JPH04363941A - Eavesdropping prevention method in asynchronous transfer mode communication - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing information eavesdropping on a cell multiplexed line in asynchronous transfer mode communication.

0002

2. Description of the Related Art It goes without saying that it is important to prevent information eavesdropping in a highly information-oriented society. The present invention relates to a method for preventing eavesdropping in asynchronous transfer mode communication in this sense, and will first begin with a brief explanation of asynchronous transfer mode communication. Now, there are two types of time-division multiplexing methods: a method in which multiplexing is performed by identifying a position on the time axis, and a method in which multiplexing is performed by identifying a label. Conventionally, there is a packet method that multiplexes the information field with variable length as a label multiplexing method, but recently, fixed-length packets (
(synchronous transfer mode A)
Synchronous Transfer Mode
(hereinafter abbreviated as ATM) has been proposed. ATM
Since cells are sent only when information transfer is requested, intermittent/continuous communication is possible depending on the frequency, and it can support any transfer speed from low to high speed.
And if there is no information, empty cells are inserted, so
Cells appear at a fixed timing, and the cell head can be identified and replaced at high speed, making it a promising method as a future broadband ISDN transfer mode. In addition, the literature describing ATM includes Kawarasaki et al., "Trends in ATM communication technology--Towards development to high-speed broadband system--", Journal of the Institute of Electronics, Information and Communication Engineers, 71, 8, pp.
．． 809-814 (Sho 63-08).

FIG. 3 is an explanatory diagram showing an international standard ATM cell structure. In the figure, 1 is a cell, 2 is a header, and 3 is a cell.
is the information field, 4 is the virtual path identification (VPI) field, 5 is the virtual circuit identification (VCI) field, and 6 is the other control information field, cell 1 is 53 bytes, header 2 is 5 bytes, information field 3 is 48 bytes, VPI field 4 is 12 bits within the network, user
The data between networks consists of 8 bits, and the VCI field 5 consists of 16 bits. Header 2 contains control information necessary for multiplexing, cell switching, traffic control, etc.

[0004] In a node, header 2 is usually analyzed by hardware to perform multiplexing, cell switching, and traffic control at high speed. One specific channel on the multiplexed transmission path is identified by (VPI+VCI), and VPI and VCI are replaced with new values at the switching node. FIG. 4 is a block diagram showing an example of eavesdropping between nodes.
, 8 is a node, 9 is a transmission line, and 10 is a wiretapping device. Cell 1 is transferred to the transmission line 9. To eavesdrop on a specific channel, it is only necessary to select a cell with a specific VPI and VCI using the eavesdropping device 10, but there is a risk that the eavesdropping can be easily performed. As a conventional technique for preventing wiretapping, a method of encrypting the cell 1 can be considered.

However, in ATM, the transmission speed is several Gb.
It is not feasible to decode the cell and analyze the header 2 at the switching node since speeds up to i/s or higher are assumed. Furthermore, even if only the VPI and VCI are encrypted, the encrypted VPI and VCI are information indicating the destination at the time of exchange at the exchange, and always take the same value during communication, so if you extract the cell with that value, It can be easily eavesdropped.

[0006]

[Problems to be Solved by the Invention] The present invention has been made in view of the above circumstances, and its purpose is to
An object of the present invention is to provide a wiretapping prevention method in asynchronous transfer mode communication that can prevent wiretapping without impairing high speed.

[0007]

[Means for Solving the Problems] In order to solve the above problems, the present invention provides multiple VPs for one call channel.
I,VCI is assigned and the assigned VPI,VCI is
Cells are transferred using any one of them at random.

[0008]

[Operation] The present invention allocates a plurality of VPIs and VCIs to one call channel, and
The most distinctive feature is that cells are transferred using any one of I and VCI at random. Therefore, in the transmission path between the sending node and the receiving node,
Since the VPI and VCI related to the same call channel always change on a cell-by-cell basis, it becomes impossible to collect the communication content of a specific call even if cells with specific VPI and VCI are extracted. Furthermore, even if all cells on the transmission path are collected, it is difficult to extract cells of a specific call, making it possible to prevent eavesdropping. In the present invention, since only the VPI and VCI are changed on a cell-by-cell basis, processing of the header 2 at the sending node and the receiving node is easy, and eavesdropping can be prevented without impairing the high speed of ATM.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described in detail with reference to the drawings. To simplify the explanation, an example will be described in which the present invention is applied only to VCI. FIG. 1 shows an embodiment of a switching node that implements the eavesdropping prevention method of the present invention, with 11
is an incoming transmission line, 12 and 13 are outgoing transmission lines, 14 and 15 are output buffers, 16 and 17 are highways in the switching node,
21 is a header processing circuit, 22 and 23 are memory control circuits,
24, 25 are memories, 26 is a central processing unit, 27 is a random selection circuit, 31, 32 are words of memories 24, 25, 41, 42, 43, 44, 45 are fields of word 32, 51, 52, 53, 54, 55, 56, 57, 5
8 is a control line.

