KR101000655B1 - A method and a device of coding payload data for gsm mobile phone - Google Patents

Abstract

The present invention is to partially encrypt the payload data of the SM type mobile terminal to quickly transmit it in a secure state, and to block the code to adjust the transmission speed appropriately for the line condition for transmitting the payload data. A code unit for easily convolutional code processing for error recovery; An encryption / decoding unit for encrypting a frame selected by the control signal among a plurality of frames of payload data applied from the code unit; An encryption control unit for outputting a control signal for partially selecting a frame encrypted among a plurality of frames of payload data by an encryption / decryption unit; Determining whether to transmit payload data to a communication counterpart; In case of transmitting payload data, selecting a specific frame to encrypt, and encrypting the selected frame; In the above process, the selected frame transmits the encrypted payload data and the frame selection signal together, thereby reducing the load on the system and increasing the transmission speed to perform real-time communication, improving communication quality and system reliability. In addition, it has the effect of enhancing the secretion function to secure the communication contents.

Description

Apparatus and method for encrypting payload data {A METHOD AND A DEVICE OF CODING PAYLOAD DATA FOR GSM MOBILE PHONE}

1 is an explanatory diagram of encryption / decryption processing of a general GSM mobile communication system;

2 is a functional configuration diagram of a payload data encryption transmission apparatus of a conventional GSM portable terminal;

3 is a flowchart illustrating a method for transmitting and receiving payload data encryption in a conventional mobile terminal.

4 is a functional block diagram of a payload data encryption transmission apparatus of a gsm mobile terminal of the present invention;

5 is a configuration diagram of a normal burst frame of a GSM mobile communication system;

6 is a flowchart illustrating a method for encrypting payload data of a gsm mobile terminal according to the present invention.

** Explanation of symbols on the main parts of the drawing **

100: code unit 110: encryption and decryption unit 120: encryption control unit

130: burst portion 140: compression portion 150: transceiver

The present invention encrypts and transmits payload data of a gsm mobile communication terminal, and in particular, payload data that is securely and quickly transmitted in a secure state by partially encrypting payload data that requires real-time transmission. The present invention relates to an encryption transmission apparatus and method.

The mobile communication system uses a registered mobile terminal (MS: MOBILE STATION), moves freely in the corresponding service area and communicates with the other party at any time and anywhere by wireless connection, and moves simultaneously using a limited radio frequency resource. The advanced technology for communicating is applied, and is classified into a code division multiple access (CDMA) method, a GSM method, and the like according to the use method of the limited frequency resources as described above.

The GSM (GLOBAL SYSTEM FOR MOBILE COMMUDMA: NICATION) mobile communication system uses a frequency division multiple access (F FREQUENCY DIVISION MULTIPLE ACCESS) scheme and a time division multiple access (TDMA) scheme. It is a mixed operation, and it is a digital mobile communication system that allows multiple subscribers (SUBSCRIBER) or mobile terminals (MS: MOBILE STATION or UE: USER EQUIPMENT) to simultaneously occupy the corresponding channel and communicate while moving. Standard operation method of selected mobile communication system.

In the mobile communication system as described above, mobile communication is performed by wirelessly transmitting and receiving various control signals and communication signals between a base station (BS) and a mobile terminal (MS), and various control signals are required for operation of the mobile communication system. Since the communication signal is data that the user USER pays and uses, the area in which the communication data necessary for the user's mobile terminal MS is loaded is called a user area or a payload area. Data carried in the area is referred to as user data or payload data.

Such user data or payload data should be delivered only to designated communication counterparts, i.e., must be kept confidential by non-communication communication, transmitted to a third party, or eavesdropped by a third party. In order to prevent this from happening, the transmitting side encrypts and transmits an encryption key (Kc: ENCRYPTION KEY) on a frame basis, and the receiving side performs decryption communication using the encryption key on a frame basis.

In the mobile communication system, there is a data level communication using a character and the like and a multimedia level communication using an image, while the multimedia level communication has a large amount of data. It takes time and at the same time increases the load of the system has been a relatively difficult real-time communication problem.

