Patent ID: 7127614

Claim:
A justification authenticating system comprising: a database for storing an identifier of a personal certificate and digital watermark information related to said identifier; a personal certificate containing said identifier; said personal certificate also containing a readable authentic image in which a digital watermark relative to said identifier is embedded; a read unit operable to read at least said authentic image from said personal certificate; a watermark information inquiring unit operable to extract digital watermark information corresponding to said identifier from said authentic image; and a watermark information comparing unit operable to judge whether said digital watermark information extracted by said watermark information inquiring unit from said personal certificate is identical to said watermark information stored in said database; and a unit operable to update said digital watermark information stored in said database and said digital watermark information embedded in said authentic image in said personal certificate each time said watermark information inquiring unit judges said digital watermark information to be justifiable.