TWI625957B - Method and system of verifiable data streaming - Google Patents

Abstract

A method of verifiable data streaming, including the following steps. In the client device: obtaining the ith data D(i), where i is an integer greater than or equal to 1; transmitting the encrypted ith data E[D(i)] to the server device; and updating its arithmetic Merkle Tree and store only the data of all root nodes. In the server device: receiving the encrypted ith data E [D(i)] transmitted from the client device; and updating its arithmetic Merkle tree, and storing the data of all the nodes.

Description

Verifiable data stream method and system

The present invention relates to a data streaming method, and more particularly to a verifiable data streaming method and system in which a client device can verify whether the data returned by the server device is correct.

At present, the development of the Internet of Things and big data technology has achieved initial results. Through the Internet of Things and big data technology, users' behaviors can be known, so that enterprises can find a business method that may be profitable. Therefore, the client device acquires a lot of data, and is unlikely to store the data by itself, so the client device sends the data to the server device (for example, a server) of the server for storage. However, when the client device queries the server device for the previous data, there may be a problem that it is impossible to confirm whether the data returned by the server device is correct, that is, the server device cannot be prevented from deceiving the client device.

For example, the client device obtains the data D _i at time t=i and transmits the data D _i to the server device for storage, where i is an integer greater than or equal to 1. However, at time t=i, since the client device does not store the previously obtained data D _j (j is an integer less than i), the client device has no way to know whether the data D _j queried by the server device is correct. . Therefore, there is a need for a verifiable data stream method and system that allows a client device to verify the data returned by the server device without storing too much data to determine the authenticity.

The embodiment of the invention provides a method for verifying data stream, which includes the following steps. In the client device: obtaining the ith data D(i), where i is an integer greater than or equal to 1; transmitting the encrypted ith data E[D(i)] to the server device; and updating its arithmetic Merkle Tree, and only store data of all root nodes, where the i-th data D(i) is filled in the i-th node of the bottom layer of the arithmetic Merkle tree, and the data of the parent node of the two nodes is the path weight of the data of the two nodes. . In the server device: receiving the encrypted i-th data E[D(i)] transmitted from the client device; and updating its arithmetic Merkle tree, and storing the data of all the nodes, wherein the encrypted i-th pen The data E[D(i)] is filled in the i-th node of the bottom layer of the arithmetic Merkle tree, and the data of the parent nodes of the two nodes is the sum of the path weights of the data of the two nodes.

The embodiment of the invention provides a method for verifying data stream, which includes the following steps. In the client device: obtaining the i-th data D(i), where i is an integer greater than or equal to 1; transmitting the encrypted i-th data D(i) to the server device; and updating its arithmetic Merkle tree, and Only the data of all the root nodes is stored, wherein the i-th data D(i) is filled in the i-th node of the bottom layer of the arithmetic Merkle tree, and the data of the parent nodes of the two nodes is the sum of the path weights of the data of the two nodes. In the server device: receiving the i-th data D(i) transmitted from the client device; and updating its arithmetic Merkle tree, and storing the data of all the nodes, wherein the encrypted i-th data D(i) is filled in Entering the i-th node of the bottom layer of the arithmetic Merkle tree, the data of the parent node of the two nodes at the bottom of the arithmetic Merkle tree is the sum of the encrypted path weights of the encrypted data of the two nodes, and the data of the parent nodes of the two nodes that are not the bottom layer are The encryption path weights of the data of the two nodes are summed.

The embodiment of the present invention provides a verifiable data stream system, where the verifiable data stream system includes a client device and a server device, wherein the client device and the server device are connected to each other, and the data stream system can be verified. Perform the aforementioned verifiable data stream method.

Accordingly, the provable data stream method and system provided by the embodiments of the present invention have the following advantages compared with the prior art:

(1) reducing the amount of data that the client device needs to store by storing only the data of the root node in the arithmetic Merkle tree of the client device;

(2) actions such as data attachment, data query and data update that can be performed on the server device, that is, support for basic data attachment, data query and data update instructions;

(3) When updating the data, the data of the corresponding nodes in the arithmetic Merkle tree can be updated according to the difference amount, instead of re-establishing the arithmetic Merkle tree, thus reducing the amount of calculation;

(4) One of the verifiable streaming methods of the embodiment can support the client device without encryption and decryption capability, and is therefore particularly suitable for use in an Internet of Things system.

