In order
to check the authenticity of the product piece, the product control
sequence is recorded by a control requester and transmitted by internet
to a product protection server structure. A decoded check sequence is
derived therein from the product control sequence by means of a decoding
method using a decoding sequence. The authenticity of the decoded check
sequence, or a sequence derived therefrom is checked and the result of
the authenticity check transmitted by internet to the control requester.