CN102571281B - A kind of secure network coding and transmission method and device that uses cache node - Google Patents

Abstract

The secure network coding method and the device that use cache node, specifically comprise: realize the confidentiality of network by encrypting information source information, realize the function of the integrity check of network by completeness check code. In source information encryption, only need to encrypt a part of information wherein and can realize the confidentiality function of network, indirect like this minimizing needs the information content encrypted. In device, intermediate node has caching function, and completeness check is to realize by the method that intermediate node is checked, intermediate node retransmits.

Description

A secure network coding transmission method and device using cache nodes

technical field

The present invention relates to the communication field, in particular to a method and device for secure network code transmission using cache nodes.

Background technique

In the current communication network, the role of intermediate nodes is mainly to store and forward, and it is difficult for the network to achieve the goal of maximum flow proposed by Shannon. This situation was not changed until the network coding was proposed. The original intention of network coding is to increase the maximum flow of the network, but it is found in the research process that network coding also has a very good prospect in terms of network security.

For the traditional multicast method, if an eavesdropper has the opportunity to eavesdrop on a certain channel of information in the network, it can restore the original data based on the eavesdropped information, because such information is "meaningful", and "meaningful" means eavesdropping The information sent by the source is the same as the information sent by the source. In the case of high security requirements, the anti-eavesdropping ability of traditional multicast is relatively weak; while in the data transmission method based on network coding, the coding nodes have different pairs of The function of mixing the information of the link, so as to change the "meaningful" information into "meaningless", this method makes the network coding have a certain degree of confidentiality, however, the eavesdropper is eavesdropping on the multi-channel information and After understanding the codec construction method of network coding, the original information can still be restored through the obtained multi-channel information; in addition, it is precisely because network coding can mix information, once the information on the upstream link is wrong or tampered with by other attackers Data, the information of the downstream link is likely to become wrong, which will increase the coverage of errors and have a bad impact on network information security. Therefore, when network coding is applied to network security, the confidentiality and integrity of information are particularly important.

There are many implementations of secure network coding, but these implementations still have the following problems: using cryptographic encryption to achieve network confidentiality, this method can achieve the effect of confidentiality, but the amount of encryption required is too large , a huge amount of calculation will be generated in the process of encryption and decryption; use non-encryption means to achieve confidentiality, this method needs to limit the eavesdropper's eavesdropping ability to certain links, for eavesdroppers with strong eavesdropping ability, use Confidentiality achieved by non-encrypted means may be compromised. Therefore, reducing the amount of encryption without limiting the eavesdropper's eavesdropping range while ensuring network confidentiality has become a research hotspot in secure network coding. The present invention aims at the two actual situations mentioned above, and uses a safe and effective method to realize confidential communication. At the same time, in network coding, once a tampering attack is encountered, the coverage of errors will be expanded. The present invention takes into account the integrity check function of information, and integrates the functions of network confidentiality and integrity check.

Contents of the invention

The present invention provides a method and device for secure network code transmission using a cache node, which can realize secure transmission of network code by encrypting source information, and can use an intermediate node with a cache function to realize integrity verification of data packets The function has the advantages of small amount of encryption, does not limit the eavesdropper's eavesdropping ability, and can provide the function of integrity verification at the same time.

For reaching above-mentioned object of invention, following technical scheme is arranged here:

Secure network coding transmission method using cache nodes: Random linear network coding is the transmission method adopted in the present invention. Random linear network coding means that the coding node performs linear operations on the received data packets, and the coding vector used is randomly selected in the finite field of. Due to the different types of nodes, the operations at the source, intermediate nodes and sink are different.

Finite field: the set F={a, b, ...}, two operations are defined on the elements of F: "+" and "*", and the following three conditions are satisfied:

1. The elements of F constitute a commutative group with respect to the operation "+", and its unit element is set to be 0.

2. The elements of F\{0} form a commutative group with respect to the operation "*". That is, after elements in F exclude element 0, an exchange group is formed with respect to "*".

3. The allocation rate is established, that is, for any element a, b, c∈F, there is always a*(b+c)=(b+c)*a=a*b+a*c

When the number of elements in an F field is finite, it is called a finite field. It is assumed here that the finite field is sufficiently large.

The concrete operating method of the present invention at source, intermediate node and letter sink is as follows:

Source: Construct a data packet, including three parts: encoding vector, payload and integrity check code; the encoding vector is randomly selected in the finite field and placed in front of the data packet; one-dimensional information of the source information is encrypted, Then use the hash function and calculation formula to process other source information to obtain the information for network transmission, and use the randomly selected encoding vector to encode the information for network transmission to obtain the load; according to the check code formula, encoding Vectors and payloads compute integrity checksums.