Accordingly, there is a need to develop a method of improving the reliability by real time communication by reducing the time for encrypting the multimedia signal and reducing the load on the system.

Hereinafter, according to the prior art, the encryption method of the payload data of the GSM mobile terminal will be described with reference to the accompanying drawings.

1 is an explanatory diagram of encryption / decryption processing of a general GSM mobile communication system, and FIG. 2 is a functional configuration diagram of a payload data encryption transmission apparatus of a conventional GSM mobile terminal. 3 is a flowchart illustrating a payload data encryption transmission method of a GSM mobile terminal according to the prior art.

Referring to FIG. 1, encryption and decryption processing of a general GSM mobile communication system includes a user data (USER DATA) 1 to be transmitted to a communication counterpart by a transmitting mobile terminal (MS) to the encryption unit (2). In addition, the control unit 3 which receives a frame number (FN: FRAME NUMBER) and an encryption key (Kc: ENCRYPTION KEY) of data to be transmitted generates an encryption key 4 by an A5 encryption algorithm to generate the encryption. Output to part (2).

The transmitting side encrypting unit 2 inputs user data 1 to be transmitted, is encrypted by an encryption key 4 applied from the control unit 3, and is encrypted as described above. And the frame number FN and the encryption key Kc are wirelessly transmitted to the other party in a synchronous state, and are received by the communication partner through the mobile communication system.

The receiving side receiving the encrypted signal processes the received signal to detect the frame number FN and the encryption key Kc, and applies the received signal to the receiving side controller 5, wherein the controller 5 uses the A5 scheme. The encryption key 6 is generated by the encryption algorithm processing and output to the decryption unit 7.

The transmitting side encryption key 4 and the receiving side encryption key 6 have the same value.                         

In addition, the receiving unit outputs the encrypted user data by processing the received signal to the decryption unit 7, and the decryption unit which inputs the encryption key 6 and the encrypted user data as described above is originally subjected to the corresponding decoding process. The user data 8 of 8 is extracted and output.

That is, the transmitting side generates an encryption key 4 and applies it to the encryption unit 2 by processing the encryption key input in units of frames of user data, and the encryption unit 2 transmits the user data 1. Is encrypted by the encryption key 4, and the encrypted user data together with the frame number FN and the encryption key Kc are transmitted to the counterpart in a synchronous state.

The receiving end recovers the encryption key 6 by A5 algorithm processing the frame number FN and the encryption key Kc from the received signal, and encrypts the received user data by the restored encryption key 6. The decrypted and restored user data 8 is output.

Hereinafter, with reference to the accompanying Figure 2, a description will be given of a payload data encryption transmission apparatus of a conventional mobile communication terminal of the SM method.

The current state of the corresponding communication line to which user data or payload data to be transmitted by the GSM mobile communication terminal (MS) is detected and transmitted at the most suitable transmission rate A code section that performs a block code that is periodically adjusted and a convolution code that minimizes data loss damage caused by a transmission error of the transmitted payload data, and vice versa. 10; An encryption / decryption unit 20 for encrypting or decrypting user data or payload data applied from the code unit 10 with an encryption key; A burst unit 30 suitable for formatting the payload data encrypted as described above in accordance with a dedicated burst format (BURST) format for transmission of the payload data of the SMS method or vice versa; A compression unit (40) for reducing the size of the encrypted data signal applied through the burst unit (30) or vice versa; It consists of a transceiver 50 for amplifying and transmitting a signal applied from the compression unit 40 to a predetermined level or vice versa.

Hereinafter, an apparatus for encrypting payload data of a GSM mobile terminal according to the related art having the above configuration will be described in detail with reference to the accompanying drawings.

When the transmitting side of the GSM mobile terminal MS applies the user data or payload data signal to the communication counterpart to the code unit 10, the current of the transmission line is determined by a block code. Set the transmission speed that can be transmitted fastest in the state, set the transmission speed of the current frame data, and encode and transmit by the convolutional code so that the receiver can easily recover even if a transmission error occurs. do.

