公开(公告)号：GB2365729B

公开(公告)日：2004-05-12

申请号：GB0109195

申请日：2001-04-12

Applicant: IBM

Inventor： DUBEY PRADEEP ,  JUTLA CHARANJIT SINGH ,  ANAND RAVINDRAN SAI ,  GANESAN PRASSANNA

IPC: H04L29/06 ,  H04L29/08

Abstract: A system and associated protocols for communication between two entities across a computer network operate such that the identities of the two entities remain concealed from each other, while ensuring that no third party is able to trace the existence of a conversation between them. The two entities correspond to each other through pseudonyms. The protocols are designed with an object to distribute trust so that an identity is not revealed by the compromise of any one agent involved in the execution of the protocol. No one agent can establish a correlation between a pseudonym and a physical address.

公开(公告)号：GB2365729A

公开(公告)日：2002-02-20

申请号：GB0109195

申请日：2001-04-12

Applicant: IBM

Inventor： DUBEY PRADEEP ,  JUTLA CHARANJIT SINGH ,  ANAND RAVUNDRAN SAL ,  GANESAN PRASSANNA

IPC: H04L29/06 ,  H04L29/08

Abstract: A system and associated protocols for communication between two entities across a computer network operate such that the identities of the two entities remain concealed from each other, while ensuring that no third party is able to trace the existence of a conversation between them. The two entities correspond to each other through pseudonyms. The protocols are designed with an object to distribute trust so that an identity is not revealed by the compromise of any one agent involved in the execution of the protocol. No one agent can establish a correlation between a pseudonym and a physical address.

公开(公告)号：GB2362240B

公开(公告)日：2004-04-28

申请号：GB0022615

申请日：2000-09-15

Applicant: IBM

Inventor： AGGARWAL GAURAV ,  DUBEY PRADEEP ,  KULSHRESHTHA ASHUTOSH ,  MARTENS MARCO ,  TRESSER CHARLES PHILIPPE LOUIS ,  WU CHAI WAH

IPC: G06T1/00 ,  H04N1/32

Abstract: A method is presented for marking high-quality digital images with a robust and invisible watermark. It requires the mark to survive and remain detectable and authenticatable through all image manipulations that in themselves do not damage the image beyond useability. These manipulations include JPEG "lossy" compression and, in the extreme, the printing and rescanning of the image. The watermark also has the property that it can detect if the essential contents of the image has changed. The first phase of the method comprises extracting a digest or number N from the image so that N only (or mostly) depends on the essential information content, such that the same number N can be obtained from a scan of a high quality print of the image, from the compressed form of the image, or in general, from the image after minor modifications (introduced inadvertently by processing, noise etc.). The second phase comprises the marking. This can be done in form of an invisible robust watermark, or in form of some visible signature or watermark.

公开(公告)号：GB2362240A

公开(公告)日：2001-11-14

申请号：GB0022615

申请日：2000-09-15

Applicant: IBM

Inventor： AGGARWAL GAURAV ,  DUBEY PRADEEP ,  KULSHRESHTHA ASHUTOSH ,  MARTENS MARCO ,  TRESSER CHARLES PHILIPPE LOUIS ,  WU CHAI WAH

IPC: G06T1/00 ,  H04N1/32

Abstract: A watermarking method for an image wherein a number N is embedded into an image as a invisible or visible robust watermark. The number N is generated from the essential components of the image such that the number N will be the same when generated from analysis of the image after processing (such as compression or printing) or noise introduces minor discrepancies or modifications which do not effect the images authenticity. The number N can be generated by performing a principal component analysis on a sample set of images with minor discrepancies or by using Wold's decomposition. Alternatively the image can be divided into n x n blocks and then transform coefficients are generated for each block, these are then quantized, the result is encrypted using a private key and this is then hashed using an algorithm to generate the number N. The authenticity of an image can be verified by generating the number N again when verifying and then comparing this to the number N embedded in the image, if the two do not match then it is considered that the image has been altered deliberately.