Abstract:
The present invention provides a digital sound recording device that prevents data stored as digital sound data from being forged. A digital sound recording device according to the present invention includes an input unit, a storage unit, a data communication unit, a processor, and a write protection unit that is provided between the storage unit and the data communication unit, thereby preventing the write control from being performed on the storage unit by the external unit.

Description:
RELATED APPLICATIONS 
       [0001]    The present application claims priority to Korean Patent Application Serial Number 10-2007-0124800, filed on Dec. 4, 2007, the entirety of which is hereby incorporated by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a digital sound recording device, such as a digital sound recorder, a mobile phone, and a wireless telephone, that records sound as digital data and includes additional units to prevent sound record from being forged, thereby improving admissibility of evidence. 
         [0004]    This work was supported by the IT R&amp;D program of MIC/IITA [2007-S-019-01, Development of Digital Forensic System for Information Transparency]. 
         [0005]    2. Description of the Related Art 
         [0006]    A digital sound recording device is a device for storing human voice or sound as digital files, and is referred to as a digital sound recorder, a voice recorder, or the like. The digital sound recording device also includes different devices, which are provided with a recording unit, such as a mobile phone and a wireless telephone. 
         [0007]    When there is a legal argument about a specific case, recorded data is submitted to the court as evidence in order to prove whether facts of the case are present or not. Recorded data is used as advantageous evidence. In this case, a digital sound recording device is widely used. 
         [0008]    However, since the recorded data of the digital sound recording device is also digital data, it is not free from forgery. 
         [0009]    In particular, in recent years, digital files are very easily edited using a computer, and sound data can be realistically modified and composed using excellent programs so that it is not possible to discriminate whether the data is forged. For this reason, it is difficult to prove that the recorded digital data is original data without forgery. 
       SUMMARY OF THE INVENTION 
       [0010]    Accordingly, it is an object of the present invention to provide a device that additionally includes specific circuits or programs in addition to a digital sound recording device to protect digital sound record from forgery and to confirm whether the data is genuine, and a method using the device. 
         [0011]    In order to achieve the above-mentioned object, according to an embodiment of the present invention, a digital sound recording device includes a sound input unit, a storage unit, a data communication unit, a processor, and a write protection unit. Sound is input to the sound input unit. The storage unit stores the input sound as digital sound data. The data communication unit performs data communication with an external unit. The processor controls the storage unit so that the sound input from the sound input unit is stored in the storage unit as digital sound data, and controls the data communication unit so that the digital sound data stored in the storage unit is transmitted and received to/from the external unit through the data communication unit. The write protection unit is provided between the storage unit and the data communication unit. The write protection unit prevents the write control from being performed on the storage unit by the external unit. 
         [0012]    Further, the digital sound recording device may further include a MAC (message authentication code) generator. When digital sound data is stored in the storage unit, the MAC generator generates a MAC corresponding to the digital sound data and stores the MAC in the storage unit. 
         [0013]    Furthermore, the MAC may be generated on the basis of a hardware identifier of the digital sound recording device. 
         [0014]    Furthermore, the MAC is incorporated in the corresponding digital sound data. 
         [0015]    In order to achieve the above-mentioned object, according to another embodiment of the present invention, a digital sound recording device includes a sound input unit, a storage unit, a data communication unit, a processor, and a MAC (message authentication code) generator. Sound is input to the sound input unit. The storage unit stores the input sound as digital sound data. The data communication unit performs data communication with an external unit. The processor controls the storage unit so that the sound input from the sound input unit is stored in the storage unit as digital sound data, and controls the data communication unit so that the digital sound data stored in the storage unit is transmitted and received to/from the external unit through the data communication unit. When digital sound data is stored in the storage unit, the MAC generator generates a MAC corresponding to the digital sound data and stores the MAC in the storage unit. 
         [0016]    Further, the MAC may be generated on the basis of a hardware identifier of the digital sound recording device. 
         [0017]    In the case of a digital sound recording device having credibility in respects to improved admissibility of evidence, data cannot be fabricated outside due to a write protection unit. Accordingly, when the sound recording device is produced as evidence, there may be free from the controversy about the forgery of recorded data. Further, when the recorded data stored in the storage unit is utilized outside the device, it is possible to prove that the data is identical with original data stored in the digital sound recording device by using message authentication codes. Therefore, the digital sound recording device can be used for various purposes. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]      FIG. 1  is a block diagram of a digital sound recording device in the related art; 
           [0019]      FIG. 2  is a block diagram of a digital sound recording device according to an embodiment of the present invention; 
           [0020]      FIG. 3  is a block diagram of a digital sound recording device according to another embodiment of the present invention; and 
           [0021]      FIG. 4  is a block diagram of a digital sound recording device according to still another embodiment of the present invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0022]    Preferred embodiments of the present invention will be described with reference to accompanying drawings. 