The user data or payload data signal, which is encoded and output so that the transmission speed is adjusted in the code unit 10 and is easily restored, is applied to the encryption / decryption unit 20 and is encrypted and output with the corresponding encryption key. The burst unit Since the digital code signal is applied to 30 and formatted in a standard burst format, and the user code or payload data applied to the compression unit 40 and overlapped in a continuous state is represented by a corresponding code. Compresses and outputs the differential code method to reduce the total amount of data, and the user data or payload data signal output from the compression unit 40 is applied to the transceiver unit 50, amplified to a predetermined level, and applied to the corresponding antenna. And is wirelessly output to the communication counterpart through the mobile communication system.

When the communication counterpart receives the signal, it is processed in the reverse order, so that the encrypted user data or payload data is decrypted, and the original communication signal is recovered to perform communication.

Hereinafter, a payload data encryption transmission method of a conventional GSM mobile terminal will be described with reference to the accompanying drawings.

A first step (S10) of determining whether to transmit user data or payload data by the transmitting side of the portable terminal; A second step (S20) of encrypting the payload data for transmission as a whole when the payload data is determined in the step; A third step (S30) of wirelessly transmitting the payload data encrypted in the step and transmitting it to the communication partner; A fourth step S40 of determining whether to receive payload data of the user; In operation S50, the payload data is decrypted when the user data is determined based on the determination.

Hereinafter, according to the prior art of the configuration described above, when the payload data encryption transmission method of the GSM mobile terminal is described, it is determined whether to transmit user data or payload data by the transmitting side of the mobile terminal (S10). In the case of the transmission in the determination, all frames of the user payload data are encrypted (S20) and up-modulated to the corresponding high frequency signal and transmitted (S30).

In addition, when determining that the mobile terminal receives the payload data of the user (S40), since both of the received payload data are decoded and the payload data of the user is recovered, the two-way communication proceeds.

However, the conventional user payload data encryption transmission as described above encrypts payload data of all frames transmitted and received. When the transmission bandwidth is wide and the amount of data transmitted and received is large, such as multimedia communication, encryption and decryption are performed. It takes a lot of time to increase the load of the mobile terminal and the mobile communication system.

In addition, since it takes a long time to encrypt and decrypt, there is a problem that a delay occurs in the transmission of a communication signal and a decrease in the communication quality reliability of the mobile communication system.

The present invention encrypts and transmits a part of a designated frame among a plurality of frames of payload data transmitted by a user, and decrypts the received side, thereby maintaining a secretion function and rapidly transmitting a multimedia communication signal while reducing the load of a mobile communication system. It is an object of the present invention to provide an apparatus and method for encrypting payload data.

The present invention has been made to achieve the above object, in the SM type mobile terminal; A code unit for easily adjusting a block code for adjusting a transmission speed and a convolutional code for error recovery according to a line state for transmitting the payload data to be transmitted; An encryption / decoding unit for encrypting a frame selected by a corresponding control signal among a plurality of frames of payload data applied from the code unit; An encryption control unit for outputting a control signal for partially selecting a frame encrypted among the plurality of frames of payload data by the encryption / decryption unit; And a burst unit for formatting and converting the payload data signal partially encrypted from the encryption / decryption unit into a corresponding format.

In addition, the present invention devised to achieve the above object comprises the steps of: determining whether to send payload data to the communication counterpart; A partial processing step of selecting a specific frame to encrypt and encrypting the selected frame when transmitting payload data; In the above process, the selected frame is characterized by consisting of transmitting the encrypted payload data and the frame selection signal together.

Hereinafter, an apparatus and method for encrypting payload data of a GSM mobile terminal according to the present invention will be described with reference to the accompanying drawings.

