Abstract: A method of protecting user information against manipulations provides a high level of protection against any kind of manipulation without increasing the overhead significantly, by storing the user information in user channel packets of a user channel, assigning state information to the user channel packets, the state information being used to indicate if a user channel packet has been manipulated and/or is unstable or not, and storing the state information assigned to the user channel packets in an additional hidden channel embedded in the user channel, the state information assigned to a user channel packet being stored in the associated hidden channel packet.

Abstract: The invention relates to a method and an apparatus for defining entry points for a data stream, in particular a stream of audiovisual information. Entry points in the stream are defined at a predetermined interval. This may be a time interval, a byte interval or any other interval. It is an object of the invention to provide an entry point table having a limited size. This object is achieved by increasing the interval between entry points if the table exceeds a predetermined size. This size may be defined in bytes, in the number of entry points or even in the number of sub-tables. After redefinition of the interval between entry points, entry points are redefined. The invention also relates to an apparatus for defining the entry points and to a record carrier with a data stream incorporating entry points defined by the method according to the invention.

Abstract: The invention relates to a method and an apparatus for defining entry points for a data stream, in particular a stream of audiovisual information. Entry points in the stream are defined at a predetermined interval. This may be a time interval, a byte interval or any other interval. It is an object of the invention to provide an entry point table having a limited size. This object is achieved by increasing the interval between entry points if the table exceeds a predetermined size. This size may be defined in bytes, in the number of entry points or even in the number of sub-tables. After redefinition of the interval between entry points, entry points are redefined. The invention also relates to an apparatus for defining the entry points and to a record carrier with a data stream incorporating entry points defined by the method according to the invention.

Abstract: An apparatus for reading or writing user data stored block-wise in encrypted form on a storage medium. The apparatus includes a command interface for receiving and interpreting a read (or write) command. The read command includes a user data information specifying which user data are to be read. A reader reads the user data and a related encryption indicator from a block of the storage medium. The encryption indicator indicates if said user data is encrypted or not. The reader further reads a related key data identifier specifying which key data to use for decrypting the user data if said encryption indicator indicates that said user data are encrypted. A decryptor decrypts the user data using the key data.

Abstract: The invention relates to an apparatus for reading user data stored block-wise in encrypted form on a storage medium (4), the storage of which is divided into blocks, to an apparatus for writing user data block-wise onto a storage medium (4) and to corresponding methods. In order to inform the apparatus for read or writing, respectively, on the intended use of said user data, particularly if the user data is stored on the storage medium in encrypted form to inform the apparatus for reading about the encryption key for encrypting the user data before writing it on the storage medium or to inform the apparatus for writing about the decryption key for decryption the read user data before outputting it, it is proposed according to the present invention to add a processing information to the read or write command specifying how to process the user data and to provide processing means for processing the user data according to said processing information, e.g.

Abstract: The invention relates to an apparatus for reading or writing user data stored block-wise in encrypted form on a storage medium (4), the storage of which is divided into blocks, to an apparatus for writing user data block-wise in encrypted form onto a storage medium (4) and to corresponding methods. Since the user data is stored on the storage medium in encrypted form, the apparatus needs to be informed about the encryption key for encrypting the user data before writing it on the storage medium or about the decryption key for decryption of the read user data before outputting it.