Abstract:
A digital video disk controller for reading data from an optical disk and stores the data in a memory. The data is then read from the memory and encrypted by an arithmetic processor. The encrypted data is then transmitted directly to an external device, via an interface circuit, without first storing the encrypted data back into the memory. The number of memory accesses performed by the controller is thus reduced, providing for lower power dissipation and faster access to the read data.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a method of data transfer, and, more particularly, to an apparatus and a method of reading, encrypting, and transferring data read from a recording medium to an external device. 
     2. Description of the Related Art 
     Providing digital storage media, such as digital video disks (DVD), with copy protection mechanisms for protecting copyrighted data has become increasingly important It is desirable that a signal processor performing copy protection functions be implemented using a single chip processor. The signal processor must perform quantitative arithmetic processing, such as encryption, on the data read from the storage medium. The processed data is then transferred to an external unit or device, such as a personal computer. It would be advantageous to increase the speed of processing and transferring the data read from the recording medium to the personal computer. 
     FIG. 1 is a block diagram of a conventional DVD unit  50 . Specifically, the DVD unit  50  for reading an optical disk  51  serving as a recording medium comprises: a DVD controller  53  which functions as a signal processor, a memory (DRAM)  54  which provides a temporary storage space for data read from the optical disk  51 , and a micro processing unit (MPU)  55  which controls the signal processing operation of the DVD controller  53 . The DVD controller  53  reads data recorded on the optical disk  51  and applies quantitative arithmetic processing or encryption processing on the data before it is transferred to an external unit such as a personal computer  52 . 
     Specifically, the DVD controller  53  comprises an error correction circuit  58 , an encryption circuit  56  for encrypting the data read from the optical disk  51  and stored in the DRAM  54 , and an external interface (I/F) circuit  57  for enabling data communication with the personal computer  52 . The encryption circuit  56  comprises a cipher generator circuit  56   a  and an encryption arithmetic circuit  56   b , which uses cipher data generated by the cipher generator circuit  56   a  to apply an arithmetic operation on the data read from the DRAM  54  and stores the processed data back in the DRAM  54  as encrypted data. 
     The DVD controller  53  also transfers the encrypted data stored in the DRAM  54  to the personal computer  52  through the interface circuit  57 . The personal computer  52  then decodes the encrypted and transferred data to recover the data read from the optical disk  51 . 
     As a result of the ever increasing processing speeds of personal computers, there is a demand imposed on the DVD controller  53  to decrease the processing time required to read and encrypt the data read from the optical disk  51 . 
     However, the processing operation for the encryption requires: 
     (1) transferring the data stored in the DRAM  54  to the encryption circuit; 
     (2) transferring the encrypted data from the encryption circuit to the DRAM  54 ; and 
     (3) transferring the encrypted data stored in the DRAM  54  to the interface circuit  57 . 
     Thus, the DVD controller  53  must perform three accesses to the DRAM  54 , which stands in the way of achieving a higher rate of data throughput. 
     It is an object of the present invention to provide a data transfer method and a signal processor which enable a high rate of data transfer. 
     SUMMARY OF THE INVENTION 
     To achieve the above objective, the present invention provides a data transfer method consisting essentially of the steps of: successively reading data to be transferred which is stored in a memory; applying quantitative signal processing to the read data; and transferring the processed data directly to an external unit. 
     The present invention further provides a signal processor, comprising: a memory for storing data to be transferred; an arithmetic circuit for successively receiving data to be transferred from the memory and successively applying signal processing to the data using quantitative data; and an interface for receiving the processed data directly from the arithmetic circuit and for successively transferring the processed data to an external unit. 
     The present invention provides a signal processor, comprising: a memory for storing data to be transferred; an encryption arithmetic circuit for successively receiving the data to be transferred from the memory and for successively encrypting the data using cipher data to produce encrypted data; and an interface for receiving the encrypted data directly from the encryption arithmetic circuit and successively transferring the encrypted data to an external unit. 
     The present invention further provides a digital video disk unit for reading data recorded in an optical disk, comprising: a memory for storing data to be transferred which is read from the optical disk; a signal processor for processing the data to be transferred; and a control unit for controlling the signal processor, wherein the signal processor comprises: an encryption arithmetic circuit which successively receives the data to be transferred from the memory and successively encrypts the data using cipher data to produce encrypted data; and an interface which receives the encrypted data directly from the encryption arithmetic circuit and successively transfers the encrypted data to an external unit. 
     Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention, together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which: 
     FIG. 1 is a schematic block diagram of a conventional DVD unit; 
     FIG. 2 is a schematic block diagram of a DVD unit according to a first embodiment of the present invention; 
     FIG. 3 is a schematic block diagram of a DVD unit according to a second embodiment of the present invention; and 
     FIG. 4 is a schematic block diagram of a DVD unit according to a third embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the drawings, like numerals are used for like elements throughout. 
     Referring to FIG. 2, a DVD unit  10  according to a first embodiment of the present invention will be described. An essential part of the DVD unit  10  is a signal processor, or DVD controller  11  for performing a copy protect function or performing the arithmetic operation for encryption. The DVD unit  10  comprises a micro processing unit (MPU)  12 , a rotation controller (not shown) which controls the rotation of an optical disk  13 , a drive head controller (not shown) which controls a drive head (not shown) used to read data from or write data to the optical disk  13 , and a motion controller (not shown) which moves the drive head in the radial direction. The MPU  12  controls the transfer of control signals between the rotation controller, the drive head controller and the motion controller for performing data read and write operations with respect to the optical disk  13 . 
     The DVD unit  10  further comprises a readable and writable dynamic random access memory (DRAM)  14 , which is formed by a single chip semiconductor memory and which acts as a temporary storage of data read from the optical disk  13  and data to be written to the optical disk  13 . 
     The DVD controller  11 , is preferably also formed by a single chip semiconductor integrated circuit. The DVD controller  11  communicates with the MPU  12  via control signals. In response to control signals from MPU  12 , the DVD controller  11  processes data read from the optical disk  13  by the drive head, and transfers the processed data to an external unit, such as a personal computer  15 . 
     The DVD controller  11  comprises an internal processor  20 , an error correction circuit  21 , an encryption circuit  22 , and an external interface (I/F) circuit  23 . Each of the circuits  20  to  23  is interconnected with each other through a bus  26 . The internal processor  20  communicates via a control signal with the MPU  12 , and controls the controller  11  on the basis of the control signal from the MPU  12  to read encrypted data stored on the optical disk  13  and transfer the encrypted data to the personal computer  15 . More particularly, data is read from the disk  13  and stored in the DRAM  14 . 
     In response to a control signal from the internal processor  20 , the error correction circuit  21  receives data which has been read from the optical disk  13  and stored in the DRAM  14 , and checks for errors in the received data. If there is an error in the received data, the error correction circuit  21  corrects the data, and stores it back in the DRAM  14 , to provide corrected data. 
     The encryption circuit  22  comprises a cipher generator circuit  24  and an encryption arithmetic circuit  25 . The cipher generator circuit  24  generates cipher data used to encrypt the data to be transferred to the personal computer  25 . The cipher generator circuit  24  is controlled by the internal processor  20 , and provides the cipher data to the encryption arithmetic circuit  25 , when instructed by the internal processor  20 . 
     The internal processor  20  also controls the encryption arithmetic circuit  25 , which successively receives the error corrected data stored in and read from the DRAM  14  (hereafter referred to as “data to be transferred”) and the cipher data from the cipher generator circuit  20 . The encryption arithmetic circuit  25  applies a given arithmetic operation or encryption algorithm on the transferred data using the cipher data to produce encrypted data (which is to be transferred), which is sequentially transmitted to the interface circuit  23 . 
     The internal processor  20  is also capable of initiating transferring of data directly from the DRAM  14  to the personal computer  15  via the interface circuit  23  without applying encryption to the data, in response to a control signal from the MPU  12 . In this instance, the cipher generator circuit  24  is not instructed to produce cipher data by the internal processor  20  and the encryption arithmetic circuit  25  successively supplies the data from the DRAM  14  to the interface circuit  23  without performing any encryption processing. Alternatively, the data may be read from the DRAM  14  and transferred to the interface circuit  23  over the bus  26 . 
