JP2011139240A - Distribution route determination device of content distribution system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a distribution route determination device of a content distribution system capable of determining a distribution route high in reliability against bugging and interference, in a system for distributing a plurality of partial contents subjected to threshold secret sharing and a plurality of redundant identical contents via different routes. <P>SOLUTION: A maximum independent route number obtaining part 102 calculates a maximum number m of link-independent (first implementation form) or node-independent (second implementation form) routes from respective distribution source nodes to a distribution destination node. A distribution route determination part 103 includes a first distribution route determination part 103a for determining k independent routes from among the m independent routes when the number k of partial contents to be distributed to the distribution destination node is not larger than the maximum number m, and a second distribution route determination part 103b for determining k routes including the m independent routes when the number k of partial contents to be distributed to the distribution destination node is larger than the maximum number m. A route notification part 104 notifies the respective distribution source nodes 1 of determination results of the k routes. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a distribution route determination apparatus of a content distribution system, and in particular, divides one content into a plurality of partial contents and distributes them on a network, and these partial contents are routed to one distribution destination node. It is related with the delivery route determination apparatus of the content delivery system suitable for the threshold secret sharing delivered by.

  Divide one content into n pieces of encrypted partial content, and distribute secrets so that the original content cannot be restored unless more than k (<= n) pieces of partial content are gathered Non-Patent Document 1 discloses threshold secret sharing.

  Also, Patent Documents 1 and 2 disclose techniques for secretly distributing and holding n partial contents divided by a plurality of nodes in order to distribute the risk of data retention.

Shamir, Adi (1979), "How to share a secret", Communications of the ACM 22 (11): 612-613

JP 2009-122731 A JP 2009-10531 A

  Original data can be restored by collecting arbitrary k partial contents from n partial contents, but original data cannot be restored from (k-1) partial contents (k, n) With threshold secret sharing, at least k The partial contents are distributed and distributed to the distribution source nodes on the network, and the partial contents are distributed from the distribution source node that holds the partial contents to the distribution destination node that is to restore the original data.

  At this time, if the distribution route of each partial content passes through the same link or the same node, the original data is restored just by eavesdropping less than k links or less than k nodes, so the safety factor is lowered. Resulting in. Therefore, in data distribution to which (k, n) threshold secret sharing is applied, it is desirable that the k routes as much as possible do not pass through the same link or the same node.

  In addition, even in cases other than threshold secret sharing, in the case of redundancy in which the same content is distributed by a plurality of routes, not only all routes pass through the same link or the same node, but also some routes have the same link or the same node. Even when passing through the network, the degree of safety against link failure and node failure is reduced.

  The object of the present invention is to solve the above-mentioned problems of the prior art, and in a system that distributes a plurality of partial contents with threshold secret sharing and a plurality of redundant same contents through different routes, the reliability of wiretapping and failure An object of the present invention is to provide a distribution route determination device for a content distribution system that can determine a high distribution route.

  In order to achieve the above object, the present invention is characterized in that the following measures are taken.

  (1) A content distribution system that divides content to be distributed into a plurality of partial contents, distributes them to distribution source nodes on the network, and distributes each partial content from each distribution source node to the distribution destination node through a plurality of routes. In the delivery route determination device, based on the topology of the network, means for calculating the maximum number m of link-independent routes from each delivery source node to the delivery destination node, and the number k of partial contents delivered to the delivery destination node When the maximum number is m or less, the first determination means for determining k paths from the m link-independent paths, and the number k of partial contents to be distributed to the distribution destination node is greater than the maximum number m. A plurality of second determination means for determining k paths including the m link-independent paths, and each determination means has a total probability based on a probability that the link of each path is wiretapped. Wherein the probability that the path is eavesdropping determines the combinations of k this path is minimized.

