KR100820971B1 - Method of recording and playing decryption key in compressed audio file - Google Patents

Abstract

The present invention relates to a method for recording and reproducing a decryption key in a compressed audio file, wherein the decryption key for the MP3 audio file encrypted for the purpose of copyright protection is distributed in the header information of the MP3 audio file, In a playback device such as a player, the creator arbitrarily designates the MP3 audio file in the process of encrypting and recording the MP3 audio file by detecting and combining the encrypted decryption key distributed and recorded in the header information, and decrypting and restoring the encrypted recorded audio data. It is not necessary to store unique decryption keys separately in a playback device such as an MP3 player, and in a general playback device that does not include an algorithm for detecting and combining the decryption key recorded in the header information, it is encrypted for copyright protection. MP3 audio files prevent normal playback Very useful inventions that are able to kill,

MP3 audio files, encryption, decryption, copyright, header information, private

Description

Method for recording and reproducing a decryption key in compression audio file}             

1 illustrates a recording format for an MP3 audio file, which is one of general compressed audio files,

2 illustrates a configuration of an MP3 audio file in which a decryption key is recorded and distributed according to the present invention.

3 illustrates a configuration of an MP3 audio file in which a decryption key is distributed and recorded according to another embodiment of the present invention.

4 schematically illustrates a configuration of an MP3 player to which a compressed audio file playing method according to the present invention is applied.

5 is a flowchart illustrating an operation of a method of reproducing a compressed audio file according to the present invention.

※ Explanation of code for main part of drawing

10: memory card 20: microcomputer

30: audio processor 40: decoding and decoding program storage unit                 

50: liquid crystal display

The present invention relates to a method for recording and playing a decryption key in a compressed audio file, and more particularly, to decrypt audio data encrypted in a compressed audio file such as an MP3 (MPEG Audio 3) audio file. Recording a decryption key value in a compressed audio file that additionally records a decryption key value appropriately for a recording format of an MP3 audio file, detects it in a playback device such as an MP3 player, and enables decryption; and It relates to a regeneration method.

First, FIG. 1 illustrates a recording format for a general MP3 audio file. In the MP3 audio file, at least one frame having a fixed length of 4 bytes and at least one frame having an arbitrary variable length are included in the MP3 audio file. 128 bytes of information recorded on the MP3 audio file (File_Info), for example, title, album, production date and genre of the MP3 audio file. TAG information is recorded and included.

On the other hand, the audio data is compressed and recorded by the 'MPEG Audio 3' compression method in the frame, and the header information includes a frame sync bit (frame sync) and a version of the amppack audio data for synchronizing with the frame data. MPEG audio version ID bits to identify, protection bits to check for data transmission errors by CRC code, bit rate index bits to identify the bit rate of the data stream (Bitrate Index), Sampling Rate Frequency Index Bit (Sampling Rate Frequency Index) for identifying the frequency of the sampling rate, Padding Bit (Padding Bit) for padding null data, Private bit that can be arbitrarily specified by the user (Private Bit), Channel Bit, Stereo to indicate Stereo Channel or Dual Channel Mode Mode extension bit to indicate frequency band, etc. in false channel mode, copyright bit to indicate copyright protection, original bit to indicate whether to copy or original, and emphasis bit (Emphasis) is recorded to include.

Therefore, in a playback apparatus such as an MP3 player, a liquid crystal display is provided such that a user can check various information on the file by searching and reading the 128-byte tag information recorded at the end of the MP3 audio file. Performs a series of playback operations for displaying the screen on a display (LCD) or the like, and using the information recorded in the header information to restore and reproduce the audio data compressed and recorded in the frame area into high quality audio data. Done.

On the other hand, in recent years, as well as the playback devices such as the MP3 player that restores and reproduces the MP3 audio files to high-quality audio data as described above, Internet sites that provide the MP3 audio files without permission through the Internet As it emerges one after another, there is an urgent need for a copyright protection method for the MP3 audio files.

Accordingly, the compressed audio data recorded in the frame area of the MP3 audio file is encrypted by using a known encryption method, Read Solomon, or the like, and then compressed and recorded. The MP3 audio file can be decrypted and restored to the original audio data, thereby preventing unauthorized copying and playback of the MP3 audio file in any playback device in which the decryption key is not stored.

However, the encryption key as described above can be used as a unique key value specified by the producer in the process of encrypting and recording the MP3 audio file, so that a user having a playback device such as an MP3 player can There was a problem in that each decryption key for a large number of recorded MP3 audio files had to be stored in a playback device such as an MP3 player.

