A method for deterring information copying, includes: combining a watermark serial number incorporate in a given medium with a content serial number to create a combined serial number, the watermark serial number uniquely identifies the given medium, and the content serial number uniquely identifies a content stored on the given medium; creating a digital signature by encoding the combined serial number using a private key of a public/private key pair; imprinting the content serial number and the digital signature on the given medium; decoding the digital signature imprinted on the given medium using a public key of the public/private key pair to obtain the combined serial number; comparing the decoded combined serial number with the watermark serial number and the content serial number imprinted of the given medium; and in response to determining that both match the combined serial number, determining that the content is authentic.