  (2) A content distribution system that divides content to be distributed into multiple partial contents, distributes and distributes them to distribution source nodes on the network, and distributes each partial content from each distribution source node to the distribution destination node through multiple routes. In the delivery route determination device, the means for calculating the maximum number m of node-independent routes from each delivery source node to the delivery destination node based on the network topology, and the number k of partial contents delivered to the delivery destination node If the maximum number m or less, the first determination means for determining k paths from the m node-independent paths, and the number k of partial contents to be distributed to the distribution destination node is greater than the maximum number m. A second determining means for determining k paths including the m node-independent paths, each determining means based on a probability that a node on each path is wiretapped, The probability that the path of Te is eavesdropping, characterized in that to determine the combination of k this path is minimized.

  (3) The content to be distributed is divided into n based on the (k, n) threshold secret sharing method, and k of the n partial contents are distributed from each distribution source node without duplication. And

  (4) In a distribution route determination apparatus of a content distribution system in which a plurality of identical contents are distributed and distributed to distribution source nodes on a network and each content is distributed from each distribution source node to a distribution destination node by a plurality of routes, the network topology And calculating the maximum number m of link-independent paths from each distribution source node to the distribution destination node, and if the number k of contents distributed to the distribution destination node is equal to or less than the maximum number m, A first determination unit that determines k paths from among the link-independent paths, and if the number k of contents to be distributed to the distribution destination node is greater than the maximum number m, the m link-independent paths Second determining means for determining k paths including the path, and each determining means has a minimum probability that a failure will occur in all routes based on a probability that a failure will occur in the link of each route. And And determining the combination of k this route.

  (5) In a distribution route determination apparatus of a content distribution system in which a plurality of identical contents are distributed and distributed to distribution source nodes on a network and each content is distributed from each distribution source node to a distribution destination node by a plurality of routes, the network topology And calculating the maximum number m of node-independent paths from each distribution source node to the distribution destination node, and if the number k of contents distributed to the distribution destination node is equal to or less than the maximum number m, A first determination unit that determines k paths from among the node-independent paths, and if the number k of contents to be distributed to the distribution destination node is greater than the maximum number m, the m nodes are independent. Second determining means for determining k paths including the path, and each determining means has a probability that a failure will occur in all routes based on a probability that a node on each route will fail. Minimum and And determining the combination of k the path that.

  According to the present invention, the following effects are achieved.

  (1) Maximize the number of links that can restore the original content if wiretapped, and determine the distribution route of partial content that minimizes the probability that all such links will actually be wiretapped it can. Therefore, even when partial content that is secretly distributed and held by a plurality of nodes is distributed via a route including a link that may be intercepted, secure content distribution can be performed.

  (2) Partial content distribution route that maximizes the number of relay nodes that can restore the original content if wiretapped, and minimizes the probability that all such relay nodes are actually wiretapped Can be determined. Therefore, even when partial content that is secretly distributed and held by a plurality of distribution source nodes is distributed via a node that may be wiretapped, safe content distribution is possible.

  (3) When content is distributed based on the (k, n) threshold secret sharing method, the distribution route of the partial content divided into n can be appropriately determined.

  (4) In redundancy to simultaneously distribute the same content via multiple routes, the number of links that would make content distribution impossible when link failures occur simultaneously is maximized, and all such combinations of links actually fail. Since a content distribution route that minimizes the probability of occurrence can be determined, highly reliable redundancy is possible.

  (5) In redundancy that distributes the same content simultaneously through multiple routes, the number of nodes that can no longer be delivered when a node failure occurs at the same time is maximized. Since a content distribution route that minimizes the probability of occurrence can be determined, highly reliable redundancy is possible.

It is the figure which showed the network structure of the content delivery system with which this invention is applied. It is a functional block diagram of a delivery route determination device. It is the flowchart which showed the operation | movement of 1st Embodiment of this invention. It is the figure which showed a mode that the link independent path | route was established by 1st Embodiment of this invention. It is the flowchart which showed the operation | movement of 2nd Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing a network configuration of a content distribution system to which the present invention is applied. Here, content distribution using (k, n) threshold secret sharing will be described as an example.

