KR20120055186A - The method and implementation of the image recoding and playback device with nand flash memory and encryption and decryption function - Google Patents

Abstract

PURPOSE: A method for implementing an image storing and recovering device with an NAND flash memory and an encryption and decryption device is provided to prevent an illegal copy by encrypting and storing data in the NAND flash memory. CONSTITUTION: A TS(Transport Stream) is stored in a NAND flash memory(205) of an integrated MLC structure through a NAND flash controller(204). A decrypting unit(203) is connected to an input side and an output side of a NAND flash. An identification number of a PVR(Personal Video Recorder) is used as an encryption key.

Description

{The method and implementation of the Image Recoding and Playback device with NAND Flash Memory and Encryption and Decryption function}

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to the implementation of a storage and playback device for broadcast signals or personal creations, including video and audio, and is generally referred to as a personal video recorder or PVR (Persional Video Recorder) device.

PVR devices have various applications such as storing a received video signal, restoring a previous video within a few minutes, or storing a single movie, such as a time shift function. In addition, a hard disk drive (HDD) is applied as a storage medium, and recently, some products utilize an external storage medium using a USB communication function.

Like the conventional analog video tape recorder (VTR) method, the same basic function is used to record, reserve, and play video while watching a video using magnetic recording storage technology of VHS (Video Home System) method on a cassette tape. The present invention relates to a digital recorder used in a digital broadcasting signal system. In the case of digital satellite broadcasting, a MPEG-2 compressed TS (Transport Stream) stream is simultaneously watched and recorded on a hard disk drive (HDD). The PVR device is typically configured in such a way as to reproduce it if necessary. Because it is stored as a digital stream, infinite playback is possible, and since the hard disk is usually very large, recording for a long time of more than 24 hours is possible. However, hard disks used as recording storage media are very vulnerable to shock and durability. For example, when an external shock is applied during an operation such as recording or playback, the storage medium itself may be damaged due to physically scratching or breaking the header and surface of the disk due to the structural characteristics of the hard disk. Therefore, when a relatively long recording time is not required or when a video is played back within several hours such as a time shift, a storage medium that minimizes external shock, durability, or cost burden is required. An apparatus and method using a NAND flash memory are provided. And hard disk drive can be attached and detached. Especially, when storing to external media through USB communication, illegal copying of contents can be easily done. We want to prevent this by inserting encryption and decryption means before and after playback.

As described above, a broadcast recording apparatus using a hard disk drive as a storage medium for video content has the biggest disadvantages such as a failure of the storage medium against physical shock and reliability of the motor of the hard disk when used for a long time. have. In addition, there is a motor noise of the disk moving enough to be perceived externally during operation. In addition, since the hard disk drive is easily attached or detached, problems such as illegal copying of contents occur. Until now, there has been no suitable way to replace a storage medium such as a hard disk, but the NLC flash of MLC structure has emerged as a storage medium that can solve the above problems at once due to the price drop due to mass production and high integration. Of course, it is difficult to apply the capacity for long-term recording of more than 24 hours, such as a hard disk drive, but it is more cost-competitive for applications that perform recording function of several hours. In order to solve the problem of illegal copying of contents generated when an external storage medium is used, it is required to apply encryption means and decryption means before and after storage. Not only broadcast content, but especially personal content or creations are often exposed to third parties by illegal copying or accidents, so personal and social problems often occur. There is this.

1 shows a general structure of a conventional PVR receiver having a hard disk drive. Typically, high frequency broadcast band signals, such as satellite signals coming through the antenna 100 of the receiver, are converted into modulated baseband signals through the tuner section 101 and the signals are digitally measurable via the de-modulation section 102. It is converted into a transport stream (TS) stream in the form of a stream. TS streams are compressed with MPEG-based video and audio compression algorithms such as MPEG1, MPEG2, and MPEG4. De-Mux, which separates video and audio because they are not encrypted for free broadcasting, It is possible to restore a video signal and an audio signal that can be viewed through the MPEG2 decoder 106 directly through the 105, but a separate CAS (Conditional Access System) decryption unit 104 for decryption in case of paying broadcasting is provided. Decryption must be done through. The stream decoded through the CAS decryption unit can be restored to the MPEG2 decoder unit as in the case of free broadcasting. The reconstructed video signal is finally displayed through the analog output buffer unit 107 such as R, G, and B or the HDMI transmitter unit 108 outputting the digital output such as HDMI to meet the display standard. You can watch through.

The above process described the operation principle of the general satellite broadcasting recording apparatus.

In the present invention, the NAND flash storage medium 205 of the highly integrated MLC structure and the NAND flash controller unit 204 for controlling the recording and reproducing fundamentally to solve the physical shock or response speed, such as the recording and playback device. In order to prevent the leakage of the hard disk due to attachment or the leakage of contents due to illegal copying, and the like, the encryption and decryption means 203 before and after the storage medium.

