KR20210087353A - System and Method for encryption/decription and channel-coding - Google Patents

Abstract

As a preferred embodiment of the present invention, a system for allowing a receiving unit to receive data transmitted from a transmitting unit comprises a transmitting unit which determines an encryption block size based on channel state information, separates data by a determined encryption block size unit, inputs an input value, Q^eM, generated based on the data separated by the encryption block size unit, to a channel encoding unit and an encryption unit, performs both turbo encoding and AES encryption, respectively, generates the entire ciphertext obtained by encrypting the data, and transmits it to a receiving end.

Description

Method and system for performing encryption/decryption and channel coding on data {System and Method for encryption/decryption and channel-coding}

The present invention relates to an encryption method used in a transmission/reception system.

As improved satellite networks provide users with a variety of data, it is becoming important to obtain data security performance using encryption on satellite channels. However, since the encryption technology is vulnerable to bit errors occurring in the wireless channel due to the avalanche effect, a stronger encryption technology for data confidentiality is required.

KR 10-1852526 KR 10-1227029 KR 10-2017-0023302 A

In a preferred embodiment of the present invention, encryption and channel coding are simultaneously performed in a transmission/reception system to increase data confidentiality, and to improve bit error rate (BER) and processing time.

As a preferred embodiment of the present invention, in a system for receiving data transmitted from a transmitting end at a receiving end, the method for performing encryption and channel coding on the data at the transmitting end includes separating the data into an encryption block size unit at the transmitting end step; _{inputting an input value Q M} generated based on the data separated in units of the encryption block size to a channel coding unit and an encryption unit; And _{based on the input value Q M} , the channel coding unit and the encryption unit perform turbo and performing encoding and AES encryption at the same time.

In a preferred embodiment of the present invention, the turbo encoding and the AES encryption are performed simultaneously in a cipher feedback (CFB) mode.

_{As a preferred embodiment of the present invention, the AES encryption is performed on the input value Q M} input to the encryption unit using a first encryption key, and the input input to the channel coding unit is performed using a second encryption key. It is characterized in that channel encoding is performed on the value Q _{M .}

As a preferred embodiment of the present invention, the input value Q _M is input to the channel coding unit of the current block and is simultaneously input to the encryption unit of the next block through a shift register. In this case, the current block processes M-th data among the data separated by the encryption block size unit, and the next block processes (M+1)-th data to perform parallel operation.

As a preferred embodiment of the present invention, the turbo encoding and the AES encryption are simultaneously performed on each of the data separated by the encryption block size unit. In this case, each data divided by the encryption block size unit uses a shift register. to be processed in parallel.

As a preferred embodiment of the present invention, the encryption block size is changed according to the channel state information.

As a preferred embodiment of the present invention, the channel coding unit changes the code rate during turbo encoding according to the channel state information.

As a preferred embodiment of the present invention, the encryption unit selects a bit corresponding to the encryption block size, and the remaining bits that are not selected are moved through a shift register.

As another preferred embodiment of the present invention, as a method of performing decryption and channel decoding on the data at the receiving end of a system for receiving data transmitted from the transmitting end at the receiving end, the receiving end receives the ciphertext, and the received ciphertext separating into units of encryption block size; _{inputting an input value Q M} generated based on the ciphertext separated in units of the encryption block size to a channel decoding unit and a decoding unit; And _{based on the input value Q M} , the channel coding unit and the encryption unit each turbo and simultaneously performing decoding and AES decoding.

을 채널인코딩부와 암호화부에 입력하여 각각 터보 인코딩 및 AES암호화를 동시에 수행하여 상기 데이터를 암호화한 전체 암호문을 생성하여 상기 수신단에 송신하는 송신부를 포함하는 것을 특징으로 한다. As another preferred embodiment of the present invention, the system for receiving the data transmitted from the transmitter by the receiver determines the encryption block size based on the channel state information, separates the data by the determined encryption block size unit, and blocks the encryption block Input value generated based on data separated by size unit

is input to the channel encoding unit and the encryption unit, respectively, performing turbo encoding and AES encryption at the same time to generate an entire ciphertext obtained by encrypting the data, and transmitting it to the receiving end.