         [0023]    First, the configuration of a general digital sound recording device, which is currently used, will be described with reference to  FIG. 1 . 
         [0024]    A digital sound recording device  100  includes a microphone  106 , an A/D converter  107 , a storage unit  112 , a D/A converter  109 , a voice output unit  110 , an input button/switch  101 , an I/O unit  102 , a controller  104 , a display unit  105 , a data communication unit  103 , and a processor  108 . The microphone  106  converts sound into an electrical signal. The A/D converter  107  converts the electrical signal into digital sound data. The storage unit  112  stores the converted digital sound data. The D/A converter  109  converts the stored digital sound data into an analog signal. The voice output unit  110  converts the analog signal into sound. The input button/switch  101  is operated by a user. The I/O unit  102  converts the operation of the button or switch into an electrical signal. The controller  104  controls the screen of an LCD and the like. The display unit  105  is controlled by the controller and displays images, letters, and the like. The data communication unit  103  performs data communication with an external computer. The processor  108  controls the above-mentioned components of the digital sound recording device. 
         [0025]    A user begins to perform recording by operating the input button/switch  101 , and human voice or sound is stored in the storage unit  112  through the microphone  106 , the A/D converter  107 , and the processor  108 . In this case, the processor  108  may store the digital sound data, which is converted by the A/D converter, in the storage unit  112  as it is. Alternatively, the processor may compress the digital sound data by compression algorithm, and then store the compressed data in the storage unit  112  to use efficiently the storage unit. The user can confirm the progress of the recording, the size of the recorded sound data, and the number of recorded files by using the display unit  105 . The user can select specific sound data to confirm the recorded sound by using the display unit  105  and the input button/switch  101 . The processor  108  reads the selected digital sound data from the storage unit  112 , and controls the D/A converter  109  so that the selected digital sound data is converted into an analog signal. The voice output unit  110  converts the analog signal into audible sound. 
         [0026]    Further, the digital sound recording device  100  may further include a data communication unit  103 . The data communication unit allows the digital sound recording device to communicate with an external computer  111  so that the digital sound data can be utilized outside the device. Accordingly, the digital sound data stored in the storage unit  112  can be transmitted to an external unit, for example, the computer Ill by the data communication unit. Further, digital sound data stored in the external unit can be transmitted to the storage unit  112  by the data communication unit, and then stored in the storage unit. When the digital sound recording device communicates with the computer  111  as described above, it is possible to delete or store the sound data stored in the storage unit  112 . When this sound data is produced in a trial as evidence, there may be controversy about the forgery of the sound data. 
         [0027]    A digital sound recording device  200  according to an embodiment of the present invention will be described with reference to  FIG. 2 . The digital sound recording device  200  has the configuration similar to the general digital sound recording device  100 . However, the digital sound recording device  200  further includes a write protection unit  213  that is provided between a computer  211 , that is, an external unit and a storage unit  212 , which is different from the general digital sound recording device  100 . The write protection unit  213  functions to interrupt deletion and storage instructions from the external computer  211 , and functions to admit only a read instruction. The write protection unit may be composed of an electronic circuit. Alternatively, the write protection unit may be composed of a program code that is executed in a processor  208  or other processors different from the processor  208 . 
         [0028]    When digital sound data stored in the storage unit  212  is transmitted to the computer  211 , the digital sound data stored in the storage unit  212  is transmitted to the computer  211  through the processor  208  and a data communication unit  203 . Since this operation corresponds to “read” in the position of the computer  211 , the write protection unit  213  admits this operation. 
         [0029]    However, when the digital sound data is stored in the storage unit  212  from the computer  211 , the digital sound data transmitted through the data communication unit  203  and the write protection unit  213  recognizes this operation as “store”. Therefore, the write protection unit  213  interrupts that the digital sound data is stored in the storage unit  212  from the computer  211 . Further, the write protection unit  213  may interrupt a “delete” instruction from the external unit. For this reason, the digital sound data stored in the storage unit  212  can be protected from the access of the computer  211 . 