Intermediate node: After receiving the data packet, the intermediate node first performs an integrity check. If it has not been tampered with, it first performs a network coding operation, and then calculates a new integrity check code; if it is tampered with, it needs to apply to the upstream node for retransmission. After the correct data packet is obtained, the data packet is encoded and reassembled, and a new data packet and a new integrity check code are constructed and transmitted downward. Since the intermediate node has a cache function, when the downstream data packet finds an error, it can request the upstream node to retransmit directly, which increases the complexity of the intermediate node, but reduces the number of links occupied by the possible retransmission process.

Sink: After receiving the data packet, the sink completes the integrity check function. If the data packet is tampered with, it needs to request the upstream node to retransmit it. If it has not been tampered with, it can be directly decoded.

The secure network coding transmission device using cache nodes: the source is the information input device and the data packet construction device, the intermediate node is the data packet "storage-encoding-forwarding" device, and the sink is the data packet receiving and decoding device.

As can be seen from the above technical solutions, the present invention has the following advantages:

In the present invention, only part of the source information needs to be encrypted, which has greater advantages than the existing method of encrypting source information, and the complexity of encryption and decryption is also greatly reduced; the eavesdropper's ability to eavesdrop is not limited, that is, Any link of the network can be eavesdropped, but the eavesdropper has limited computing power and cannot obtain the original information through exhaustive methods; the functions of confidentiality and integrity verification are realized simultaneously without interference.

Description of drawings

In order to illustrate the technical solution of the present invention more clearly, the accompanying drawings that need to be used in the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are flow charts of the present invention. For the information input and output diagrams of the receiver and the sink, those skilled in the art can also obtain other drawings based on these drawings without any creative work.

Fig. 1 is a flowchart of the present invention;

Fig. 2 is the realization device figure of the present invention;

detailed description

Embodiments are embodied here according to the description of the summary of the invention.

Fig. 1 is a flowchart of the present invention, as shown in Fig. 1, the transmission process of data packet is carried out according to the order of information source, intermediate node and information destination, and information source, intermediate node and information destination are different to the operation of data packet , so the present invention is introduced in three parts.

Source: The source has the function of constructing data packets and hiding source information. The specific implementation method is as follows:

S101: The data sent by the source can be expressed as X=(X ₁ X ₂ ...X _j ), and there are j dimensions in total. The dimension here can be understood as a total of j-dimensional data to be sent, and one-dimensional data is sent in sequence; each All the dimensional data correspond to the n-dimensional information vector _{Xi = (x i1 x i2} ... x _in ) ^T , i = 1 ... j, for the convenience of operation, it is necessary to determine the first information of each dimensional data in the n-dimensional data Encrypted, here you can use but not limited to the AES encryption method to encrypt x _i1 into E _i .

S102: After obtaining the encrypted data, construct the data transmitted in the network sent by the source. In order to make all the data related to the encrypted data and ensure that the information cannot be decrypted, the hash function h() is used here, because The hash function is one-way. According to the input x, h(x) can be easily calculated, but according to h(x), it is computationally impossible to obtain x. The process of processing using a hash function is as follows:

$\left\{\begin{array}{c}{x_{i1}}^{\′}={\mathrm{E.}}_i+h\left({x_{i2}}^{\′}\right)\\ {x_{i2}}^{\′}=x_{i2}+h\left(x_{i1}\right)\\ {x_{i3}}^{\′}=x_{i3}+h\left(x_{i1}\right)\\ .\\ .\\ .\\ {x_{\mathrm{in}}}^{\′}=x_{\mathrm{in}}+h\left(x_{i1}\right)\end{array}\right.$ (i=1...j)

And x _i1 ′=E _i +h(x _i2 ′) can not only guarantee the confidentiality, but also make the data transmitted in the network have the same form, here use X _i ′=(x _i1 ′x _i2 ′…x _in ′) ^T , i=1...j means the data transmitted in the network, and i=1...j means there are j sets of data. After calculating the data transmitted in the network, it is assumed that the encoding vector representation method is D _i ¹ =(d _i1 ¹ …d _in ¹ )i=1,…k, D ¹ =(D ₁ ¹ D ₂ ¹ …D _k ¹ ) ^T , for the tth group of transmitted information in the network, the calculated load Y _i ¹ =D _i ¹ X _i ′i=1,...,k, Y _i ¹ =(y _i1 ¹ y _i2 ¹ ...y _ij ¹ ) i=1,...,k, the obtained Y _i ¹ is the payload of the data packet. Multiple payloads can be placed side by side in a packet.

