Patent ID: 6425081
Filing Date: 2002-07-23
Classification: G06T,H04L,H04N

Abstract:
An electronic watermark method used for a network system that includes a plurality of entities, wherein for the exchange of digital information by at least a first entity and a second entity of the plurality of entities,the first entity embeds an electronic watermark in the digital information, performs a first encryption process for the digital information, and transmits the resultant digital information to the second entity, the second entity embeds a second electronic watermark in the digital information received from the first entity, performs a second encryption process for the digital information, obtains a value by transforming the resultant digital information using a one-way compression function, and transmits the value and the resultant digital information to the first entity, and the first entity converts the digital information received from the second entity using the one-way compression function and, in accordance with whether the thus obtained value matches the value received from the second entity, performs a first decoding process related to the first encryption process for the digital information.