을 채널디코딩부와 복호화부에 입력하여 각각 터보 디코딩 및 AES복호화를 동시에 수행하여 상기 전체 암호문을 전체 평문으로 복호화하는 수신부;를 포함하는 것을 특징으로 한다.As another preferred embodiment of the present invention, the system for receiving the data transmitted from the transmitting end at the receiving end receives the entire ciphertext obtained by encrypting the data, and separates the entire ciphertext according to the encryption block size determined based on the channel state information. and an input value generated based on each cipher text separated by the encryption block size unit.

is input to the channel decoding unit and the decoding unit to perform turbo decoding and AES decoding respectively, respectively, and a receiving unit for decoding the entire cipher text into the entire plain text.

배 높은 보안 성능을 얻고 적에게 모호성을 제공하는 효과가 있다. .The CFB-AES-TURBO method presented in a preferred embodiment of the present invention performs encryption and decryption by adjusting the cipher block length and code rate of the system according to the channel state information, thereby obtaining a processing time gain and a 10dB coding gain. It has the effect of improving the error rate. Also,

It has the effect of gaining twice the security performance and providing ambiguity to the enemy. .

1 shows an example of a satellite network in which a transmission/reception system is implemented as a preferred embodiment of the present invention.
2 is a diagram illustrating an internal configuration of a transmission/reception system as a preferred embodiment of the present invention.
3 to 4 show an example of using the CFB-AES-TURBO super-encryption technique in each of the transmitting end and the receiving end shown in FIG. 2 .
5 is a flowchart for simultaneously performing AES encryption and turbo encoding at the transmitting end as a preferred embodiment of the present invention.

Since the present invention can have various changes and can have various embodiments, specific embodiments are illustrated in the drawings and will be described in detail through the detailed description. However, this is not intended to limit the present invention to specific embodiments, and it should be understood that the present invention includes all modifications, equivalents and substitutes included in the spirit and scope of the present invention.

Hereinafter, exemplary embodiments according to the technical spirit of the present invention will be described with reference to the drawings.

1 shows an example of a satellite network 100 in which a transmission/reception system is implemented as a preferred embodiment of the present invention. Satellite networks are used in a variety of terminals including airplanes, ships, automobiles, mobile devices, broadcasting TV and audio, and the like.

In the case of a satellite network, data security is weaker than that of a terrestrial network, and there are also problems in latency and physical layer attacks. In a preferred embodiment of the present invention, an encryption technique capable of enhancing data security even in a satellite network is proposed.

In a preferred embodiment of the present invention, a terrestrial base station, a public key generator (PKG), and a satellite exchange parameters for encryption key exchange for a secure link. In a preferred embodiment of the present invention, the encryption key may use the first encryption key K1 used for AES encryption and the second encryption key K2 used for turbo encoding as disclosed in the embodiment shown in FIG. 3 .

As a preferred embodiment of the present invention, an exchange between the encryption key pair (K1, K2) together with the parameters received from the PKG can be performed between the satellite and the receiving end. The receiving end includes a gateway, a base station, another satellite, an aircraft, and the like.

2 is a diagram illustrating an internal configuration of a transmission/reception system as a preferred embodiment of the present invention. 3 to 4 show an example of using the CFB-AES-TURBO super-encryption technique in each of the transmitting end and the receiving end shown in FIG. 2 .

As a preferred embodiment of the present invention, the transmission/reception system 200 includes transmitting terminals 210 and 220 and receiving terminals 230 and 240 . In addition, the transmitters 210 and 220 and the receivers 230 and 240 can enhance data security even in a satellite network by using the CFB-AES-TURBO super-encryption technique.

To this end, the transmitters 210 and 220 simultaneously perform Advanced Encryption Standard (AES) encryption and turbo encoding as in the embodiment of FIG. 3 ( FIGS. 3 , 315 and 332 ). In this case, AES encryption is performed in cipher feedback (CFB) mode. As another preferred embodiment of the present invention, the transmitters 210 and 220 may simultaneously perform turbo encoding ( FIGS. 3 and 315 ) in the physical layer and AES ( FIGS. 3 and 332 ) encryption in a layer higher than the physical layer. .

