DIGITAL AUTHENTICATION WITH ANALOG DOCUMENTS

The present claim relate generally to steganographic encoding and decoding. For example, one claim recites a method including: using a programmed electronic processor, generating authentication information corresponding to semantic information to be carried on or in a document; and incorporating the authentication information on or in the document, in which incorporated authentication information is to be later obtainable from the document for comparison with the semantic information, and in which the authentication information is steganographically incorporated on or in the document so as to be machine-readable from the document with visible light scanning. Of course, other claims and combinations are provided too.