4 is a functional configuration diagram of a payload data encryption transmission apparatus of a GSM mobile terminal according to the present invention, and FIG. 5 is a configuration state of a normal burst frame of a GSM mobile communication system. 6 is a flowchart illustrating a payload data encryption transmission method of a GSM mobile terminal according to the present invention.                     

4, a payload data encryption transmission apparatus of a GSM mobile terminal will be described.

The SM type mobile terminal inputs communication data to be transmitted, checks a transmission speed capable of transmitting data most appropriately to a state of a communication line allocated by a block code, and sets the transmission speed to be transmitted at a corresponding transmission speed. A code unit 100 for encoding the transmitted user data or payload data in a convolution manner and processing a convolution code to facilitate recovery of a transmission error at a receiving side;

Encrypts a frame selected by a corresponding control signal among a plurality of frames of payload data applied from the code unit 100. The code unit may be encrypted by a control signal applied from an encryption controller 120 to be described later. A specific frame is selected and encrypted from among a plurality of frames of payload data applied from 100), and the encrypted state is assigned to the first byte (BYTE) consisting of 8 bits (BIT) in a data area including 57 data bits of frame data. An encryption / decoding unit (110) for recording encrypted state recognition data, and outputting a control signal applied from the encryption control unit (120) and the partially encrypted payload data together;

The encryption / decoding unit 110 outputs a control signal for partially selecting a frame to be encrypted from among a plurality of frames (FRAME) of payload data, and encrypts by selecting one or a plurality of frames from the frames constituting the payload data. And, the order of the plurality of selected frames are encrypted control unit 120 for outputting a control signal to be repeated irregularly,

A burst unit 130 for formatting and converting a payload data signal that is partially encrypted from the encryption / decryption unit 110 to a corresponding SM format;

A compression unit 140 which analyzes the signal applied from the burst unit 130 and compresses and outputs a code which is sequentially overlapped by separate coding, and simultaneously decompresses and outputs a signal applied in a compressed state;

Up-converts the signal applied from the compression unit 140 and transmits the received signal. The received signal is down-converted and output to the compression unit 140.

Hereinafter, the payload data encryption apparatus of the GSM mobile terminal according to the present invention having the above configuration will be described in detail with reference to the accompanying drawings.

The code unit 100 monitors a line state in which the payload data is transmitted by a block code, periodically checks a most suitable transmission rate at which the data is to be transmitted, and payload at the confirmed transmission rate. The data is set to be transmitted, and the 8-bit byte unit (BYTE) of the payload data to be transmitted is accumulated by overlapping the number of bytes by a convolution code, and the overlapped and accumulated byte unit data is accumulated. Reconstruct the vertical data corresponding to the same sequence number into each byte unit data and transmit it, and the receiver side receives and restores the original byte again. In the above case, the receiver side signal one byte unit due to a transmission error. Receive Side Bytes (BYTE) Actually Configured by Convolution Even When All Errors Occur Since an error in only one bit (BIT) occurs, so that the repair is easy.

In other words, if an error occurs in one byte unit while data is being transmitted normally, the receiver cannot correct the data in that byte unit. However, if the convolutional code method is used, one byte unit is used. Even if a transmission error occurs in the signal, there is a problem in that a transmission error caused by an error occurs by one bit in 8 byte units on the receiving side, but error correction is easy in each byte unit. As a result, all errors in 8-byte data can be corrected.

Payload data processed as a block code and a convolution code by the code unit 100 is applied to the encryption / decoding unit 110, and the encryption / decoding unit 110 is applied to the control signal of the encryption control unit 120. A specific frame is selected from a plurality of frames constituting payload data, and the data of the selected frame is encrypted by a controlled encryption key and outputted to the burst unit 130.

The encryption controller 120 may control the encryption / decryption unit 110 to select and encrypt one frame among a plurality of frames of payload data, may select and encrypt a plurality of frames, and configure payload data. Since some frames are encrypted instead of the entire frame, partial encryption is performed.