Similarly, the receiving terminals 230 and 240 simultaneously perform AES (Advanced Encryption Standard) decoding and turbo decoding as in the embodiment of FIG. 4 . In this case, AES decoding is performed in CFB mode. As another preferred embodiment of the present invention, the receiving terminals 230 and 240 may simultaneously perform turbo decoding ( FIGS. 4 and 415 ) in the physical layer and AES decoding ( FIGS. 4 and 422 ) in a layer higher than the physical layer. .

Here, AES is a type of block encryption protocol, and CFB is an example of various operation modes used in the block encryption protocol. In a preferred embodiment of the present invention, real-time stream encryption is possible by implementing AES under CFB mode, and both bit protection and error correction are possible.

As a preferred embodiment of the present invention described above, it should be noted that the super-encryption technique of the transmission/reception system 200 and the CFB-AES-TURBO method is not only implemented in the satellite network, but can be implemented in various types of networks. .

As a preferred embodiment of the present invention, the transmission/reception system 200 may further include a channel state estimation unit 250 , a code rate determination unit 260 , and an encryption block size determination unit 270 .

The channel state estimator 250 generates channel state information of a radio channel. The channel state information includes weather information, noise level information of a wireless channel, the number of terminals transmitting and receiving data, distribution information, QoS information, and the like. In another embodiment of the present invention, the channel state estimator 250 may be installed in the transmitters 210 and 220 or the receivers 230 and 240, and when using the channel state information of the transmitters 210 and 220, CSIT (Channel) State Information Transmitter), and when channel state information of the receivers 230 and 240 is used, it can be classified as a Channel State Information Receiver (CSIR).

The channel state estimator 250 measures information on the state of a channel through which data communication is performed in a predetermined time period or aperiodically, and periodically or aperiodically or aperiodically transmits the measured channel state information to the channel coding unit and the encryption unit of the transmitting end. 210 , and may transmit to the channel coding unit and decoding unit 240 of the receiving end. In this case, the transmitting end or the receiving end may determine whether data can be smoothly transmitted through the wireless channel according to the channel state information.

As a preferred embodiment of the present invention, the transmission/reception system 200 may be implemented so that the transmitting terminals 230 and 240 receive feedback of channel state information of past channels from the receiving terminals 210 and 220 . In this case, the channel state estimator 250 generates the channel state information CSI based on the channel state information of the past channels fed back from the receivers 210 and 220 and the channel state information estimated for the current channel.

The code rate determiner 260 and the encryption block size determiner 270 determine a code rate and an encryption block size based on the channel state information CSI generated by the channel state estimation unit 250 .

The code rate represents a ratio indicating how much actual information bits can be included when data is encrypted. In other words, it means a value obtained by dividing the actual information bit length by the length of the encrypted data. The higher the code rate, the higher the average amount of information that can be carried per encrypted symbol.

The turbo encoding unit 210 and the turbo decoding unit 240 may perform channel coding based on a code rate, respectively. In this case, the code rate may be set so that the better the channel state, the higher the code rate. In a preferred embodiment of the present invention, since AES encryption and turbo encoding are simultaneously performed at the transmitting end, and AES decryption and turbo decoding are simultaneously performed at the receiving end, data is encrypted even when the code rate is close to 1. It works.

Encryption block size may be used to determine the length of each block prior to encryption and channel coding by dividing data to be transmitted in block units. As the length of the encryption block increases, the amount of actual information data that can be transmitted through one block may increase.

Based on the channel state information CSI, the better the channel state, the longer the encryption block size, and the worse the channel state, the shorter the encryption block size.

