Abstract: A method of protecting an electronic document, the method comprising dividing an original document into data blocks; generating a corresponding hash value for each data block; generating a corresponding hash value for a group of data blocks (GOB); generating a hash tree structure based on the corresponding hash values for the data blocks and for the GOB; calculating a hash value of a root node of the hash tree structure, the root node having no parent in the hash tree structure; signing the hash value of the root node; and generating auxiliary authentication data; wherein said auxiliary authentication data enables authentication of portions of the electronic document based on a reconstruction of the hash tree structure.

Abstract: A method and apparatus for encrypting and decrypting data is disclosed which employs two or more cryptographic algorithms to achieve high throughput without compromizing security. The invention is especially useful for software implementation to protect large amounts of multimedia data over high-speed communication channels.

Abstract: A method, an apparatus and a computer program product are disclosed for protecting the legitimacy of an article (100), and in particular an electronic document, against forgery or fraud. Such articles include passports, credit cards, bank notes, lottery tickets, secure forms. The method includes the following steps: several watermarks (204, 224, 244) are generated independently (304, 306, 308) by different cryptographic watermarking mechanisms controlled utilising information permanently associated within the article or product (100); and each watermark is embedded in a linked cryptographic manner (160, 162, 164). Subsequently, the watermarks can be scanned and digitised (410). The authenticity of the article (100) can be determined by verifying the correctness of extracted watermarks and the encryption links (160, 162, 164) among them. Also disclosed is a method of embedding an invisible watermark (714) in an official seal (712) incorporated in an electronic article or document (700).

Abstract: The invention relates to the field of information security, and more specifically to a mechanism that provides XML with a relative level of security and method of access control on XML documents. The mechanism is applicable to all well-formed XML documents. The secure XML document generated by using this technology keeps the well-formedness of the source document. The invention is directed to providing encryption at the element level of the document.

Abstract: A method, apparatus and a computer program product are described for copy protecting encrypted documents in a client-server system using an unsecured communication channel. The client-server system has clients and a server for storing encrypted documents. Encrypted documents e(Ks, M) are received by a client from the server. Communications on a transmission channel between the client and the server are then authenticated. Such communications also include electronic payments initiated by a user using the client. Upon authenticating or payment, an encrypted document can then be decrypted. After decrypting, the unencrypted document is displayed but prevented from storage at any client unless re-encrypted using a host specific key KH associated with the client to thereby provide a re-encrypted document.

Abstract: A steganographic method is disclosed to embed an invisible watermark into an image. It can be used for copyright protection, content authentication or content annotation. The technique is mainly based on K-L transform. Firstly a block and cluster step 106 and cluster selection step 108 are performed to enhance the optimization of K-L transform 110 for a given image. Then a watermark is embedded 114 into the selected eigen-clusters. ECC (Error Correction Code) can be employed to reduce the embedded code error rate. The proposed method is characterized by robustness despite the degradation or modification on the watermarked content. Furthermore, the method can be extended to video, audio or other multimedia especially for multimedia databases in which the stored multimedia are categorized by their contents or classes.