Video signals are encrypted so that only the privileged viewers can watch them. A layer coding unit divides video signals into two layers and encodes each layer. An encrypting unit encrypts the low-quality layer data items according to the setting signal from a secret level setting unit and supplies the encrypted signal to a combining unit. Another encrypting unit encrypts the high-quality layer data items according to the setting signal from a secret level setting unit and supplies the encrypted signal to the combining unit. Ideally the high-quality layer data items are encrypted at a secret level that is higher than the secret level used to encrypt the low-quality layer data items. The synthesized data from the combining unit is converted at a communication modem into communication data, which is transmitted to a reception apparatus.
The specification relates to a method and apparatus supporting multiple access, bi-directional data and multimedia transfer described over a hybrid fiber/coax (HFC) network, though applicable to transmissions over other media as well. The protocol associated with the present invention supports downstream broadcast transmission from headend to cable modem, and also provides for allocation of bandwidth for cable modems to transmit back to the headend. The protocol supports different access modes such as STM, ATM, and VL; within each subframe of a subframe/frame/masterframe structure. The protocol is utilized over a system which provides for forward error correction (FEC) and scrambling/descrambling, while eliminating the deleterious effects on the error correcting capability of the FEC due to the bit error spreading associated with a scrambling/descrambling function. The protocol adapts to changing demands for a mix of circuit and packet mode applications and allocates upstream and downstream bandwidth in response to the a variety of bursty and isochronous traffic sources.
The present invention provides methods, systems and apparatus for encrypting and for decrypting a data stream, for securely sending a data stream and for securely receiving a data stream, and for secure transmission of a data stream. The data stream, after at least a part of it being encrypted, is transmitted from a sender to a receiver via a channel. An exemplary method for encrypting comprises: adjusting encryption attributes during transmission; encrypting the data stream according to the adjusted encryption attributes; and transmitting the encrypted data stream and information of the encryption attributes to the receiver.
The present invention provides a data processing apparatus and method for merging secure and non-secure data. The apparatus comprises at least one processor operable to execute a non-secure process to produce non-secure data to be included in an output data stream, and to execute a secure process to produce secure data to be included in the output data stream. A non-secure buffer is provided for receiving the non-secure data produced by the non-secure process, and in addition a secure buffer is provided for receiving the secure data produced by the secure process, the secure buffer not being accessible by the non-secure process. An output controller is then arranged to read the non-secure data from the non-secure buffer and the secure data from the secure buffer, and to merge the non-secure data and the secure data in order to produce a combined data stream, the output data stream then being derivable from the combined data stream. It has been found that such an approach assists in improving the security of the secure data, and in reducing memory bandwidth requirements and the processing requirements of the processor.
In a method and a device for partial encryption and progressive transmission of images, a first section of the image file is compressed at reduced quality without decryption, and a second section of the image file is encrypted. Users having access to appropriate decryption keywords can decrypt this second section. The first section together with the decrypted second section can then be viewed as a full quality image. The storage space required for storing the first and section together is essentially the same as the storage space required for storing the unencrypted full quality image. By using the method and device as described herein storage and bandwidth requirements for partially encrypted images is reduced. Furthermore, object based composition and processing of encrypted objects are facilitated, and ROIs can be encrypted. Also, the shape of a ROI can be encrypted and the original object can be decrypted and restored in the compressed domain.
To make it possible to provide high-quality music signal regardless of the advertising voice superimposing position, an encrypted pure music signal input through a transmission medium and an unencrypted advertising voice signal are separated by a signal string separation section. A signal transform and combining section decodes the encrypted pure music signal and combines the decoded music signal with the advertising voice signal into a resultant signal of the music and advertising voice signals, then outputs the resultant signal to a code string combining section, which then combines the encrypted pure music signal and the resultant signal of the music and advertising voice signals and supplies the result to a recording section for recording the result on a magneto-optic disc.