(300a)만큼의 평문데이터를 선택하는 과정을 반복한다. 이 경우, 송신단에서 수신단으로 전송하고자 하는 평문데이터 중 선택된

(300a) 길이에 대응하는 평문데이터(131)를 제외한 나머지 데이터는 쉬프트레지스터(321)를 통해 다음 블록(320)에서 사용된다. The transmitters 230 and 240 separate data to be transmitted to the receiver in units of encryption block size. Alternatively, the transmitting end (230,240) is an encryption block size in the plaintext data to be transmitted to the receiving end.

The process of selecting as many plaintext data as (300a) is repeated. In this case, the selected plaintext data to be transmitted from the transmitting end to the receiving end is selected.

Data other than the plaintext data 131 corresponding to the length 300a is used in the next block 320 through the shift register 321 .

In this process, when the encryption block size becomes longer, the number of plaintext blocks Plaintext1, Plaintext2, ..., Plaintext _m (FIGS. 3, 313, 323,333) in which data to be transmitted is separated by the transmitting end 230,240 increases. As a result, the plaintext block from the transmitter (230,240) Plaintext1, Plaintext2, ... , Plaintext m ( 3, 313, 323,333) encryption block obtained by encrypting the respective door _{Ciphertext1, Ciphertext2, ..., Ciphertext m} ( Fig. 3, 316,326,336) the number of increases

Conversely, when the encryption block size is shortened, the number of plaintext blocks (FIGS. 3, 313, 323,333) in which data to be transmitted by the transmitting end (230,240) is separated and the number of corresponding encrypted text blocks (FIGS. .

Referring to FIG. 3 , the process of simultaneously performing AES encryption and channel coding in the AES encryption unit and the turbo encoding unit 210 of the transmitter shown in FIG. 2 will be described.

(300a)로 분리한다. 암호화블록사이즈

(300a)는 채널상태정보CSI값에 따라 가변적인 값을 지닌다. 예를 들어, 수신단으로 전송하고자 하는 데이터를 M개로 분리한 경우, 송신단에서는 M개로 분할된 데이터 각각을 각 블록(310,320)에서 병렬로 처리하도록 구현할 수 있다. As a preferred embodiment of the present invention, the transmitting end transmits data to be transmitted to the receiving end in units of encryption block size.

(300a). Encryption block size

300a has a variable value according to the channel state information CSI value. For example, when M data to be transmitted to the receiving end is divided into M pieces, the transmitting end may be implemented such that each of the M divided data is processed in parallel in each block 310 and 320 .

M = data amount/encryption block size

In this case, M is a natural number and has a variable value depending on the amount of data to be transmitted from the transmitting end to the receiving end or the size of the encryption block.

는 아래와 같이 결정될 수 있다. In more detail, encryption block size

can be determined as follows.

In this case, N _k represents an encryption block size, Rk represents a transmission rate, Pk represents an uncoded BER, and W represents a window size. Sreq represents a security level whose maximum value is Smax. Nmax represents the maximum allowable encryption block size in 128 bits supported by AES encryption.

In consideration of the above, the optimal encryption block size can be expressed as follows, and in a preferred embodiment of the present invention, the transmitting end and the receiving end can use the optimal encryption block size value as the encryption block size value.

In this case, L indicates the window size and indicates how many channel state information is to be used. For example, when L=10, nine pieces of over- and under-channel state information may be used, and one may use an estimate Pk obtained by estimating channel state information of the current channel.

In a preferred embodiment of the present invention, a shift register 321 may be further included to process each of the divided data in parallel.

Referring to FIG. 3 , the first data Plaintext1 313 divided into M pieces may be processed in the first block 310 , and the second data Plaintext2 323 may be processed in the second block 320 . In the first block 310 of the transmitting end, Plaintext1 is encrypted with Ciphertext1(316), and in the second block 320, Plaintext2(323) is encrypted with Ciphertext1(326), thereby generating a total of M ciphertext Ciphertexts.

