Abstract: A credit document connected to a customized document or card is formed of a watermarked paper support with at least one dotted safety coding in linear and cryptographic form on the basis of a key consisting of an individual code. The customized document or card incorporates a microchip for the memorization of the identification code and of at least one mathematical expression which encodes the fingerprint of one or more fingers of the user. The equipment for formation of the customized document or card, the credit documents and related validation includes a scanner for taking said fingerprints, compared with those of the owner of the customized document or card upon issuance of the document and during use at the point of sale. The watermarked paper support exhibits one or more copper-plate engraving print reliefs measured by a micrometric sensor integrated in the validation equipment. A customized credit card calls for memorization of the same parameters encoded in the related microchip.