Embodiments of the present invention provide a method and system for verifying data stream, which are mainly implemented by establishing an arithmetic Merkle tree and using homomorphic encryption, wherein the arithmetic Merkle tree is different from a traditional Merkle tree. The data of the parent node of the two adjacent nodes is the sum of the weights of the data of the two adjacent nodes, or the weights of the data of the two adjacent nodes are added, and the weight may be The weight on the path is encrypted or unencrypted.

In the embodiment of the present invention, when acquiring the i-th data, the user equipment fills the i-th data into the i-th node at the bottom of the arithmetic Merkle tree, and constructs an arithmetic Merkle tree, wherein the data of the root node is Data stored instead of the root node is cleared to reduce the amount of data to be stored. The client device may choose to send the ith data to the server device if it is encrypted or not. The server device fills the i-th data or the i-th encrypted data received by the server into the i-th node at the bottom of the arithmetic Merkle tree, and constructs an arithmetic Merkle tree to store the data in all the arithmetic Merkle trees.

When the client device queries the server device for the ith data obtained by the server device, the server device transmits the data of the i-th node at the bottom of the arithmetic Merkle tree, and also transmits the ith node at the bottom of the arithmetic Merkle tree. The information of all sibling nodes on the path from the node to the root node is given to the client device. In this way, the client device can verify, according to the stored data and the data returned by the server device, whether the information of the i-th node of the bottom layer of the arithmetic Merkle tree transmitted by the server device is correct, that is, the service is determined. Whether the end device is bullied.

Furthermore, the verifiable data stream method and system of the embodiment of the present invention further supports a data update instruction. When the client device instructs the server device to update the ith data previously transmitted by the server device to the additionally encrypted data E[K] or the unencrypted material K, in addition to performing the foregoing querying the ith data transmitted by the client device. In addition, the client device calculates the difference between the returned i-th data and the data K, updates the data of the root node on the i-th node of the lowest layer of the arithmetic Merkle tree according to the difference amount, and then instructs the server device to further The data of the i-th node at the bottom of the arithmetic Merkle tree is updated to the encrypted data E[K] or the unencrypted material K. Then, the server device further updates the entire arithmetic Merkle tree according to the amount of difference. In this way, when updating the data, the client device and the server device do not need to delete the existing arithmetic Merkle tree and construct a new arithmetic Merkle tree, and the client device only needs to calculate the ith of the lowest level of the arithmetic Merkle tree according to the difference amount. The data of the root node on the node is updated, and the server device only needs to update the data of all the nodes on the path from the i-th node to the root node of the lowest level of the arithmetic Merkle tree according to the difference amount.

The above is the concept and principle of the verifiable data stream method and system of the present invention, and the details will be carefully explained in conjunction with the following figures.

First, please refer to FIG. 1. FIG. 1 is a block diagram of a verifiable streaming system according to an embodiment of the present invention. The verifiable streaming system 1 includes a client device 11 and a server device 12, wherein the server device 12 and the client device 11 are connected to each other by wire or wirelessly. The client device 11 may be an Internet of Things device and has sensors to continuously acquire data, but the client device 11 may not be limited to an Internet of Things device. The server device 12 may be a cloud server for receiving and storing the data transmitted by the client device 11. The verifiable streaming system 1 supports basic data attachment, data query, and data update commands.