  U distribution source nodes 1 are arranged in the network 3 to be controlled, and n partial contents cp (cp1 to cpn) obtained by dividing one content c into n are distributed to each distribution source node 1. Has been placed. The partial content cp distributed and distributed in each distribution source node 1 is not limited to one, and a plurality of different partial contents cp may be allocated, and the same partial content cp is overlapped in a plurality of distribution source nodes 1 Sometimes it is done.

  The distribution destination node 2 has a content reproduction function for reproducing the original content c from at least k partial contents cp. The distribution route determination server 4 determines a route for distributing k pieces of partial content from each distribution source node 1 to the distribution destination node 2 without omission and notifying each distribution source node 1.

  FIG. 2 is a functional block diagram showing the configuration of the main part of the delivery route determination server 4. The topology acquisition unit 101 acquires the topology of the network 3. The maximum independent route number solving unit 102 determines the maximum number m of link-independent (first embodiment) or node-independent (second embodiment) routes from each distribution source node 1 to the distribution destination node 2. This is calculated by solving the integer programming method (first embodiment) or the fourth integer programming method (second embodiment).

  When the number k of partial contents to be delivered to the delivery destination node is equal to or less than the maximum number m, the delivery route determination unit 103 uses a second integer programming method (first embodiment) or a fifth integer programming method (first 2 embodiment), the first distribution route determination unit 103a that determines k independent routes from the m independent routes, and the maximum number m of partial contents to be distributed to the distribution destination node is m. If there are more, k paths including the m independent paths are determined by solving the third integer programming (first embodiment) or the sixth integer programming (second embodiment) described later. A second delivery route determination unit 103b. The route notification unit 104 notifies each distribution source node 1 of the determination result of the k routes.

  In the first embodiment of the present invention, for distributing arbitrary k pieces of n partial contents cp secretly held by U pieces of delivery source nodes 1 to the delivery destination node 2 via the network 3 In route selection, assuming that there is a possibility that partial content cp in the middle of distribution may be wiretapped by a link on the route, a route that minimizes the probability that all k partial content cps are wiretapped is determined. .

Next, the operation of the embodiment of the present invention will be described with reference to the flowchart of FIG. In step S <b> 1, the topology (N, Link) of the network 3 is acquired by the topology acquisition unit 101. In step S2, the maximum number m of link-independent paths that do not include a common link among a large number of paths from U distribution source nodes 1 to distribution destination nodes 2 holding partial content cp is calculated as follows. It is obtained by solving the first integer programming in the maximum independent path number solving unit 102. In the first integer programming, constants are defined as follows:

N: Set of nodes that make up the network
n: Node
NC: A set of nodes holding partial contents
c: Node holding partial content
d: Distribution destination node
L: Collection of links that make up the network
l: Link

The variables are defined as follows:

xl: A binary variable that is “1” if a link-independent route passes through link l and “0” if it does not pass.
M: Number of link independent routes

  In the first integer programming, the constraint equations are given by the following equations (1) to (5). Expression (1) is a constraint that the number of routes entering the distribution source node 1 that holds the partial content cp is zero, and is a condition that the route is not looped. Equation (2) is a constraint that the total number of routes from each distribution source node 1 is equal to the number M of link-independent routes. Equation (3) is a constraint that the number of routes entering the distribution destination node 2 is M. Equation (4) is a constraint that the number of routes from the distribution destination node 2 is zero. The expression (5) is a constraint that the number of incoming routes is the same as the outgoing route number in relay nodes other than the distribution source node 1 and the distribution destination node 2.

  In this embodiment, all routes must be link-independent, and a plurality of routes do not pass through each link, so the following equation (6) is given as a link-independent condition.

  Since the objective function to be maximized is the variable M, in this step S2, the maximum number m of the number M of link-independent paths is obtained by solving the first integer programming.

  In step S3, the maximum number m of link independent paths is compared with the threshold value k. If the maximum number m is greater than or equal to k, the process proceeds to step S4 in order to select k paths from m link independent paths and distribute k partial contents. As a result, the attacker cannot restore the original content c without eavesdropping on at least k links.