According to the present invention as described above,

Recording devices incorporating hard disk drives are not only vulnerable to external physical shocks, but also relatively slow in response to the movement of physical headers within the hard disk for normal data retrieval. Of course, the response rate is acceptable in the average user's experience, but slower than memory like NAND flash. High-density MLC structure NAND flash is relatively inexpensive and requires a few hours of storage capacity, so the cost burden is much less than that of hard disk drive, which is the biggest problem of PVR. It is the best solution because the durability of the device is solved and there is no physical delay time for retrieving data.

In addition, by encrypting and storing the data before being stored in the NAND flash and restoring it in reverse during playback, it is possible to prevent illegal copying through copying of the storage medium, thereby further increasing the distribution of contents and reliability of the product.

As a result, in the present invention, it is reasonable to apply a hard disk drive in a product requiring a long recording time of 24 hours or more, but the high density MLC NAND flash is a storage medium of a recording device for a recording function of several hours. Application has solved the problem that contents are illegally copied through durability, fast response speed, and encryption and decryption means without problems of external shock.

Although the present invention has been described in connection with the above-mentioned preferred embodiments, it is possible to make various modifications or variations without departing from the spirit and scope of the invention. Accordingly, the appended claims are intended to cover such modifications or changes as fall within the scope of the invention.

1 is a configuration example of a PVR device using a typical hard disk drive (HDD)
2 is a configuration example of a PVR device including a password and a decoding unit for applying NAND flash to a storage medium and preventing illegal copying in the present invention.
3 is a structural example of a TS (Transport Stream) stream used as an international standard
4 shows an example of a process of generating an encryption and a decryption key used for encryption and decryption.
<Description of Main Parts of Drawing>
"Tuner part": A function for performing frequency shifting of a broadcast signal carried in a high frequency band to a baseband band
"De-modulation unit": A function of restoring a modulated signal to an original digital signal for transmission of a digital stream.
"CSA decryption unit": a function for restoring an encrypted stream in a broadcasting station in case of paying broadcasting
"D-mux part": A function of separating the packets of the TS stream into video and audio packets, respectively.
"MPEG2 Decoder": A function for restoring original video and audio from video or audio stream compressed with MPEG2 compression algorithm.
"RGB analog buffer": Analog signal output function for outputting restored video or audio signal to analog TV
"HDMI Transmitter": Signal output function to output reconstructed video and audio signal according to digital TMDS transmission standard
"Password / Decryption Unit": A function that performs encryption or decryption during storage and replay to prevent illegal duplication of data stored in NAND flash.
"NAND Flash Controller": A control function for controlling the process of storing or reading data in the NAND Flash memory.

Figure 2 shows the structure of the PVR device to be applied in the present invention. As shown in FIG. 1, the process of restoring the TS stream through the tuner 201 and the de-modulation unit 202 is the same. In FIG. 2, the output TS stream is stored in the NAND flash memory 205 of the MLC structure corresponding to the storage medium through the NAND flash controller unit 204 instead of storing the output TS stream. NAND flash capacity is an important specification of the product, so the required number is determined by calculating the required capacity according to the application. The capacity is calculated according to the following conditions.

Calculation of the capacity:

In the case of SD (TV quality, 720x480) video, the amount of data in the TS stream varies depending on the video, but is usually 2-4 Mbps (Mega bit per second), with an average data size of about 3Mbps. That is, 3M bits of data capacity per second and 180M bits for 1 minute. Here, 1M means 1 million (6 powers of 10), and 1G corresponds to 1000 times 1M. The NAND flash memory capacity of the commonly used MLC structure is 32G bit? It is available in single chip with 64G bits. The 32G NAND flash memory has a storage capacity of 177 minutes (32G bits / 180M bits = 177.7), allowing approximately 3 hours of continuous storage. Typically, a movie can be stored within two hours. Increasing the number of memories according to conditions increases the storage time accordingly. Therefore, there is no problem in applying to video recording equipment such as a PVR device which applies a recording function within several hours instead of a long recording function over 24 hours.

The video TS stream received in real time in the NAND flash of the MLC structure determined according to the above conditions can be stored and played back, or applied to a function such as a time shift.