As described above, the order of a plurality of frames selected and encrypted by the encryption / decryption unit 110 under the control of the encryption control unit 120 is due to discontinuity, and the selection method may be various. For example, a random number check method may be used. The burst information 130 indicates that the information of the selected frame is transmitted to the receiving side so that the receiving side can confirm the information, and that the information is encrypted in the corresponding frame.

The burst unit 130 formats the payload data partially encrypted by the encryption / decryption unit 110 in a wireless transmission format of a GSM method, and formats it as a normal burst (NB).

The format of the GMS format is, for example, a normal burst (NB) format, a frequency correction burst (FB) format, a synchronization burst (SB: SYNCHRONIZATION BURST) format, and a dummy burst. (DB: DUMMY BURST) format, access burst (AB: ACCESS BURST) format, and the like, and payload data is formatted in the normal burst format.

The frame FRAME configuration state of the normal burst NB is shown in detail in FIG. 5. The first and last 3 bits are used as tail bits, and a logical value 0 is recorded. To indicate the start (START) and the end (END) of the frame (FRAME), and data for communication is recorded by the 57-bit traffic area in the order following the tail bit indicating the start. There is a signaling bit area indicating that the control signal of BIT starts, followed by a training sequence area for the 26-bit control signal, and again indicating that the control signal of 1 bit is finished. There is a signaling bit area, and a traffic area of 57 bits is configured.

In order to distinguish each of the plurality of NB frames as described above, the last 8.25 bits are allocated and the 8.25 bits do not transmit data, and are also used to distinguish the FB, SB, and DB frames. Allocate 68.25 bits to which no data is transmitted.

In the NB format configured as described above, information of a frame encrypted by the encryption control unit 120 is recorded, and one byte (BYTE) by 8 bits (BIT) of the preceding 57 bits (BIT) constituting the traffic area. Is assigned to indicate whether the data of the corresponding frame is encrypted or normal data, and the corresponding control signal is recorded in the 26-bit control region or training sequence region. Search and verify encrypted status.

As described above, the payload data converted from the burst unit 130 to the GS transmission format is applied to the compression unit 140 and compressed. The compression method is indicated by a corresponding symbol when logical values of the same state are continuous. As an example, when 0 is repeated five consecutive times as in 00000, it is recorded as a 0-5 symbol, and when 1 is repeated seven times as in 1111111, it is recorded as a 1-7 symbol. The compression method as described above is called differential coding (DIFFERENTIAL CODING).

As described above, the data compressed by the compression unit 140 and reduced in size or amount are applied to the transceiver 150 to be up-converted to the corresponding high-frequency signal of the SM method, and wirelessly transmitted through the antenna, and receiving the signal. The receiver performs the above processing in the reverse order to restore the payload data.

Therefore, the configuration according to the present invention does not encrypt all the multimedia data transmitted through the GSM mobile communication system, but encrypts and transmits the data of the selected part of the frame, so that the system can be quickly processed while maintaining the secretion function. It reduces the load of and increases the reliability by transmitting the communication signal quickly.

Below. With reference to the accompanying FIG. 6, the encryption transmission method of payload data will be described.

Determining whether to transmit payload data to a communication counterpart by a gsm mobile terminal (S100);

When the payload data is transmitted in the above process, a specific frame to be encrypted is selected, and the selected frame is encrypted, and a frame to be encrypted from among a plurality of frames of payload data is encrypted by the encryption controller 120 of the mobile terminal. Selecting one or more (S110); Partial processing consisting of the step (S120) of encrypting only the frame selected in the step (S110),

The frame selected in the partial processing transmits the encrypted payload data and the frame selection signal together, and records the encryption state in the first byte constituting the traffic region of the payload data, and encrypts the control unit 120 in the control region. In step S130, the control signal is recorded and transmitted together.

Hereinafter, a method of encrypting and transmitting payload data according to the present invention having the above configuration will be described in detail with reference to the accompanying drawings.

When communication with the other party is started using the GSM mobile terminal, the mobile terminal MS determines to transmit payload data (S100), and the payload data input by the user is determined. It is applied to the encryption and decryption unit 110 through the code unit 100, the encryption control unit 120 applies a corresponding control signal for selecting one or more frames to be encrypted to the encryption and decryption unit 110 (S110). .

