Patent ID: 6556679
Filing Date: 2003-04-29
Classification: G11B,H04N

Abstract:
A copy-guard system comprising:first decoding means for decoding digital data, which is encoded and error-correction-coded, from an information recording medium in which key information encoded for the digital data is recorded; encoded digital data acquisition means for acquiring digital data encoded by error-correcting the digital data decoded by the first decoding means; detection means for detecting an error position and an error symbol value of the encoded digital data acquired by the encoded digital data acquisition means; identification information detection means for detecting an identification information that is replaced with a part of the digital data encoded and error-correction-coded based on the error position and the error symbol value detected by the detection means, wherein the identification information represents whether the information recording medium is original or copied; first determination means for determining whether a copy of the information recording medium is protected based on the identification information detected by the identification information detection means; and copy protection means for protecting a copy of the information recording medium based on determination results of the first determination means.