Patent ID: 6741991
Filing Date: 2004-05-25
Classification: G06F,G06Q,G06T,G07F,H04L,H04N,Y10S

Abstract:
A data management method comprising:entering first user data as a first electronic watermark to first data content by a data management center; encrypting the first data content by the data management center using a first secret key; distributing the encrypted first data content from the data management center to a first user; distributing the first secret key and a second secret key from the data management center to the first user, the first and second secret keys being different from each other; decrypting the encrypted first data content by the first user using the first secret key; entering second user data as a second electronic watermark to the first data content by the first user before transferring the first data content from the first user to a second user; and re-encrypting the first data content by the first user using the second secret key before storing, copying, or transferring the first data content by the first user.