Next, please refer to FIG. 2, which is a schematic diagram of an arithmetic Merkle tree according to an embodiment of the present invention. It should be noted here that although FIG. 2 is exemplified by a 4-layer tree structure, the present invention does not limit the number of layers of the arithmetic Merkle tree, such as 3 layers, 5 layers or more, which are all protected by the present invention. Within the scope. The bottom layer of the arithmetic Merkle tree has eight nodes L1 to L8. The parent node of the nodes L1 and L2 is the node K1, and the data D(K1) of the node K1 may be the weight of the data D(L1) and D(L2) of the nodes L1 and L2 or the data of the nodes L1 and L2 are encrypted. (E[D(L1)] and E[D(L2)]) are added together, for example, K1 data D(K1)=E[D(L1)]+E[D(L2)] or D( K1)= D(L1)]+D(L2), if the weights on the path of node L1, L2 to node K1 are all 1, and the weight used is the weight on the path, instead of using the encrypted weight on the path . According to the above description, those skilled in the art can understand how the data systems of nodes K2 to K4, R1, R2 and RR are calculated.

Further, according to the above, taking the data D(K1) as an example, it can be known that the general formula of the data D(K1) is D(K1)=w ₁₁ D(L1)+w ₂₂ D(L2) and D(K1). =w ₁₁ E[D(L1)]+w ₂₂ E[D(L2)], wherein the weights w ₁₁ and w ₂₂ are the original weights e ₁₁ , e on the path from the node L1, L2 to the node K1 ₂₂ or the encrypted weights E[e ₁₁ ], E[e ₂₂ ]. The selection of the above formula or the selection of the weight determines that the arithmetic Merkle tree is determined according to the actual use conditions.

3A to 3D are diagrams showing data stored at different time points by the client device and the server device according to the embodiment of the present invention. Figures 3A through 3D can be used to explain two different verifiable streaming methods, wherein the first verifiable streaming method is that the client device encrypts the obtained data and sends it to the server device, and the second The verifiable streaming method is that the user equipment directly sends the obtained data to the server device (that is, the user device does not encrypt the obtained data).

The first verifiable streaming method shall be accompanied by Paillier's homomorphic encryption to have the characteristics of E[a]+E[b]=E[a+b] and c∙E[b]=E[c∙b], Where E[*] is the encryption operator. In addition, the second verifiable streaming method must cooperate with full homomorphic encryption to have E[a]+E[b]=E[a+b] and E[a]∙E[b]=E[ The characteristics of a∙b].

First, in Figure 3A, at time t=1, the client device fills the first data D (L1) into node L1, and encrypts the data E[D(L1)] (the first verifiable The stream method) or the data D (L1) (the second verifiable stream method) is sent to the server device. The server device fills the received data D(L1') into the node L1', wherein the data D(L1') is the encrypted data E[D(L1)] (the first verifiable streaming method) or the data D (L1) (the second verifiable streaming method) and store the data D (L1'). Node L1 is the root node in the arithmetic Merkle tree in Figure 3A, so the client device stores the data D (L1).

Next, in FIG. 3B, when time t=2, the client device fills the second data D (L2) into the node L2, and encrypts the data E[D(L2)] (the first verifiable The stream method) or the data D (L2) (the second verifiable stream method) is sent to the server device. The server device fills the received data D(L2') into the node L2', wherein the data D(L2') is the encrypted data E[D(L2)] (the first verifiable streaming method) or the data D (L2) (the second verifiable streaming method) and store the data D (L2'). Next, the client device calculates the data D(K1)=w ₁₁ D(L1)+w ₂₂ D(L2) of the parent node K1 of the nodes L1, L2 to update the arithmetic Merkle tree, where w ₁₁ and w ₂₂ are nodes. L1, L2 to the original weights e ₁₁ , e ₂₂ on the path of node K1.

At this time, the arithmetic Merkle tree has only one root node as the node K1, so the client device only stores the data D (K1) of the node K1 of the arithmetic Merkle tree, and clears all other data. The server device calculates and stores D(K1') of node K1' of the arithmetic Merkle tree, where D(K1')=w' ₁₁ D(L1')+w' ₂₂ D(L2'), where w' ₁₁ And w' ₂₂ is the original weight e' ₁₁ , e ' ₂₂ (the first verifiable streaming method) or the encrypted weight E [e' ₁₁ ] on the path of the node L1', L2' to the node K1' , E[e' ₂₂ ] (the second verifiable streaming method). In other words, the data D(K1') may be E[e' ₁₁ D(L1) + e' ₂₂ D(L2)] (whether the first or second verifiable streaming method, the result is the same).