The encryption / decryption unit 110, which receives a control signal for selecting a frame to encrypt from the encryption control unit 120 by the process (S110), encrypts data of a selected frame among a plurality of frames constituting payload data by an encryption key. Therefore, the payload data is partially encrypted (S120), and the partially encrypted payload data is output to the burst unit 130 as described above.

The burst unit 130 formats the partially encrypted payload data and the encrypted frame selection signal applied from the encryption control unit 120 into a normal burst (NB) format and transmits them to the counterpart through compression and upconversion. (S130).

The payload data transmitted as described above is received at the receiving side, and is processed by the reverse process described above, thereby recovering the communication.

Therefore, the data of some selected frames are encrypted without encrypting the entire payload data to be transmitted, so the processing time is fast, the load of the system is reduced, real time communication is performed, and the communication quality and reliability of the system are improved. There are advantages such as uplifting.

In addition, in encryption for a secret call, a method of randomly selecting a number and position of some frames among a plurality of frames in addition to the conventional method of using an encryption key (Kc) is added. Further increase has the advantage that the sparking performance is improved.

According to the present invention having the above configuration, since only a partial frame of payload data transmitted by the SM type mobile terminal is encrypted and transmitted, there is an industrial use effect of reducing the load on the system and increasing the transmission speed to perform real time communication.

In addition, since the load on the mobile communication system is reduced, there is a convenient effect in improving communication quality and system reliability.

In addition, since the number and position of the encrypted frame of the payload data are arbitrarily changed, the number of cases increases, which has a convenient effect on improving the performance of the non-functionality function for maintaining the security of communication contents.

Claims (10)

A block code for adjusting a transmission speed and a convolution code for easy convolution code processing in consideration of a line state for transmitting transmitted payload data; A control signal for outputting a control signal for selecting an encrypted frame among a plurality of frames of payload data applied from the code part, wherein the control signal has an irregularity such that the selection of the encrypted frame is irregular; , A specific frame is selected from among a plurality of frames of payload data applied from the code unit according to a control signal applied from the encryption controller, and the control signal applied from the encryption controller and the partially encrypted payload data are output together. With cancer decryption unit to say, And a burst unit for converting a signal output from the encryption / decryption unit into a format capable of wireless transmission. According to claim 1, A compression unit which analyzes a signal applied from the burst unit and compresses and outputs a code which is continuously overlapped by separate encoding, and decompresses and outputs a signal applied in a compressed state; And a transmission / reception unit for up-converting and transmitting the signal applied from the compression unit and down-converting the received signal. The method of claim 1, wherein the code unit, By monitoring the line state in which the payload data is transmitted by a block code and periodically checking and setting to optimize the transmission speed, By using a convolution code, the byte unit of payload data to be transmitted is accumulated by byte number, and the signal corresponding to the same sequence number of the overlapped accumulated byte unit data is reconstructed into each byte unit data and transmitted simultaneously. Encryption transmission apparatus of a mobile terminal, characterized in that the reverse processing. delete delete The method of claim 1, wherein the encryption and decoding unit, And transmitting the data received for encryption state recognition in the first byte of the data area of the payload data and simultaneously processing the received signal. Determining whether to send payload data to a communication counterpart; Generating a predetermined control signal having irregularities; A partial processing step of selecting and encrypting one or more frames from among a plurality of frames of payload data according to the control signal when transmitting the payload data; And transmitting and converting the encrypted payload data and the frame selection signal into a format that can be transmitted wirelessly. delete 8. The method of claim 7, The encrypted data transmission method of the payload data, characterized in that the frame is encrypted one or a plurality of discrete. The method of claim 7, wherein the transmitting process, And recording an encryption state in a first byte constituting a traffic region of the encrypted payload data, and transmitting a control signal of an encryption control unit in a control region and transmitting the encrypted signal together.

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