In step S4, k independent routes for distributing each partial content cp are the first distribution so that the probability that the original content c is leaked by eavesdropping on the k links is minimized. It is determined by the route determination unit 103a. Here, k paths are determined by solving the second integer programming method described in detail below. In the second integer programming method, constants are defined as follows:

N: Set of nodes constituting the network
n: Node
NC: A set of nodes holding partial contents
c: Node holding partial content
d: Distribution destination node
L: Collection of links that make up the network
l: Link
LK: A set of k links that are eavesdropped
LKj: Set of links included in the jth combination in LK
P j: Probability of eavesdropping on all links included in LKj
nin: A set of links that end at node n
nout: A set of links starting from node n

The variables are defined as follows:

Xl (i): A binary variable that is “1” if the i (1 to k) th path passes through link l, and “0” if it does not pass.
Yj (i): a binary variable that is “1” if the i (1 to k) th route passes through the link included in LKj, and “0” otherwise.
Zj: A binary variable that is “1” if all routes pass through links included in LKj, and “0” otherwise.
Obj: Probability of leaking the original content c due to eavesdropping on k links

  In the second integer programming, the constraint equations are given by the following equations (7) to (9). Equation (7) is a path conservation rule in which each k route passes only one of the links exiting the distribution source node 1, that is, k routes exit from one of the distribution source nodes 1. is there. Expression (8) is a path preservation rule that k paths always pass through the link entering the distribution destination node 2. The expression (9) is a path preservation rule that, in the relay nodes other than the distribution source node 1 and the distribution destination node 2, the k routes do not go out unless they enter, and always go out when they enter.

  In this embodiment, all routes must be link-independent, and a plurality of routes do not pass through each link l. Therefore, the following equation (10) is a link-independent condition.

  Furthermore, in the present embodiment, the following equation (11) is given as a condition for the route to pass through the link set that is eavesdropped. Further, the following equation (12) is given as a condition that all routes pass through the link set to be wiretapped.

  In the present embodiment, the original content c leaks when all routes pass through at least one of the k links that are eavesdropped. Since the object of the present embodiment is to minimize such a probability, the objective function to be minimized is given by the following equation (13). In this embodiment, the probability that each link l is wiretapped is known, and the probability Pj is calculated as, for example, the product of wiretapping probabilities based on the wiretap probability of all links l included in LK j.

  In this step S4, k independent routes to which each partial content cp is to be distributed are determined from the value of Xl (i) obtained by solving the second integer programming.

  On the other hand, if it is determined in step S3 that the maximum number m of link-independent paths is smaller than the required number of paths k, the process proceeds to step S5. In this case, the attacker may be able to restore the original content c by simply eavesdropping m links, which is fewer than k. However, if the k routes for distributing the partial content include m link-independent routes, the attacker cannot restore the original content c only by eavesdropping on m-1 links.

  Therefore, in step S5, as shown in FIG. 4, for example, m (<k) link-independent paths are included, and the probability that the original content c is leaked due to wiretapping of m links is minimized. The k distribution paths for distributing the partial content cp are determined by the second distribution path determination unit 103b.

In the present embodiment, such k paths are determined by solving a third integer programming method described in detail below. The constants in the third integer programming are defined as follows:

N: Set of nodes constituting the network
n: Node
NC: A set of nodes holding partial contents
c: Node holding partial content
d: Distribution destination node
L: Collection of links that make up the network
l: Link
LK: A set of m link links
LKj: Set of links included in the jth combination in LK
Pj: Probability that all links included in LKj will be wiretapped
nin: A set of links that end at node n
nout: A set of links starting from node n

In the third integer programming method, variables are defined as follows.

Xl (i): A binary variable that is “1” if the i (1 to k) -th path passes through the link l and “0” if it does not pass.
Yj (i): A binary variable that is “1” if the i (1 to k) -th path passes through the link l included in LKj, and “0” otherwise.
Zj: A binary variable that is “1” if all routes pass through link l included in LKj, and “0” otherwise.
Obj: The probability that the original content will be leaked due to eavesdropping on m links.