In addition, an encryption and decryption unit 203 is connected to the input and output of the NAND flash. As described above, illegal copying is very problematic in the case of broadcast contents. Especially, in the case of PVR devices, storage media such as hard disks (HDDs) can be easily removed and attached from the installed devices, thereby allowing the stored contents to be copied. In the case of using an external storage medium, the copying becomes easier. Of course, in the case of a single-chip type memory such as NAND flash, it is very difficult to remove or request the device in the form of completely attached to the board, but in some cases, when attaching in the form of a slot, it may be partially removable. There is a possibility. To prevent this, encryption is performed using the unique number of the PVR device as the encryption key before storage, and decrypted using the unique number of the device as the decryption key again during playback. 4 shows a series of related processes using a diagram. The encryption method for encryption or decryption is a bi-directional block type encryption method using the same encryption and decryption keys. An AES (Advanced Encryption Standard) using a 64-bit or a 128-bit key, Triple DES (Data Encryption Standard), Common Scramble Algorithm (CSA) is used, and various other block ciphers can be applied. In particular, since the TS stream is a packet structure having a normalized standard of 188 bytes, the block-type encryption method is suitable.

3 shows a structure of an internationally standardized TS packet, in which a basic packet consists of 188 bytes, and the first 4 bytes correspond to a header. The first byte in the header of the packet is the sync signal (Sync) that indicates the beginning. It is fixed at 0x47 and the packet's unique number (PID, Packet ID), whether the packet is encrypted (SCR, Scrambling ContRol), and the packet type (AF). It indicates the continuity counter (CC) of the packet by adapting the field, and does not encrypt the content to be searched when classifying or playing the packet. The adaptation field data area, which contains the basic information of the stream, contains information such as the content type, name, title, and channel number, and thus does not perform encryption. The other area is called payload as video or audio data, and only this part is actually used in MPEG2 decoder unit for video and audio restoration. In the present invention, only the payload region excluding the header and adaptation field data is encrypted. A packet consisting of 188 bytes exists in three types, such as 301, 302, and 303. That is, 301 means that all 184 bytes except the header are video or audio data, and 302 indicates that all 184 bytes are composed of additional information such as name, title, channel number, etc. of the content. The case is an example of a case in which part is composed of adaptation field data and part is payload data. In the case of paying broadcasting, this is performed independently of the encryption performed by the broadcasting station, and is performed independently of the encryption and decryption functions in the PVR device, regardless of whether the broadcast content is encrypted.

4 illustrates a method for generating an encryption and a decryption key to be used in the encryption and decryption unit 203. When the device is powered on and started 401, first, each part of the basic device is initialized 402. This is a normal initialization process although it may vary depending on the configuration of the device and the conditions of the program developer. Then, 8 bytes or 16 bytes of unique information are read from a flash storage device (FLASH, 404) or a separate nonvolatile memory (EEPROM, 404) in which a program code is stored from an address of a predetermined location (403). If it is an initialization value (“0”) 405 where no unique information is input, the random data generator 406 generates a random value to use it as a unique number of the device. This will be stored in the location saved earlier. Of course, the designated location is not known to third parties other than the program developer.

The random value generated by the random data generation unit 406 is 8 bytes, which corresponds to 64 bits. The probability of occurrence of the same value is one of 64 powers (2 ＾ 64) of 2, which is impossible because of the astronomical probability. If a PVR device with a number is generated, it can be ignored.

The unique number generated in this way is converted into a modified value once through the hash function 410 and then used as a temporary key 411 of the encryption and decryption unit. This temporary key value can be used as a final password and decryption key, but when a user uses a password, a new key value combining the temporary key and the password is generated (CW, Code Word, 413) to encrypt and decrypt this value. For the final key 414.

In this way, if the device unique number and the user's password are used, the NAND flash or stream data is copied, and even if it is illegally leaked, it cannot be played on other PVR equipment.

Claims (5)

A method of implementing a storage and reproducing apparatus of a broadcast content, characterized in that the configuration of the PVR device stores and records the received broadcast stream in a nonvolatile memory such as a physically stable NAND flash memory. The method of claim 1,
An NAND flash controller for storing in a NAND flash memory, the method of implementing a NAND flash controller characterized in that the primary buffer is continuously buffered, and then sequentially and consecutively stored according to the storage characteristics of the NAND flash. In the configuration of the PVR device, in order to prevent leakage such as illegal copying of the received broadcast stream, storing the broadcast content, performing encryption before storing in a nonvolatile memory such as NAND flash and decrypting before playing. And a method of implementing the playback device, The method of claim 3, wherein
Encryption means for performing encryption before storage in a nonvolatile memory such as NAND flash, and generation of an encryption key for encryption is an encryption means characterized by using a combination of a unique number assigned to each device and a user's password; and Method of generating an encryption key, The method of claim 3, wherein
Decoding means for performing decryption before reproduction in a nonvolatile memory such as NAND flash, and generation of a decryption key for decryption using decryption means characterized in that a combination of a unique number assigned to each device and a user's password are used. Scheme for generating decryption keys,

Images