After calculating the load, the source needs to calculate the integrity check code, through the formula ${m_i}^1=\underset{m=1}{\overset{j}{\mathrm{\Σ}}}{\left({\mathrm{the\; y}}_{\mathrm{im}}^1\right)}^{m+1}+\underset{m=1}{\overset{\mathrm{no}}{\mathrm{\Σ}}}{\left(d_{\mathrm{im}}^1\right)}^{m+1}i=\mathrm{1,2}\&Center\; Dot;\·\&Center\; Dot;k,$ can be calculated.

S103: After obtaining the encoding vector, payload and check code, the information source can compose a data packet based on these data for network transmission. The format of the data packet sent by the source is as follows. The 1 in the upper right corner means to distinguish the data packets in different positions in the network, which are marked with different upper corner marks. For example, the s used later has the same meaning:

Intermediate node: After the intermediate node receives the data, it needs to perform an integrity check first. If the information is confirmed to be complete, then construct a new data packet and forward the data packet. The intermediate nodes are divided into two types, namely, encoding nodes and non-encoding nodes. Nodes, coded nodes can perform integrity checks on received data packets, encode them and then forward them, and non-encoded nodes can perform integrity checks on received data packets and forward them directly. The specific implementation process is as follows:

For an intermediate node with cache function, firstly it is necessary to check the integrity of the data packet S104, according to the received data packet, use the formula Calculate the integrity check code and compare it with the received integrity check code. If the same proves that the data packet has not been tampered with, use the current network encoding vector to perform the network encoding operation. Note that only the encoding vector and payload , it is not necessary to perform network coding operations on the integrity check code. The integrity check code is recalculated after the new encoding vector and payload are obtained, and then a new data packet is constructed, including the encoding vector, payload and new complete If it is not the same, it proves that the data packet has been tampered with, and the upstream node is requested to retransmit S105 and check until the complete data packet is received, and then use the current network coding vector for network The encoding operation is also only performed on the encoding vector and payload, and the network encoding operation on the integrity check code is not required. The integrity check code is recalculated after obtaining the new encoding vector and payload, and then constructs new data packet, including encoding vector, payload and new integrity check code, and transmit it downward S106. Since the intermediate node needs to retransmit the data, the intermediate node must have a cache function, that is, cache the currently transmitted data, so that when the downstream node needs to retransmit the upstream node, it can directly call the data in the cache. Therefore, this retransmission mode is only suitable for electrical networks, not for optical networks.

The format of the obtained data packet is still as follows, and the format of the data packet in the network has not changed.

Sink: After receiving the data packet, the sink needs to perform integrity check and decode.

The sink first performs an integrity check. If the data packet is complete, it will perform decryption and decoding operations; if it is incomplete, it needs to request the upstream node to retransmit. After the correct data packet is obtained, the decryption and decoding operation will start.

Integrity check: After receiving the data packet, the sink checks whether the data packet has been tampered with according to the calculation formula of the integrity check code. If the data packet is complete and has not been tampered with S108, then the sink begins to check the received data. Decoding operation; if the received data packet is tampered with, then request the upstream node to retransmit.

Decoding process: S109 After receiving the data packet, the sink can recover the information sent by the source for network transmission according to the transmission mechanism of the network coding. The in-degree of the sink is set to r. In order to make the decoding work normally, it is required that ( r≥n). The specific decoding process and formula are as follows:

Since the intermediate node does not reassemble the data packet, but only performs linear operations, the corresponding functions of each part of the data packet are exactly the same as before, and the format of the data packet obtained by the sink is the same as the format of the data packet received by the intermediate node. , so it can be known that the data obtained by the sink is:

According to the transmission mechanism of network coding and the composition of data packets, the following formula can be obtained:

Since (r≥n), only the r-dimensional function is needed to obtain the information sent by the source for network transmission, X _i ′=(x _i1 ′x _i2 ′…x _in ′) ^T , i=1…j , according to the construction process of Xi ′, E _i = _xi1 ′-h( _xi2 ′) can be obtained, according to the shared key, E _i can be _decrypted to obtain _xi1 , and all information can be calculated according to the following formula.

$\left\{\begin{array}{c}{x}_{i2}={x_{i2}}^{\′}-h\left(x_{i1}\right)\\ x_{i3}={x_{i3}}^{\′}-h\left(x_{i1}\right)\\ .\\ .\\ .\\ x_{\mathrm{in}}={x_{\mathrm{in}}}^{\′}-h\left(x_{i1}\right)\end{array}\right.$ (i=1...j)

So the sink can recover the source information.

The present invention has different functions in the information source, intermediate node and information destination. The information source mainly plays the role of constructing the data packet, the intermediate node plays the role of verification-forwarding-retransmission, and the information destination plays the role of checking the integrity of the data packet. And the function of recovering the information sent by the source.