Next, in FIG. 3C, when the time t=3, the user equipment fills the third data D (L3) into the node L3, and encrypts the data E[D(L3)] (the first verifiable The streaming method) or the data D (L3) (the second verifiable streaming method) is sent to the server device. The server device fills the received data D (L3') into the node L3', wherein the data D (L3') is the encrypted data E[D(L3)] (the first verifiable streaming method) or the data D (L3) (the second verifiable streaming method) and store the data D (L3'). At this time, the arithmetic Merkle tree has two root nodes as nodes K1 and L3, so the client device stores the data D (L3) of the node L3 of the arithmetic Merkle tree, but does not clear the data D (K1) of the node K1, that is, The root node data D(K1) and D(L3) are stored by the client device.

Next, in the 3D picture, when the time t=4, the user equipment fills the fourth data D (L4) into the node L4, and the encrypted data E[D(L4)] (the first verifiable The streaming method) or the data D (L4) (the second verifiable streaming method) is sent to the server device. The server device fills the received data D (L4') into the node L4', wherein the data D (L4') is the encrypted data E[D(L4)] (the first verifiable streaming method) or the data D (L4) (the second verifiable streaming method) and store the data D (L4'). Next, the client device calculates the data D(K2)=w ₃₃ D(L3)+w ₄₄ D(L4) of the parent node K2 of the nodes L3, L4 to update the arithmetic Merkle tree, where w ₃₃ and w ₄₄ are nodes. The original weights e ₃₃ , e ₄₄ on the path from L3, L4 to node K2. Next, the data D(R1)=w ₁₂ D(K1)+w ₃₄ D(K4) of the parent nodes of the nodes K1 and K2 are calculated to update the arithmetic Merkle tree, where w ₁₂ and w ₃₄ are nodes K1 and K2 to the node. The original weights e ₁₂ , e ₃₄ on the path of R1.

At this time, the arithmetic Merkle tree has only one root node as the node R1, so the client device only stores the data D (R1) of the node R1 of the arithmetic Merkle tree, and clears all other data. The server device calculates and stores D(K2') of the node K2' of the arithmetic Merkle tree and the data D(R1') of the node R1', where D(K2')=w' ₃₃ D(L3')+w' ₄₄ D(L4'), D(R1')= w' ₁₂ D(K1')+w' ₃₄ D(K2'), where w' ₃₃ and w' ₄₄ are nodes L3', L4' to node K2' The original weights e' ₃₃ , e ' ₄₄ (the first verifiable streaming method) or the encrypted weights E[e' ₃₃ ], E[e' ₄₄ ] (the second verifiable stream) Method), and w' ₁₂ and w' ₃₄ are the original weights e' ₁₂ , e ' ₃₄ (the first verifiable streaming method) or encrypted after the path of the node K1 ', K2 ' to the node R1 ' Weights E[e' ₁₂ ], E[e' ₃₄ ] (second verifiable streaming method). In other words, the data D(K2') and D(R1') may be E[e' ₃₃ D(L3)+e' ₄₄ D(L4)] and E[e' ₁₂ (e' ₁₁ D(L1)+e ' ₂₂ D(L2)) + e' ₃₄ (e' ₃₃ D(L3)+e' ₄₄ D(L4))] (Whether it is the first or second verifiable streaming method, the result is the same). Note here that, without loss of generality, the above-mentioned weights e _xy and e' _xy are identical to each other, where x and y are integers.

Please continue to refer to the 3D figure. When the client device wants to query the second data obtained by the client device, the server device returns the data D (L2') of the node L2' and the path from the node L2' to the root node R1'. The data D (L1') and D (K2') of all the sibling nodes L1', K2'. Through the data D (L2'), the client device can know what the second data it has obtained. For example, the data D(L2') in the first verifiable data stream method is the data E(D(L2')] encrypted by the data D (L2), so as long as the data D (L2') is decrypted, The data D (L2) can be known. The data D (L2') in the second verifiable data stream method is the data D (L2), so the data D (L2) can be directly known from the data D (L2'). Then, the data stored by the client device is D (R1), so that the authenticity of the data D (L2') can be verified by the data D (R1), D (L1') and D (K2').

