Deterring information copying including deterrence of currency counterfeiting

A method for deterring currency counterfeiting, comprising:

• combining a watermark serial number comprised in a given piece of financial instrument paper of a plurality of financial instrument papers with a printed matter serial number to create a combined serial number, wherein the watermark serial number comprised in the given piece of financial instrument paper uniquely identifies the given piece of financial instrument paper, wherein the printed matter serial number uniquely identifies the printed matter printed on the given piece of financial instrument paper;
• creating a digital signature by encoding the combined serial number using the private key of the public/private key pair;
• and
• printing the printed matter serial number and the digital signature on the given piece of financial instrument paper to create a currency note.

A method for determining copying of digital content, comprising:

• combining a watermark serial number comprised in a given digital content storage of a plurality of digital content storages with a digital content serial number to create the combined serial number, wherein the watermark serial number uniquely identifies the given digital content storage, wherein the digital content serial number uniquely identifies a digital content stored on the given digital content storage;
• creating a digital signature by encoding the combined serial number using a private key of the public/private key pair;
• and
• imprinting the digital content serial number and the digital signature on the given digital content storage.