에 대응하는 비트와 Plaintext1(313)과 XOR연산이 이루어진다. Plaintext1(313)은 암호화블락사이즈

단위로 분할된 데이터를 나타낸다. 그리고, 선택되지 않은 나머지 비트는 쉬프트레지스터를 통해 다음 블록(320)으로 이동될 수 있다. Referring again to FIG. 3 , the transmitter performs an XOR operation on the result of performing AES encryption 312 using the initial value IV 311 and the first encryption key K1 312a and Plaintext1 313 . In this case, the encryption block size among 128-bit data in the AES encryption process

An XOR operation is performed with the corresponding bit and Plaintext1 (313). Plaintext1 (313) is the encryption block size.

Represents data divided into units. In addition, the remaining unselected bits may be moved to the next block 320 through the shift register.

(314)은 제1 블록(310)의 채널코딩부(315)와 제 2 블록(320)의 암호화부(322)에 동시에 입력된다. XOR operation value of the first block 310

314 is simultaneously input to the channel coding unit 315 of the first block 310 and the encryption unit 322 of the second block 320 .

은 제 2 암호화키 K2를 이용하여 채널인코딩되고, 동시에 제 2 블록(320)의 암호화부(322)에 입력된

은 제 1 암호화키 K1(322a)을 이용하여 AES암호화가 수행된다. Thereafter, the input to the channel coding unit 315 of the first block 310 is

is channel-encoded using the second encryption key K2, and is simultaneously input to the encryption unit 322 of the second block 320.

AES encryption is performed using the first encryption key K1 (322a).

Similarly, in m blocks, ciphertexts Ciphertext1(316), Ciphertext2(326),..., Ciphertext for plaintext Plaintext1(313), Plaintext2(323),...Plaintext _{m(333) in the following manner, respectively produces m} (336). The transmitter merges the generated Ciphertext1(316), Ciphertext2(326),..., Ciphertext _m (336) into one and transmits it to the receiver. Accordingly, the transmitting end can generate the entire cipher text for the data to be transmitted to the receiving end.

은 AES암호화 및 터보인코딩 과정의 m 번째 쉬프트레지스터의 입력값을 나타내고,

는 m 번째 XOR연산 수행값을 나타낸다. E[K1,

]에서 E[]는 제 1 암호화키 K1을 이용하여 암호화한 결과값을 나타낸다. LSB 는 Least Significant Bit의 약자이고, MSB는 Most Significant Bit의 약자를 각각 나타낸다. in this case,

represents the input value of the m-th shift register of the AES encryption and turbo encoding process,

represents the value of the m-th XOR operation. E[K1,

], E[] represents the result of encryption using the first encryption key K1. LSB stands for Least Significant Bit, and MSB stands for Most Significant Bit.

FIG. 4 shows a process in which AES decoding and turbo decoding are performed at the receiving end as a preferred embodiment of the present invention, and is substantially similar to the process performed at the transmitting end of FIG. 3 .

The receiving end generates m plaintexts for m ciphertexts in the following manner in the m blocks 410 and 420 in the following manner. The receiving end may merge the m generated plaintexts into one to generate the entire plaintext for the entire ciphertext.

은 AES복호화 및 터보디코딩 과정의 m 번째 쉬프트레지스터의 입력값을 나타내고,

는 m 번째 터보디코딩의 결과값(415)을 나타낸다. 수신단에서는 암호키 교환 과정을 통해 암호화 키쌍(K1, K2)를 획득할 수 있다. 수신단에서도 AES복호화와 터보디코딩은 동시에 이루어진다. 즉, 송신단에서 이루어지는 AES암호화 및 터보인코딩 과정을 역으로 수행한다. in this case,

represents the input value of the m-th shift register of the AES decoding and turbo decoding process,

denotes a result value 415 of the m-th turbo decoding. The receiving end may acquire the encryption key pair (K1, K2) through the encryption key exchange process. At the receiving end, AES decoding and turbo decoding are performed simultaneously. That is, the AES encryption and turbo encoding processes performed at the transmitter are reversed.

5 is a flowchart for simultaneously performing AES encryption and turbo encoding at the transmitting end as a preferred embodiment of the present invention.

The data to be transmitted from the transmitting end to the receiving end is divided into units of encryption block size based on the channel state information (S510). When the channel state information is good, the encryption block size becomes large, and when the channel state information is bad, the encryption block size decreases. For the channel state information, a preset standard may be used, and for example, the standard may be set as having better channel state information than on a rainy day on a sunny day.

