Security documents with double variable codes

摘要

Security document, such a banknote, with which first and second data are associated, the two data items being linked by an algorithm code, with means provided for modification of said linking code. The invention also relates to a corresponding method for document authentication and an authentication machine. According to the method the two data items are read, the code version used to link the items is determined and correspondence between the two codes is verified. The authentication machine has means for reading the two security data and means for writing the second data item.