  The constraint equations in the third integer programming are the following equations (14) to (16), which are the same as the constraint equations (7) to (9) of the path conservation law in the second integer programming: .

  In the third integer programming method, the condition that m of the k routes are link-independent is given by the following equation (17).

  Furthermore, in the present embodiment, the following equation (18) is given as a condition for a route to pass through a link set that is wiretapped. Further, the following equation (19) is given as a condition that all routes pass through the link set to be wiretapped.

  Then, when all routes pass through at least one of the m links eavesdropped, the original content leaks. Since the object of the present invention is to minimize such a probability, the objective function to be minimized is given by the following equation (20).

  According to the present embodiment, the partial content that maximizes the number of links that can restore the original content c when eavesdropped, and minimizes the probability that all such links are actually eavesdropped. cp delivery route can be determined. Therefore, even when the partial content cp that is secretly distributed and held by a plurality of nodes is distributed via a route including a link that may be eavesdropped, secure content distribution can be performed.

  In the first embodiment described above, it is assumed that partial content cp in the middle of distribution may be eavesdropped on the link. However, it is assumed that partial content cp in the middle of distribution may be eavesdropped on the relay node. However, by replacing the link-independent route with a node-independent route, the distribution route of each partial content can be determined in the same procedure.

  That is, in the second embodiment of the present invention, arbitrary k pieces of n pieces of partial content cp secretly held by U pieces of delivery source nodes 1 are delivered to the delivery destination node 2 via the network 3. Assuming that there is a possibility that partial content cp in the middle of delivery may be wiretapped at a relay node on the route, there is a route that minimizes the probability that all k partial content cp will be wiretapped. It is determined.

FIG. 5 is a flowchart showing the operation of the present embodiment. In step S21, the topology (N, Link) of the network 3 is acquired by the topology acquisition unit 101. In step S22, the maximum number m of node-independent paths that do not include a common node among the many paths from the U distribution source nodes 1 to the distribution destination node 2 that hold the partial content cp is It is obtained by solving the integer programming method of 4. In the fourth integer programming method, constants are defined as follows:

N: A set of nodes constituting the network.
n: Node.
NC: A set of nodes holding partial contents.
c: Node holding partial content.
d: Distribution destination node.
L: A set of links that make up the network.
l: Link.

In addition, variables are defined as follows.

xl: A binary variable that is “1” if a node-independent path passes through link l and “0” if it does not pass.
M: Number of node independent paths.

  In the fourth integer programming, the constraint equations related to the path conservation law are given by the following equations (21) to (25). Further, the following equation (26) is given as a condition that each path is node-independent.

  Since the objective function to be maximized is the variable M, in this step S22, the maximum number m of node-independent paths is obtained by solving the fourth integer programming.

  In step S23, the maximum number m of node-independent paths is compared with the threshold value k. If the maximum number m is greater than or equal to k, the process proceeds to step S24 in order to distribute k partial contents by selecting k paths from m node independent paths. Thus, the attacker cannot restore the original content c unless eavesdropping on at least k relay nodes.

In step S24, node-independent k routes for distributing each partial content cp are determined so that the probability that all the k relay nodes are wiretapped and the original content c leaks is minimized. Here, k paths are determined by solving the fifth integer programming method described in detail below. In the fifth integer programming method, constants are defined as follows.