Please note that the purpose of the second verifiable data stream method is to make the client device without encryption and decryption capability applicable. In the above example, the data D (K2') returned by the server device can be Changed to return D (K2') decrypted data D (K2), and the client device verifies the trueness of the data D (L2') through the data D (R1), D (L1') and D (K2). Pseudo.

Please continue to refer to the 3D figure. When the client device wants to update the second data transmitted by the client device to the encrypted data E[K] or the data K, the server device returns the data D (L2' of the node L2'. And the data D (L1') and D (K2') of all the sibling nodes L1', K2' on the path from the node L2' to the root node R1' (or the data D (K2') after decryption of the data D ( K2)). At this time, the data stored by the client device is D(R1), so the data D can be verified through the data D(R1), D(L1') and D(K2') (or the data D(K2)) ( The authenticity of L2'). Next, the client device transmits the encrypted data E[K] or the data K to the server device to update the data of the node L2' of the server device to E[K] or K. Then, the client computing device and the original data information K D (L2) of the amount of difference KD (L2), and R1 is the root node information is updated at the node L2 is D (R1) = D (R1 ) + w 22 w 12 (KD(L2)). Next, the client device transmits the difference amount KD (L2) to the server device, the server device calculates the encrypted difference amount E[KD(L2)], and updates the data of the nodes K1' and R1' on the node L2' to D(K1')= D(K1')+ w' ₂₂ E[KD(L2)] and D(R1')= D(R1') +w' ₂₂ w' ₁₂ E[KD(L2)].

Please continue to refer to FIG. 3D. In the second verifiable data stream method, the server device does not know the weight e _{xy of the} client device. Therefore, the client device does not consider the communication cost. The ownership weight e _xy may be transmitted to the server device to cause the server device to generate the encrypted weight E[e _xy ]. However, in consideration of the communication cost, the client device transmits m encrypted random numbers E[x ₁ ] to E[x _m ], where x ₁ to x _m are random numbers generated according to the weight e _xy , and m represents the number of layers of the arithmetic Merkle tree. Then, the server device can calculate m bits b ₁ to b _m corresponding to the weight e _xy , and according to m bits b ₁ ～ b _m and m encryption chaotic numbers E[x ₁ ]～E[x _m ] Calculate the encrypted weight E[e _xy ]=E[b ₁ ]E[x ₁ ]+E[b ₂ ]E[x ₂ ]+...+E[b _m ]E[x _m ]. In this way, the server device can generate the encrypted weights by itself without obtaining the ownership weight e _xy from the client device to reduce the communication cost.

Then, according to the above embodiment, the flow of the client device performing the verifiable streaming method to transmit the data and the stored data is organized as follows. Referring to FIG. 4, FIG. 4 is a flowchart of a method for a client device to perform a verifiable streaming method for transmitting data and storing data according to an embodiment of the present invention. First, in step S41, the client device acquires the i-th data D(i). Then, in step S42, the client device transmits the encrypted ith data E[D(i)] or the unencrypted ith data D(i) to the server device. Thereafter, in step S43, the arithmetic Merkle tree of the client device is updated, and only the data of all the root nodes is stored, wherein the i-th data D(i) is filled in the i-th node of the bottom layer of the arithmetic Merkle tree, and the two nodes are The data of the parent node is the sum of the unencrypted path weights of the data of the two nodes, wherein the unencrypted path weight is the path weight of the node to its parent node. Thereafter, in step S44, the variable i is incremented by 1, that is, i=i+1.

