Method and apparatus for watermarking of digital content, method for extracting information

A watermarking apparatus comprising:

• a key generator that generates private and public keys corresponding to the user terminal;
• a data generator that generates watermark data containing user identity information corresponding to the user terminal and user details associated with the watermark data;
• an encryption part that generates encrypted data by encrypting the watermark data and the user details with the private key;
• a data transmitter that transmits the watermark data, the encrypted data, and the public key to a server;
• and
• a watermark embedder that receives digital content when authorized by the server and watermarks the digital content with the watermark data.

A data extraction method comprising:

• extracting first watermark data from a watermark embedded in digital content;
• extracting second watermark data from a database or blockchain by searching the database or blockchain using the first watermark data;
• decrypting encrypted data associated with the second watermark data using a public key associated with the second watermark data;
• extracting third watermark data contained in the decrypted data;
• comparing the first watermark data, second watermark data, and third watermark data, and, if all of the data matches, extracting user details contained in the encrypted data.