N: Set of nodes constituting the network
n: Node
NC: A set of nodes holding partial contents
c: Node holding partial content
d: Delivery destination node
L: Collection of links that make up the network
l: Link
NK: A set of k relay node combinations that are eavesdropped
NK j: Set of relay nodes included in jth combination in NK
P j: Probability that all relay nodes included in NK j will be wiretapped
nin: A set of links that end at node n
nout: A set of links starting from node n

The variables are defined as follows:

Xl (i): A binary variable that is “1” if the i (1 to k) th route passes through link l and “0” if it does not pass.
Yj (i): A binary variable that is “1” if the i (1 to k) th route passes through a relay node included in NKj, and “0” if it does not pass.
Zj: A binary variable that is “1” if the entire route passes through the relay node included in NKj, and “0” otherwise.
Obj: Probability of leaking the original content c due to eavesdropping on k relay nodes

  In the fifth integer programming method, the constraint equations of the following equations (27), (28), and (29) are given as path conservation rules. In this embodiment, all routes must be node-independent, and a plurality of routes do not pass through each relay node n. Therefore, the following equation (30) is a node-independent condition.

  Furthermore, in the present embodiment, the following equation (31) is given as a condition for a route to pass through a set of relay nodes that are wiretapped. Further, the following expression (32) is given as a condition that all routes pass through a set of eavesdropping relay nodes.

  In the present embodiment, the original content c is leaked when all routes pass through at least one relay node among the k relay nodes that are eavesdropped. Since the purpose of this embodiment is to minimize such a probability, the objective function to be minimized is given by the following equation (33). In this embodiment, the probability that each relay node n is eavesdropped is known, and the probability Pj is calculated based on the eavesdropping probabilities of all relay nodes n included in LK j, for example, as the product of each eavesdropping probability. .

  In this step S24, k routes independent of nodes to which each partial content cp is to be distributed are determined from the value of Xl (i) obtained by solving the fifth integer programming.

  On the other hand, if it is determined in step S23 that the maximum number m of node-independent paths is smaller than the required number of paths k, the process proceeds to step S25. In this case, the attacker may be able to restore the original content c only by eavesdropping m relay nodes that are fewer than k. However, if the k routes for distributing the partial content include m node-independent routes, the attacker cannot restore the original content c only by eavesdropping on m−1 nodes.

  Accordingly, in this step S25, the partial content cp is included so that the probability that the original content c is leaked by including m (<k) node-independent paths and eavesdropping on the m relay nodes is minimized. K routes for distribution are determined.

In the present embodiment, such k paths are determined by solving a sixth integer programming method described in detail below. The constants in the sixth integer programming are defined as follows.

N: Set of nodes constituting the network
n: Node
NC: A set of nodes holding partial contents
c: Node holding partial content
d: Distribution destination node
L: Collection of links that make up the network
l: Link
NK: A set of combinations of m relay nodes eavesdropped
NKj: Set of relay nodes included in the jth combination in NK
P j: Probability that all relay nodes included in NKj will be wiretapped
nin: A set of links that end at node n
nout: A set of links starting from node n

The variables are defined as follows:

Xl (i): A binary variable that is “1” if the i (1 to k) th route passes through link l and “0” if it does not pass.
Yj (i): A binary variable that is “1” if the i (1 to k) th route passes through a relay node included in NKj, and “0” if it does not pass.
Zj: A binary variable that is “1” if the entire route passes through the relay node included in NKj, and “0” otherwise.
Obj: Probability of leaking the original content due to eavesdropping on m relay nodes

  The constraint equations in the sixth integer programming are the following equations (34) to (36), which are the same as the constraint equations (27) to (29) of the path conservation law in the fifth integer programming. .

  In the sixth integer programming method, the condition that m paths out of k paths are node-independent is given by the following equation (37).

  Furthermore, in the present embodiment, the following equation (38) is given as a condition for a route to pass through a set of relay nodes that are wiretapped. Further, the following equation (39) is given as a condition that all routes pass through a set of relay nodes that are wiretapped.

  Then, when all routes pass through at least one relay node among the m relay nodes to be wiretapped, the original content leaks. Since the object of the present invention is to minimize such a probability, the objective function to be minimized is given by the following equation (40).

  According to the present embodiment, a portion that maximizes the number of relay nodes that can restore the original content when eavesdropping, and minimizes the probability that all such relay nodes are actually eavesdropped. Content distribution route can be determined. Therefore, even when partial content that is secretly distributed and held by a plurality of distribution source nodes is distributed via a node that may be wiretapped, safe content distribution is possible.