         [0030]    Accordingly, the digital sound data, which is fabricated outside the device, cannot be stored in the write protected digital sound recording device  200 . Therefore, when the digital sound data stored in the digital sound recording device  200  is produced as evidence, it is possible to prove that this digital sound data is not fabricated. 
         [0031]    Another embodiment of the present invention will be described with reference to  FIG. 3 . A digital sound recording device  300  shown in  FIG. 3  further includes a MAC (message authentication code) generator  314 , which is provided between a processor  308  and a storage unit  312 , in addition to the components of the general digital sound recording device. 
         [0032]    A MAC means an authentication code, which is used to confirm whether messages are changed or credible in order to prove the integrity of the messages. In general, a MAC value of a specific message m (that is, MAC=H(K, m)) is generated using a private key K and MAC generation algorithm H. If the message has been changed, a MAC value of the changed message does not correspond to an existing MAC value. Therefore, it is possible to easily verify that the message has been changed. Further, since it is not possible to restore the message from the MAC value, it is possible to easily and credibly prove the integrity of the message. 
         [0033]    Referring to  FIG. 3 , the MAC generator  314  generates authentication codes of all of the specific digital sound data. A block cipher or hash function, which has been already tested, is preferably used as the MAC generation algorithm. A key, which is known only to a maker, is preferably used as the private key. For example, a value, which has an eigenvalue such as a hardware identifier of the digital sound recording device  300  and is known only to a maker, may be used as the key. When an external user intends to fabricate recorded data stored in the storage unit  312  or to generate a message authentication code of not data recorded by the digital sound recording device  300  but data recorded by another device, only an authentication code different from the message authentication code capable of being generated from the digital sound recording device  300  is generated because the external user cannot know the key. Therefore, it is possible to confirm whether the data is genuine, by comparing the codes. 
         [0034]    The MAC generated by the MAC generator  314  may be stored in the storage unit  312  as an additional item of the recorded digital sound data, or may be stored as an independent file different from the digital sound data. Further, the MAC can be encoded so that the MAC is associated with the digital sound data and the only the MAC cannot be extracted. 
         [0035]    When the digital sound data is generated using digital sound recording device  300 , the data fabricated externally is different from the original digital sound data in terms of a MAC value. Accordingly, it is possible to determine whether the data is identical with the original digital sound data, by simply comparing the MACs of both data. As a result, it is possible to easily and accurately determine whether the data is genuine. 
         [0036]    Still another embodiment of the present invention will be described with reference to  FIG. 4 . A digital sound recording device  400  shown in  FIG. 4  further includes a write protection unit  413  that is provided between a computer  411  and a storage unit  412 , and a MAC generator  414  that is provided between a processor  408  and the storage unit  412 , in addition to the components of the general digital sound recording device  100 . 
         [0037]    The write protection unit  413  has the same function as the write protection unit  213  of  FIG. 2 . That is, the write protection unit prevents the digital sound data, which is transmitted from an external computer  411 , from being stored in the storage unit. Further, the write protection unit prevents the digital sound data, which is stored in the storage unit, from being changed by the computer  411 . 
         [0038]    In addition, a MAC generator  414  generates a MAC of the digital sound data to be stored in the storage unit. As described above, the MAC may be added to the digital sound data, separately stored, or associated with the digital sound data in the encoded form. 
         [0039]    When the digital sound recording device  400  is used, the digital sound data fabricated externally cannot be stored in the digital sound recording device. Therefore, when the digital sound data stored in the digital sound recording device  400  is produced as evidence, it is possible to prove that this digital sound data is not fabricated. Further, since the data fabricated outside the device has a MAC value different from that of the original digital sound data, it is possible to forge the digital sound data outside the device. Furthermore, it is possible to determine whether the data is identical with the original digital sound data, through the simple comparison between the MAC values of data. As a result, it is possible to easily and accurately determine whether the data is genuine. 
         [0040]    The digital sound recording device according to the present invention is not limited to the above-mentioned embodiments, and may be modified in various ways without departing from the scope of the present invention. The external units mentioned as the computers  211 ,  311 , and  411  may be other kinds of units that are connected to the digital sound recording device outside the device. As long as a digital sound recording device has the above-mentioned characteristic configuration, a process for recording and playing back digital sound data in the digital sound recording device may be modified in various ways. The write protection unit can prevent the writing by using hardware or programs.