Therefore, the present invention was created to solve the above problems, and distributed the decryption key for the MP3 audio file encrypted for the purpose of copyright protection in the header information of the MP3 audio file, as well as the MP3 player. In a reproducing apparatus, there is provided a method for recording and reproducing a decryption key in a compressed audio file for detecting and combining the decryption key recorded in the header information so as to enable decryption and restoration of the encrypted recorded audio data. The purpose is to.

In the compressed audio file recording method according to the present invention for achieving the above object, in the method for encrypting compressed data consisting of a plurality of header portion and the frame portion, encrypting the compressed data by an encryption key Step 1 to do; Additionally generating a header part for storing the encryption key; And distributing and recording an encryption key in the additionally generated header part.

In addition, the method for reproducing an encryption key in a compressed audio file according to the present invention comprises the steps of: extracting an encryption key value distributed and stored in the header part in a method of decrypting encrypted compressed data including a plurality of header parts and a frame part; ; Combining the extracted encryption key values to complete an encryption key; And decrypting the encrypted compressed data using the encryption key.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of a decryption key recording method and a reproduction method in a compressed audio file according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 illustrates a configuration of an MP3 audio file in which a decryption key is distributedly recorded according to the present invention. As described above with reference to FIG. 1, the MP3 audio file includes a header having a fixed length of 4 bytes. (Header) and at least one frame having an arbitrary variable length is recorded including, and the tag (TAG) information of 128 bytes in which information (File_Info) for the MP3 audio file is recorded is recorded.

On the other hand, according to the encryption decryption key recording method according to the present invention, a plurality of headers record encrypted compressed audio data in the frame area and record decryption keys for decryption in the head recording section of the MP3 audio file. The information is distributed and recorded, and in particular, each of the header information is distributed and recorded in a private bit of a 1-bit length defined to be arbitrarily designated and used by a user.

For example, as shown in FIG. 2, when the security key is '0101', four header information (Headers 1, 2, 3, 4) recorded in the head recording section of the MP3 audio file are also shown. ), '0', '1', '0', and '1' are distributedly recorded.

On the other hand, at least one or more frames in which the decryption key is paired with the distributed recorded header information, for example, a frame corresponding to the first header information (Header 1), the guide information for the decryption key is non-encrypted data. A value of "1" for informing copyright protection is recorded in one-bit copyright bits each of which is included in the header information (Header 1,2, 3, 4). .

The 128-byte tag information recorded at the end of the MP3 audio file includes the decryption key in addition to various information on the title, album, production date and genre of the MP3 audio file. Is recorded including information for indicating how many header information is distributedly recorded.

Meanwhile, FIG. 3 illustrates a configuration of an MP3 audio file in which an encryption decryption key is distributed and recorded according to another embodiment of the present invention. As described above with reference to FIG. An embodiment in which the recording is included in an audio file but only one frame for recording the guide information for the encryption key is recorded. For example, as shown in FIG. ) Is '0101', four header information (Header 1,2,3,4) are continuously recorded in the head recording section of the MP3 audio file, and in the private bit of the continuously recorded header information, '0' ',' 1 ',' 0 ',' 1 'are distributedly recorded.

In addition, the entire length of the MP3 audio file can be shortened by selectively recording guide information on the decryption key as unencrypted data in a frame corresponding to the fourth header information (Header 4).

FIG. 4 schematically shows a configuration of an MP3 player to which a compressed audio file reproduction method according to the present invention is applied, which includes: a memory card 10 in which a plurality of MP3 audio files are recorded and stored; A microcomputer 20 for reading and combining the decryption key by reading the MP3 audio file recorded on the memory card according to a user's request; A decryption and decoding program storage unit 40 performing decryption operation using the decryption key detected and combined with the microcomputer, and decoding the decrypted compressed audio data into original audio data; An audio signal processor (30) for processing the decoded and decoded audio data into a reproduced audio signal; A liquid crystal display 50 for displaying information on the operation, etc. may be included, and the decryption and decoding program storage unit 40 may be integrally included in the microcomputer.

On the other hand, in the microcomputer 20, as shown in FIG. 5, when a playback request for an MP3 audio file is received from the user (S10), the microcomputer 20 searches for an arbitrary MP3 audio file recorded and stored in the memory card 10. Then, the tag information recorded at the end of the MP3 audio file requested for playback is retrieved, and the recorded file information included in the tag information, for example, title, album, and production of the MP3 audio file Various information about the date, the genre, and the like are displayed on the screen through the liquid crystal display, and information indicating how many header information are encrypted and decoded is detected (S11).

