Digital Signatures Based on Invertible Watermarks for Video Authentication
For verification and authentication of the video material and recovery of the original video several security mechanisms are required. The security techniques to realize this solution are introduced in :
The verification of the integrity is verified by hash functions.
Authenticity is verified by digital signatures using asymmetric cryptography and hash functions. The introduced scheme from  uses RSA signatures. The private key of the digital signature mechanism is used to sign the data and the corresponding public key is used for verification of the encrypted data. If the data can be verified the corresponding private key was used for the digital signature generation and the data seems to be authentic as well integer.
Furthermore the original content can be reproduced by inverting of the watermark with the well know techniques of Fridrich et al. . Additional secret key cryptography (symmetric crypt function) protects the reproduction. The invertibility is necessary, because we use a digital watermark to embed the authentication message and signature into the media itself. Digital watermark, in this application fragile watermark, changes the data and the original data cannot be reconstructing. To invert the data, the watermark must be removed and the original data reconstructed. The watermark embeds the information into a non visual or acoustical channel of the data after the original data of the channel were compressed and encrypted. The compression realizes the new space for the watermark consisting of the encrypted selected data and security information.
- 1.Dittmann, J., Steinebach, M., Ferri, L.: Watermarking protocols for authentication and ownership protection based on timestamps and holograms. In: Proceedings of SPIE, San-Jose, January 2002. Security and Watermarking of Multimedia Contents IV, vol. 4675, pp. 240–251 (2002) ISBN 0-8194-4415-4Google Scholar