     The interface circuit  23  receives encrypted data or non-encrypted data from the encryption arithmetic circuit  25 , and sequentially delivers it to the personal computer  15 . The interface circuit  23  also functions to receive data from the personal computer  15  and transfer it to the DRAM  14 . 
     The operation of the DVD controller  11  will now be described terms of the flow of data through the controller  11 . 
     The MPU  12  communicates with the internal processor  20  to initiate the transferring of data from the DVD controller  11  to the personal computer  15 . First, data is read from the optical disk  13  and stored in the DRAM  14 . The data stored in the DRAM  14  is then transferred to the error correction circuit, by way of the bus  26 . The error correction circuit  21  performs error detection and correction on the data using such methods as are known by those of ordinary skill in the art. The error corrected data is then stored back in the DRAM  14 . Next, the data is transferred to the encryption arithmetic circuit  25 , which encrypts the data using cipher data generated by the cipher generation circuit  24 . Data encryption algorithms are well known by those of ordinary skill in the art and thus, the particular encryption algorithm used need not be discussed in detail in order to understand the present invention. After the data has been encrypted, the encryption arithmetic circuit  25  transfers the encrypted data directly to the external interface circuit  23 , which in turn transfers the encrypted data to the personal computer  15 . The encrypted data transferred to the personal computer  15  may be decoded by the personal computer  15  in order to recover the original data read from the optical disk  13 . 
     As discussed above, the data stored in the DRAM  14  is encrypted by the encryption arithmetic circuit  15  and then immediately transferred to the personal computer  15  via the external interface circuit  23 . That is, the encrypted data is not first stored back into the DRAM  14  before being transferred to the personal computer  15 . This saves two DRAM  14  accesses, a write access to write the encrypted data to the DRAM  14  and a read access to read the encrypted data out of the DRAM  14  to transfer it to the personal computer  15 . Thus, the present embodiment increases the speed at which data is read and transferred from the optical disk  13  to the personal computer  15 . Further, a reduction in the number of DRAM  14  accesses also reduces power consumption. 
     Referring to FIG. 3, a DVD unit  100  according to a second embodiment of the present invention will now be described. The DVD unit  100  differs from the DVD unit  10  of the first embodiment in that an interface circuit  31  internally contains the encryption arithmetic circuit  25 . 
     As shown in FIG. 3, the interface circuit  31  comprises the encryption arithmetic circuit  25  and a selector  32 . In response to a control signal from the internal processor  20 , the encryption arithmetic circuit  25  receives data stored in the DRAM  14  and cipher data from the cipher generator circuit  24 , and encrypts the data using the cipher data, thus producing encrypted data, which is then sequentially delivered from the encryption arithmetic circuit  31  to the selector  32 . 
     The selector  32  receives the encrypted data from the encryption arithmetic circuit  31 , and also sequentially receives data directly from the DRAM  14 . In response to a control signal from the internal processor  20 , the selector  32  selects either the encrypted data or the data from the DRAM  14 , and transfers the selected data to the personal computer  15 . 
     It is to be noted that the interface circuit  31  also functions to receive data from the personal computer  15  and deliver it to the DRAM  14 . 
     The data flow in the DVD unit  100  will now be described. When encrypted data is to be transferred from the DVD unit  100  to the personal computer  15 , the internal processor  20  controls the cipher generator circuit  24 , the encryption arithmetic circuit  31  and the selector  32  via various control signals. 
     The encryption arithmetic circuit  31  sequentially receives the data read from the DRAM  14 , and encrypts the data using the cipher data from the cipher generator circuit  24 , thereby producing the encrypted data, which is delivered to the selector  32 . In response to a selector control signal, the selector  32  selects the encrypted data, and transfers it to the personal computer  15 . 
     In contrast, when the data stored in the DRAM  14  is to be transferred to the personal computer  15 , without utilizing encryption, the internal processor  20  delivers control signals to the cipher generator circuit  24 , the encryption arithmetic circuit  25  and the selector  32 , which indicate that encryption is unnecessary. In accordance with these control signals, both the cipher generator circuit  24  and the encryption arithmetic circuit  25  cease their operation for purpose of encryption. The selector  32  selects the data read from the DRAM in accordance with the control signal applied thereto, and then transfers it to the personal computer  15 . 