Then, the head recording section of the MP3 audio file requested to be reproduced is searched (S12), and a plurality of header information recorded in the head recording section, for example, as shown in Figs. When the data is distributed and recorded in the four header information, the private bits of the first to fourth header information are detected. In the microcomputer 20, prior to this, the copyright of the first to fourth header information is determined. Copyright) It is checked whether or not the bit value '1' indicating copyright protection is recorded in the bit (S13).

On the other hand, if the bit value '1' indicating copyright protection is recorded (S14), the microcomputer 20 decodes the decryption key value distributed and recorded in the private bits of the first to fourth header information. After retrieval and storage (S15), the retrieved and stored decryption key values are combined to complete the encryption decryption key value '0101' (S16).

Then, by using the combined decryption key and the decryption program stored in the decryption and decoding program storage unit 40 through the above-described process, each of the compressed audio data encrypted in the frame area is decrypted. In operation S17, the decoded and decoded audio data may be restored to the original audio data by using the decoding program stored in the decoding and decoding program storage unit 40, and then output to the audio signal processor 30.

Accordingly, the audio signal processing unit performs a normal playback signal processing operation of processing the decoded and restored audio data into a playback audio signal for reproduction.

On the other hand, if the check result, '0' is recorded in the copyright bit, it is determined that the copyright protection for the MP3 audio file is not set, and the above decryption key detection process and encryption decryption process are omitted. By using the decoding program, the compressed audio data is restored to the original audio data and immediately outputted to the audio signal processor 30.                     

Therefore, only a playback device such as an MP3 player equipped with an algorithm for detecting and combining the decryption key from the header information as described above can reproduce and output the encrypted MP3 audio file as normal high-quality audio data.

As described above, preferred embodiments of the present invention are disclosed for purposes of illustration, and the encryption and decryption process may be performed by various encryption methods such as a Read Solomon method. The detailed description thereof will be omitted, and the present invention is also applicable to other compressed audio files other than the MP3 audio file, and the present invention is provided within the technical scope and technical scope of the present invention disclosed in the appended claims. Various other embodiments may be improved, changed, replaced or added.

The encryption decryption key recording and reproducing method of the compressed audio file according to the present invention constructed and constructed as described above distributes and encrypts the encryption decryption key for the MP3 audio file encrypted for the purpose of copyright protection in the header information of the MP3 audio file. In addition, in a playback device such as an MP3 player, a producer in a process of encrypting and recording an MP3 audio file by detecting and combining a decryption key recorded in the header information and decrypting and restoring and reproducing the encrypted audio data. Does not need to store unique decryption keys arbitrarily designated and used in a playback device such as an MP3 player, and in a general playback device that does not include an algorithm for detecting and combining the decryption key recorded in the header information. For protection, encrypted MP3 audio files It is extremely useful that the inventors that a reproduction makes it possible to prevent,

Claims (9)

In a method for encrypting compressed data comprising a plurality of header parts and a frame part, Encrypting the compressed data with an encryption key; Generating a plurality of header parts for distributing and recording the encryption key; And And distributing and recording an encryption key in the plurality of additionally generated header parts. The method of claim 1, And the encryption key is distributed and recorded in specific areas of the plurality of additionally generated header parts. The method of claim 1, In the second step, a plurality of frame parts are additionally generated together with the plurality of header parts, and the additional information about compressed data is recorded in the frame parts. The method of claim 1, And a plurality of additionally generated headers that include information indicating whether to encrypt or not to be encrypted. The method of claim 1, And information for notifying how many headers the encryption key is distributed and recorded in tag information. In the method for decrypting the encrypted compressed data consisting of a plurality of header portion and the frame portion, Extracting encryption key values distributed and recorded in the plurality of headers, respectively; Combining the extracted encryption key values with each other to complete an encryption key; And And decrypting the encrypted compressed data using the encryption key. 3. The method of claim 6, And retrieving and confirming, from the tag information of the compressed audio file, how many headers the encryption key is distributed and recorded. The method of claim 6, And the encryption key value is distributed and recorded in specific areas of the plurality of header portions.  The method of claim 6, And an information indicating whether or not encryption is recorded in the plurality of header parts, respectively.

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