Then, according to the above embodiment, the flow of the server device performing the verifiable streaming method to store the data is organized as follows. FIG. 5 is a flowchart of a server device performing a verifiable streaming method to store data according to an embodiment of the present invention. In step S51, the server device receives the i-th data R(i) from the client device, wherein the i-th data R(i) from the client device is the i-th data D obtained by the user device [ i] Encrypted E[D(i)] or unencrypted D[i]. Then, in step S52, the arithmetic Merkle tree is updated, and the data of all nodes is stored, wherein the data R(i) is filled in the i-th node of the bottom layer of the arithmetic Merkle tree, and the data of the parent nodes of the two nodes is composed of the two nodes. The data is calculated. Thereafter, in step S53, the variable i is incremented by 1, that is, i=i+1.

Please note that in step S52, the data of the parent nodes of the two adjacent nodes at the bottom of the arithmetic Merkle tree is the sum of the unencrypted path weights of the data of the two adjacent nodes at the bottom of the arithmetic Merkle tree, or an arithmetic Merkle tree. The data of the two adjacent nodes of the bottom layer is added by the encrypted secret path weight, wherein the encrypted path weight is the encrypted weight of the path weight of the node to its parent node. In addition, the data of other parent nodes (parent nodes of two adjacent nodes that are not under the arithmetic Merkle tree) is the unencrypted path weight plus or the encrypted path weights of the data of the two child nodes.

According to the above embodiment, the flow of the client device and the server device performing the verifiable streaming method for data query is organized as follows. FIG. 6 is a flowchart of a method for performing a verifiable streaming method by a client device and a server device according to an embodiment of the present invention to perform data query. In step S61, the client device transmits the client device to transmit the data query command Q(i) to query the ith data obtained by the client device. In step S62, the server device returns the data of the i-th node of the bottom layer of the arithmetic Merkle tree and the data of all the sibling nodes on the path of the i-th node of the arithmetic Merkle tree to the root node according to the arithmetic Merkle tree. (or the decrypted data) to the client device. Then, in step S63, the client device knows the ith data obtained by the client device according to the data R(i) returned by the server device, and according to the stored root node data and the data of the aforementioned sibling node (or the decrypted data) Data) Verification of the authenticity of the data R(i).

According to the above embodiment, the flow of the client device and the server device performing the verifiable streaming method for data update is organized as follows. FIG. 7 is a flowchart of a method for performing a verifiable streaming method by a client device and a server device to perform data update according to an embodiment of the present invention. In step S71, the client device transmits a data update command A(i, K) that updates the transmitted ith data to the encrypted material E[K] (or unencrypted material K). In step S72, the server device returns the data of the i-th node of the bottom layer of the arithmetic Merkle tree and the data of all the sibling nodes on the path of the i-th node of the arithmetic Merkle tree to the root node according to the arithmetic Merkle tree. (or the decrypted data) to the client device. Then, in step S73, the client device knows the ith data obtained by the client device according to the data R(i) returned by the server device, and according to the stored root node data and the data of the aforementioned sibling node (or the decrypted Data) Verification of the authenticity of the data R(i).

Next, in step S74, the server device updates the data R(i) of the i-th node at the bottom of the arithmetic Merkle tree to the encrypted material E[K] (or material K). Next, in step S75, the client device calculates the difference between the data K and the data R(i) after decryption (or the data R(i)), and updates the root node on the i-th node of the bottom layer of the arithmetic Merkle tree accordingly. Data, in which the data of the root node on the i-th node of the bottom layer of the Merkle tree is updated to its original data plus the product of each path weight and the difference amount. Then, in step S76, the server device updates the data of all the nodes on the path of the i-th node of the arithmetic Merkle tree to the root node according to the encrypted difference amount, wherein the i-th node of the bottom layer of the arithmetic Merkle tree goes to the root The data of all nodes on the path of the node is updated to the original data plus the product of each path weight (or encrypted path weight) and the difference amount.

According to the above, the method and system for verifying streaming data provided by the embodiments of the present invention can reduce the amount of data that the user equipment needs to store, and can support basic data attachment, data query, and data update instructions. In addition, when the data is updated, the data of the corresponding node in the arithmetic Merkle tree can be updated according to the amount of difference, instead of re-establishing the arithmetic Merkle tree, the number of operations is reduced. On the other hand, one of the verifiable streaming methods can support the client device without encryption and decryption capability, so it is especially suitable for the Internet of Things system.

