Sender verification system for official documents based on watermarking technique

This paper proposes a sender verification system for official documents in Portable Document Format (PDF) using watermarking techniques in the two-dimensional discrete cosine transform (2D-DCT) domain. The proposed scheme is implemented in Java Programming Language for its portability. The main purpose of the proposed system is identifying the user and the device information where the document was generated. The proposed scheme consists of the sender and the receiver sides. In the sender side, the watermark sequence is generated using the device information, such as Media Access Control address, user-name, date and time when the document was generated, etc. the generated watermark sequence is then embedded into the document file using the Quantization Index Modulation (QIM) algorithm. In the receiver side, the watermark sequence is extracted from the received watermarked document file to verify if the origin of the document is correct or not. The proposed scheme provides a high watermark imperceptibility and robustness against JPEG compression.