  In each of the above embodiments, the present invention has been described by taking content distribution using (k, n) threshold secret sharing as an example. However, the present invention is not limited to this, and each link on the route or Considering the probability that partial content is eavesdropped on each node as the failure probability of each link or each relay node, it is more reliable when delivering the same k pieces of content from U nodes to the destination node. High k paths can be determined.

  In other words, in redundancy in which a plurality of identical data is distributed to a single destination node, the probability that all k paths will fail due to multiple link failure or multiple node failure and content distribution cannot be performed is minimized. Since the delivery route can be determined, highly reliable redundancy is possible.

DESCRIPTION OF SYMBOLS 1 ... Distribution origin node 2 ... Distribution destination node 3 ... Network 4 ... Distribution route determination server

Claims (5)

Distribution route determination for a content distribution system that divides the content to be distributed into multiple partial contents, distributes them to distribution source nodes on the network, and distributes each partial content from each distribution source node to the distribution destination node via multiple routes In the device
Means for calculating the maximum number m of link-independent paths from each distribution source node to the distribution destination node based on the network topology;
A first determining means for determining k paths from the m link-independent paths when the number k of partial contents to be distributed to the distribution destination node is the maximum number m or less;
A second determining means for determining k paths including the m link-independent paths when the number k of partial contents to be distributed to the distribution destination node is greater than the maximum number m;
Each of the determining means determines a combination of k routes that minimizes the probability that all routes are wiretapped based on the probability that the link of each route is wiretapped. Routing device. Distribution route determination for a content distribution system that divides the content to be distributed into multiple partial contents, distributes them to distribution source nodes on the network, and distributes each partial content from each distribution source node to the distribution destination node via multiple routes In the device
Means for calculating the maximum number m of node-independent paths from each distribution source node to the distribution destination node based on the network topology;
A first determining means for determining k paths from the m node-independent paths when the number k of partial contents to be distributed to the distribution destination node is the maximum number m or less;
A second determination unit that determines k paths including m independent nodes when the number k of partial contents to be distributed to the distribution destination node is greater than the maximum number m;
Each of the determining means determines a combination of k routes that minimizes the probability that all routes are wiretapped based on the probability that a node on each route is wiretapped. Delivery route determination device.   The content to be distributed is divided into n based on the (k, n) threshold secret sharing method, and k of the n partial contents are distributed from each distribution source node without duplication. The delivery route determination apparatus of the content delivery system according to claim 1 or 2. In a distribution route determination device of a content distribution system in which a plurality of identical contents are distributed and distributed to distribution source nodes on a network and each content is distributed from each distribution source node to a distribution destination node by a plurality of routes.
Means for calculating the maximum number m of link-independent paths from each distribution source node to the distribution destination node based on the network topology;
A first determining means for determining k paths from the m link-independent paths when the number k of contents to be distributed to the distribution destination node is equal to or less than the maximum number m;
A second determining means for determining k routes including the m link-independent routes when the number k of contents to be delivered to the delivery destination node is greater than the maximum number m;
Each of the determining means determines a combination of k routes that minimizes the probability that a failure will occur in all the routes based on the probability that a failure will occur in the link of each route. Delivery route determination device. In a distribution route determination device of a content distribution system in which a plurality of identical contents are distributed and distributed to distribution source nodes on a network and each content is distributed from each distribution source node to a distribution destination node by a plurality of routes.
Means for calculating the maximum number m of node-independent paths from each distribution source node to the distribution destination node based on the network topology;
A first determining unit that determines k routes from the m node-independent routes when the number k of contents to be distributed to the delivery destination node is equal to or less than the maximum number m;
A second determining unit that determines k paths including m node-independent paths when the number k of contents to be distributed to the distribution destination node is greater than the maximum number m;
Each of the determining means determines a combination of k routes that minimizes the probability that a failure will occur in all routes, based on the probability that a failure occurs in a node on each route. System for determining the delivery route of the system.

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