The content of the above embodiments is at least one of the numerous embodiments of the present invention, and those skilled in the art having the above-mentioned contents can understand the core concept of the invention and understand the above-mentioned contents. The embodiment is modified. In other words, the above-described embodiments are not intended to limit the invention, and the scope of the invention is defined by the text of the following claims.

1‧‧‧ Verifiable data streaming system
11‧‧‧Customer device
12‧‧‧ server device
L1 to L8, K1 to K4, R1, R2, RR, L1' to L4', K1', K2', R1'‧‧‧ nodes
S41～S76‧‧‧Steps
w ₁₁ , w ₁₂ , w ₂₂ , w ₃₃ , w ₃₄ , w ₄₄ ‧ ‧ weights

Figure 1 is a block diagram of a verifiable streaming system in accordance with an embodiment of the present invention.

Figure 2 is a schematic diagram of an arithmetic Merkle tree in accordance with an embodiment of the present invention.

3A to 3D are diagrams showing data stored at different time points by the client device and the server device according to the embodiment of the present invention.

FIG. 4 is a flowchart of a method for a client device to perform a verifiable streaming method for transmitting data and storing data according to an embodiment of the present invention.

FIG. 5 is a flowchart of a server device performing a verifiable streaming method to store data according to an embodiment of the present invention.

FIG. 6 is a flowchart of a method for performing a verifiable streaming method by a client device and a server device according to an embodiment of the present invention to perform data query.

FIG. 7 is a flowchart of a method for performing a verifiable streaming method by a client device and a server device to perform data update according to an embodiment of the present invention.

Claims (10)