     With the DVD unit  100  of the second embodiment, the data is transferred to the personal computer  15  through the selector  32  immediately upon encryption, thus achieving a similar effect to that achieved by the DVD unit  10  of the first embodiment. 
     A DVD unit according to a third embodiment of the present invention will now be described with reference to FIG.  4 . The third embodiment differs from the second embodiment in the provision of a plurality of encryption arithmetic circuits  25   a-c  in its interface circuit  33 . 
     As shown in FIG. 4, the interface circuit  33  comprises a first, a second and a third encryption arithmetic circuit  25   a ,  25   b  and  25   c , and first and second selectors  25   a ,  25   b . Each of the encryption arithmetic circuits  25   a  to  25   c  receives mutually distinct cipher data from the cipher generator circuit  24 . In addition, each of the encryption arithmetic circuits  25   a-c  receives data read from the DRAM  14 . Specifically, one of the encryption arithmetic circuits  25   a-c  is selected by a control signal from the internal processor  20  to perform the encryption. The cipher generator circuit  24  then delivers cipher data which corresponds to one of the encryption arithmetic circuits  25   a-c  selected by the internal processor  20 . In this manner, the selected encryption arithmetic circuit  25   a-c  encrypts the data using the cipher data, thus delivering encrypted data to be transferred to the first selector  32   a.    
     The first selector  32   a  receives the encrypted data from one of the encryption arithmetic circuits  25   a-c . In addition, the first selector  32   a  receives a control signal from the internal processor  20  to select the encrypted data from the selected one of the encryption arithmetic circuits  25   a-c  and deliver it to the second selector  32   b.    
     The second selector  32   b  receives the encrypted data from the first selector  32   a  and also receives data read directly from the DRAM  14 . In response to a further control signal from the internal processor  20 , the second selector  32   b  selects either one of the encrypted data or the data from the DRAM  14 , and transfers the selected data to the personal computer  15 . 
     As discussed above, according to the third embodiment, a plurality of different types of encrypted data are produced by the encryption arithmetic circuits  25   a-c , thus enabling a variety of encryption algorithm to be utilized. 
     To produce encrypted data which are distinct from each other by the individual encryption arithmetic circuits  25   a-c , the encryption arithmetic circuits  25   a-c  may employ distinct encryption procedures rather than employing distinct cipher data. In such instance, the encryption arithmetic circuits  25   a-c  may receive the same or distinct cipher data. 
     It should be apparent to those skilled in the art that the present invention may be embodied in many other specific forms without departing from the spirit or scope of the invention. 
     For example, although the invention has been embodied in a DVD unit in the described embodiments, the invention may be embodied as any signal processor which may apply an arithmetic operation such as multiplying a quantitative value such as a coefficient to the data stored in the DRAM  14  or which may repeat such an arithmetic operation before transfer to an external unit. In such instance, the cipher generator circuit  14  is replaced by a data generator circuit which produces data representing a quantitative value such as a coefficient. In addition, the encryption arithmetic circuits  25  and  25   a-c  are replaced by an arithmetic circuit which performs an arithmetic operation between data within the DRAM  14  and the quantitative value. Again, the signal processor achieves a similar effect as achieved by the described embodiments. 
     In the described embodiments, the DVD controller  11  is embodied as a single chip semiconductor integrated circuit, however, it may be embodied into a single chip semiconductor integrated circuit for a portion thereof which excludes at least some of the cipher generator circuit  24  and the encryption arithmetic circuits  25  and  25   a-c . The cipher generator circuit  24  and the encryption arithmetic circuits  25  and  25   a-c  may be formed by a single chip semiconductor integrated circuit, which is separate from the DVD controller  11 . The cipher generator circuit  24  may be embodied as a single chip semiconductor integrated circuit. In addition, the cipher generator circuit  24  may be provided externally of the DVD controller  11  and cipher data may be delivered from the cipher generator circuit  24  to the controller  11 . Furthermore, the cipher generator circuit  24  may be provided externally of the DVD unit  10 , and the cipher data may be delivered from the external cipher generator circuit  24  to the DVD unit  10 . 
     Therefore, the present examples and embodiments are to be considered as illustrative and not restrictive and the invention is not to be limited to the details given herein, but may be modified within the scope and equivalence of the appended claims.