Information recorder, information reproducer, recording media manufacturing system, and information recording media, method and program

Abstract

The present invention provides an information recording configuration that achieves both difficulty in reading and highly accurate reading. Highly confidential additional information such as encryption key is recorded in a groove signal. During recording of the additional information, a groove signal is recorded that has an amplitude offset setting commensurate with the bit value. During reading of the additional information, a signal R0 with no offset is estimated from a signal R1 read from the groove signal for a predetermined period, after which a difference signal C=R1−R0 is calculated and integrated for each of the predetermined periods so as to determine the direction of the amplitude offset for each period. This process achieves recording and reproduction of additional information that offers enhanced difficulty in reading and highly accurate reading at the same time.

Dependencies are inferred from the claim text.