A method for verifying data stream, comprising: a user equipment: obtaining an ith data D(i), wherein i is an integer greater than or equal to 1; transmitting the encrypted ith data E[D(i) a] to a server device; and update its arithmetic Merkle tree, and store only the data of all the root nodes, wherein the i-th data D(i) is filled in the i-th node of the bottom layer of the arithmetic Merkle tree, and two nodes The data of the parent node is the sum of the path weights of the data of the two nodes; and the server device: receiving the encrypted ith data E[D(i)] transmitted from the client device; Update its arithmetic Merkle tree and store the data of all nodes, wherein the encrypted i-th data E[D(i)] is filled in the i-th node of the bottom layer of the arithmetic Merkle tree, and the data of the parent nodes of the two nodes The path weights for the data of the two nodes are summed. A verifiable data stream method as described in claim 1 wherein Paillier's homomorphic encryption is employed. The provable data stream method of claim 1, further comprising: the client device transmitting a data query command to the server device to query the ith data D(i) obtained by the client device; The server device returns the data E[D(i)] of the i-th node of the bottom layer of the arithmetic Merkle tree and the data of the i-th node of the bottom layer of the arithmetic Merkle tree to the sibling node of one node; and the client device Decoding the returned data E[D(i)] to know the ith data D(i) obtained by the user, and the data of the client device according to the stored data and the arithmetic Merkle tree bottom layer of the server device The data from the i-th node to the sibling node of the root node verifies the authenticity of the returned data E[D(i)]. The method for verifying the data stream as described in claim 1, further comprising: the client device transmitting a data update command to the server device to update the encrypted ith data E [D] (i)] is E[K], where the data K is encrypted and encrypted as the data E[K]; the server device returns the data E[D(i) of the i-th node of the bottom layer of the arithmetic Merkle tree. And the data of the i-th node of the bottom layer of the arithmetic Merkle tree to the sibling node of a node; the client device decrypts the returned data E[D(i)] to know the i-th pen obtained Data D(i), and the client device verifies the backed up data E[D() according to the data stored by it and the i-th node of the bottom layer of the arithmetic Merkle tree of the server device to the brother node of a node. i)] authenticity; the server device updates the data E[D(i)] of the i-th node of the bottom layer of the arithmetic Merkle tree to the encrypted data E[K]; the client device calculates the data K Update the amount of difference from the data D(i) and update the data of the root node on the i-th node of the bottom layer of the arithmetic Merkle tree to its original data. And adding the product of the difference amount to each corresponding path weight; and the client device transmits the difference amount to the server device, and the server device will perform the node on the i-th node of the bottom layer of the arithmetic Merkle tree The data is updated, wherein the data of the node on the i-th node of the bottom layer of the arithmetic Merkle tree is updated with the original data plus the product of the encrypted difference and the weight of each corresponding path. A verifiable data stream method, comprising: at a client device: obtaining an ith data D(i), wherein i is an integer greater than or equal to 1; transmitting the encrypted ith data D(i) to a server device; and updating its arithmetic Merkle tree, and storing only the data of all the root nodes, wherein the i-th data D(i) is filled in the i-th node of the bottom layer of the arithmetic Merkle tree, and the parent node of the two nodes The data is a total of the path weights of the data of the two nodes; and the server device: receives the i-th data D(i) transmitted from the user device; and updates its arithmetic Merkle tree, and stores all The data of the node, wherein the encrypted i-th data D(i) is filled in the i-th node of the bottom layer of the arithmetic Merkle tree, and the data of the parent node of the two nodes at the bottom of the arithmetic Merkle tree is the encrypted of the two nodes. The encrypted path weights of the data are summed, and the data of the parent nodes of the non-bottom nodes is the sum of the encrypted path weights of the data of the two nodes. The verifiable data stream method as described in claim 5, wherein the isomorphic encryption is used. The method for verifying the data stream as described in claim 5, further comprising: the client device transmitting a data query command to the server device to query the ith data D(i) obtained by the client device; The server device returns the data [D(i)] of the i-th node of the bottom layer of the arithmetic Merkle tree and the decrypted data of the i-th node of the bottom layer of the arithmetic Merkle tree to the sibling node of one node; and the user The end device knows the acquired data ith data D(i) according to the returned data D(i), and the data of the client device according to the stored data and the bottom layer of the arithmetic Merkle tree of the server device The decrypted data from the i nodes to the sibling nodes of the root node verifies the authenticity of the returned data D(i). The method for verifying the data stream as described in claim 5, further comprising: the client device transmitting a data update command to the server device to update the encrypted ith data D (i) Is the data K; the server device returns the data D(i) of the i-th node of the bottom layer of the arithmetic Merkle tree and the decrypted data of the i-th node of the bottom layer of the arithmetic Merkle tree to the sibling node of one node; The client device verifies the authenticity of the returned data D(i) according to the stored data and the decrypted data of the i-th node of the bottom layer of the arithmetic Merkle tree of the server device to the node of the node; the server The device updates the data D(i) of the i-th node of the bottom layer of the arithmetic Merkle tree to the material K; the client device calculates the difference between the data K and the data D(i), and computes the bottom of the arithmetic Merkle tree The data of the root node on the i-th node is updated with its original data plus the product of the difference amount and each corresponding path weight; and the client device transmits the difference amount to the server device, and the server device Arithmetic Merkle tree The data of the node on the i-th node of the layer is updated, wherein the data of the node on the i-th node of the bottom layer of the arithmetic Merkle tree is updated with the original data plus the product of the encrypted difference and the weight of each corresponding encryption path. . The method for verifying the data stream as described in claim 5, further comprising: the client device transmitting m encrypted random numbers E[x ₁ ] to E[x _m ] to the server device, wherein x ₁ to x _m are random numbers generated according to weights of each path, m represents the number of layers of the arithmetic Merkle tree of the client device and the server device; and the server device calculates m bits according to the corresponding path weights b ₁ to b _m , and calculating the encryption of the arithmetic Merkle tree with the server device based on the m bits b ₁ to b _m and the m encrypted random numbers E[x ₁ ] to E[x _m ] Each path weight E[e _xy ]=E[b ₁ ]E[x ₁ ]+E[b ₂ ]E[x ₂ ]+...+E[b _m ]E[x _m ]. A verifiable data stream system for performing a verifiable data stream method according to any one of claims 1-9, comprising: the client device; and the server device, connecting the client device.