Digitally watermarking documents associated with vehicles

The present invention provides steganographically embedded auxiliary data in motor vehicle documentation. The auxiliary data is used to authenticate the documentation or provide additional or redundant information pertaining to the documentation. Examples of such documentation are license plates, vehicle titles, insurance cards, registration cards and emissions documentation. In one implementation of the invention, a title document is digitally watermarked for authentication. The digital watermark may include a digital signature related to a buyer and a digital signature related to a seller. In another implementation, the transfer of motor vehicles is facilitated via digital watermarking. In still another implementation, a document includes two or more digital watermarks. The digital watermarks are intertwined with each other and at least one of the watermarks is intertwined with the document.