,

,...,

을 기초로 터보 인코딩 및 AES암호화를 동시에 수행한다(S520).Each input value generated based on each data separated by the encryption block size unit

,

,...,

Turbo encoding and AES encryption are simultaneously performed on the basis of (S520).

As mentioned above, although embodiments of the present invention have been described with reference to the accompanying drawings, those of ordinary skill in the art to which the present invention pertains can implement the present invention in other specific forms without changing its technical spirit or essential features. You can understand that there is Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive.

Claims (15)

A method of performing encryption and channel coding on the data at a transmitting end in a system for receiving data transmitted from a transmitting end at a receiving end, the method comprising:
separating the data into encryption block size units at the transmitting end;
_{inputting an input value Q M} generated based on the data separated into the encryption block size unit into a channel coding unit and an encryption unit; and
and simultaneously performing turbo encoding and AES encryption in the channel coding unit and the encryption unit, respectively, based on the input value Q _{M .} The method of claim 1, wherein the turbo encoding and the AES encryption are performed simultaneously in a cipher feedback (CFB) mode. The method of claim 1,
_{AES encryption is performed on the input value Q M} input to the encryption unit using a first encryption key, and channel encoding is performed _{on the input value Q M} input to the channel encoding unit using a second encryption key. A method characterized in that The method of claim 1,
The input value Q _M is input to the channel coding unit of the current block, and is also simultaneously input to the encryption unit of the next block through a shift register. 5. The method of claim 4,
The current block processes M-th data among the data separated by the encryption block size unit, and the next block processes (M+1)-th data to perform parallel operation. The method of claim 1,
The turbo encoding and the AES encryption are simultaneously performed on each of the data separated by the encryption block size unit, and in this case, each data divided by the encryption block size unit is processed in parallel using a shift register. How to. The method of claim 1,
A method characterized in that the encryption block size is changed according to the channel state information. The method of claim 1, wherein the channel coding unit
A method characterized in that the code rate is changed during the turbo encoding according to the channel state information. The method of claim 1, wherein the encryption unit
A method of selecting a bit corresponding to the encryption block size, and moving the remaining bits that are not selected through a shift register. A method of performing decoding and channel decoding on the data at a receiving end of a system for receiving data transmitted from a transmitting end at a receiving end, the method comprising:
receiving the cipher text at the receiving end, and separating the received cipher text into an encryption block size unit;
_{inputting an input value Q M} generated based on the cipher text separated by the encryption block size unit to a channel decoding unit and a decoding unit; and
and performing turbo decoding and AES decoding by the channel coding unit and the encryption unit at the same time, respectively, based on the input value Q _{M .} 11. The method of claim 10, wherein the turbo decoding and the AES decoding are performed simultaneously in a cipher feedback (CFB) mode. A system for receiving data transmitted from a transmitter by a receiver,
An input value generated based on determining the encryption block size based on the channel state information, separating the data by the determined unit of the encryption block size, and dividing the data by the unit of the encryption block size

is input to the channel encoding unit and the encryption unit, respectively, performing turbo encoding and AES encryption at the same time to generate an entire cipher text obtained by encrypting the data, and a transmitting unit for transmitting the generated cipher text to the receiving end. 13. The method of claim 12,
The turbo encoding is performed in a physical layer, and the AES encryption is performed in a higher layer than the physical layer. A system for receiving data transmitted from a transmitting end at a receiving end,
Receives the entire ciphertext obtained by encrypting the data, separates the entire ciphertext according to the encryption block size determined based on the channel state information, and an input value generated based on each ciphertext separated by the encryption block size unit

is input to the channel decoding unit and the decoding unit to perform turbo decoding and AES decoding respectively, respectively, and a receiving unit for decoding the entire ciphertext into the entire plaintext. 15. The method of claim 14,
The system according to claim 1, wherein the turbo decoding is performed in a physical layer, and the AES decoding is performed in a layer higher than the physical layer.

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