Fig. 2 is the realization device figure of the present invention:

In the present invention, the information source 201 is an information input device and a data packet construction device, corresponding to steps S101-S103, the information source calculates the integrity check code according to the input information and the check code formula, and then encrypts part of the information source information, Use the hash function and certain calculation formulas to randomize other information of the source, and use the encoding vector to perform network encoding calculation on the randomized data to obtain the load. The data packet is constructed according to the sequence of encoding vector, payload and integrity check code, and then the source outputs the data packet.

The intermediate node 202 is a "storage-encoding-forwarding" device for data packets, corresponding to steps S104-S107, the intermediate node calculates the integrity check code for the data packets from the source or other intermediate nodes, and simultaneously follows the received data packet If they are the same, it proves that the data packet is complete. If not, it proves that the data packet has been tampered with. You can request the upstream node to retransmit until the correct data packet is received. The intermediate node performs network coding operation on the encoding vector and payload part of the received correct data packet, calculates the integrity check code according to the obtained new information, forms a new data packet and forwards it downward.

The sink 203 is a device for receiving and decoding data packets, corresponding to steps S108-S109, the input of information is the data packets received by the sink, after receiving, the sink checks the integrity of the data packets, if the data packets are complete, then directly Decoding and decryption is enough; if the data packet is not complete, then request the upstream node to retransmit until the complete data packet is received, and then decode and decrypt to obtain the information sent by the source.

The above are only common specific implementations of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed in the present invention. , should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (6)

1. A secure network coding transmission method using cache nodes, characterized in that the method comprises the steps: Step 1: Specially specify the format of the data packet, including three components: encoding vector, payload and check code; Step 2: At the source, encrypt one dimension of the source information, and process the remaining information by using a hash function and the following calculation formula: the data sent by the source is expressed as j dimension X=(X ₁ X ₂ ...X _j ), where each dimensional data corresponds to n-dimensional information vector X _i =(x _i1 x _i2 …x _in ) ^T , i=1…j, and x _i1 is encrypted as E _i , then each dimensional data is converted to Among them, h(x) is a hash function, so that other information is related to the encrypted information, and the processed data of each dimension is the information transmitted in the network, and the information transmitted in the network is used to calculate the load and integrity check code , to construct a data packet; Step 3: At the intermediate node, the data packet is firstly checked for integrity, then encoded by the network, and then a new integrity check code and new data packet are constructed and forwarded, that is, the intermediate node works in the "verify - Encoding - Forwarding" mode; Step 4: At the sink, after receiving the data packet, the data packet is first checked for integrity, and after the complete data packet is confirmed, it is decoded to obtain the data sent by the source; Step 5: At the intermediate node and the sink, if the integrity check finds that the data packet is not complete, then the upstream node needs to be requested to retransmit. 2. The method according to claim 1, the forming step of the data packet mainly comprises the following processes: The network transmission adopts the method of random network coding, and the coding vector is randomly selected in the finite field, assuming that the finite field is large enough; the load is calculated by using the coding vector and the information transmitted in the network; the integrity check is calculated by using the check code formula, the load and the coding vector check code. 3. The method according to claim 1, wherein the dimension of the information vector is the same before and after encryption, and only one dimension of each information source information vector needs to be encrypted, and other information does not need to be encrypted, only needs to be encrypted. Dependency processing. 4. The method according to claim 1, since the intermediate node has a data cache function, if the intermediate node and the sink find that the data has been tampered with during the verification process, they will request the directly connected upstream node to retransmit. 5. The method according to claim 1, the sink first uses the information of the received data packet to check the integrity, and only performs the decoding operation if the data packet is complete. 6. A secure network coding transmission device using cache nodes, characterized in that the device includes three components: a source, an intermediate node and a sink: Source: the sending end of the information, which completes the calculation of the integrity check code, the generation of the hash function, the coding of the source and the construction of the data packet; wherein, the source completes the processing of the data according to the following steps: the data sent by the source Expressed as j-dimensional X=(X ₁ X ₂ …X _j ), where each dimensional data corresponds to n-dimensional information vector X _i =(x _i1 x _i2 …x _in ) ^T , i=1…j, and Encrypt x _i1 into E _i , then the data of each dimension is converted into Among them, h(x) is a hash function, and the processed data of each dimension is the information transmitted in the network; Intermediate node: Cache the received information, temporarily store the received data of the upstream node, and transmit it to the downstream node, and send the cached information directly to the downstream node when the downstream node receives an error data request; it has integrity checking test function; Sink: The receiving end of the information completes the function of integrity verification, and decrypts and decodes the data packet.