Tuesdays the USPTO issues new patents. Today's Spotlight patents concern the use of watermarking and fingerprinting. Assigned to Digimarc, the first of today's patents concerns transmarking of multimedia signals. Assigned to Microsoft, the second patent concerns the use of digital fingerprints for message authentication.
7,373,513, "Transmarking of multimedia signals," assigned to Digimarc.
A method of transmarking a watermarked media signal to adapt the watermark to the robustness and perceptibility constraints of a new environment. This transmarking method detects the first digital watermark in the media signal. It then embeds message information from the first digital watermark into a second digital watermark in the media signal before the media signal undergoes a transformation process. The second digital watermark is adapted to survive the transformation process. A variation of this method detects the first digital watermark in the media signal, converts the media signal to a different format, and embeds message information from the first digital watermark into a second digital watermark in the converted media signal. The second digital watermark is adapted to robustness or perceptibility parameters associated with the new format.
7,370,197, "Method and system for authenticating messages," assigned to Microsoft.
A method and system for authenticating a message is described, in which the message contains a network address, at least a portion of which is a digital fingerprint. Embedded in the message is data, such as a code, that indicates the size of the digital fingerprint. A device receiving the message uses the size data and, for example, the public key of the sender to attempt to reproduce the digital fingerprint. If successful, the device receiving the message verifies the identity of the sender.