The memory 24 is a memory that takes correspondence between the "incoming VCI" and the "conversion VCI" of cells arriving from the incoming transmission line 11, and converts the converted VC using the incoming VCI as an address.
You can get I. The memory 25 is a memory that corresponds to the “conversion VCI” and “output VCI”, and
The output VCI can be obtained using I as an address. When a cell arrives from the input transmission path 11, the header processing circuit 21
The input VCI is connected to the memory control circuit 22 via the control line 53.
Enter.

The memory control circuit 22 inputs the incoming VCI as an address via a control line 55, reads the converted VCI from the word 31 of the memory 24, and inputs the converted VCI to the memory control circuit 23 via a control line 54. . The memory control circuit 23 inputs the converted VCI as an address to the memory 25 via a control line 57, reads out the output VCI(s) from the word 32, and selects the plurality of output VCIs by the random selection circuit 27 via a control line 58. One out of V
The CI is determined, and the output VCI is returned to the header processing circuit 21 via the control line 54, the memory control circuit 22, and the control line 53, and the header processing circuit 21 replaces the input VCI of the cell with its output VCI, For example, the signal is input to the output buffer 15 via the highway 17. The cell is output buffer 15
The signal is sent out to the output transmission line 13 from there.

[0012] A plurality of cell VCIs for one call are assigned, and this assignment is done by using a call setup control cell from a switching node on the sending side at the time of call setup.
It will notify you that #3, #38, and #74 will be used as CIs. When the header processing circuit 21 analyzes the header and detects a call setting control cell, it transfers the cell to the central processing unit 26 via the control line 51. The central processing unit 26 determines the conversion VCI and the output VCI in addition to controlling the selection of the output route. First, when a free conversion VCI is determined, the conversion VC
In order to write I to the address corresponding to the incoming VCI in the memory 24, the plurality of VCIs designated by the sending exchange node and the converted VCI determined by the central processing unit 26 are transferred to the memory control circuit 22 via the control line 52. .

The memory control circuit 22 writes the converted VCI to a specified address according to the instruction. For example, if the converted VCI is #21, in the above example, the converted VCI #21 is written to addresses #3, #38, and #74 of the memory 24. Therefore, the incoming VCI of the cell of the call is #3,
If it is either #38 or #74, the conversion VCI is #21
will be converted to . At the same time, the central processing unit 26
Multiple vacant output VCIs (e.g. #55, #89, #93
) is determined and the conversion VC of the memory 25 is determined via the control line 56.
In order to write a plurality of output VCIs to the address corresponding to I, the converted VCI and output VCI are transferred to the memory control circuit 23.

The memory control circuit 23 outputs output VCIs (#55, #89, in this example) to addresses corresponding to the converted VCIs.
#93) is written. Specifically, word 3 shown in Figure 2
In fields 41 to 45 of No. 2, write one output VCI per field, such as #55 or #89. In this example, three output VCIs are used, so fields 41, 42, and 43 contain #55, #89, and #9.
3 are written respectively. When the memory control circuit 23 reads the word 32, it inputs a plurality of output VCIs to the random selection circuit 27 via the control line 58, and the random selection circuit 2
7 generates a random number and selects one output VCI from multiple output VCIs.
and control line 58, memory control circuit 23, control line 5
4. The output VCI is returned to the header processing circuit 21 via the memory control circuit 22 and the control line 53.

Therefore, each time word 32 is read, in the above example, one of output VCIs #55, #89, and #93 is randomly selected. Therefore, when a cell for the call arrives from the incoming transmission line 11, the incoming VCI is (
#3, #38, #74 changes in units of cells)
Once converted to conversion VCI #21, output VCI is #55
, #89, or #93. Therefore, the VCI of the call channel flowing through the incoming transmission path 11 and outgoing transmission path 13 is not fixed and constantly changes, making it possible to prevent eavesdropping.

In the above explanation, the assigned VCI, the assigned VCI, and the assigned VCI
Although the number of CIs was several, since the VCI has a capacity of 16 bits, there is no particular restriction on increasing the number of allocated VCIs to several hundred or more. In the above example, the entry V
As CI and outgoing VCI are assigned at the time of call setup,
The multiple VCIs assigned are fixed during communication, but
It is also possible to change this during communication. This can be done by determining a new VCI at the sending node during communication, and at the receiving node, rewriting the contents of the memories 24 and 25 from the central processing unit 26. In this case, the randomness of the VCI increases, so It becomes possible to increase the durability.

[0017] The above explanation is an example in which multiple VCIs are allocated at the time of call setup.
A method may also be used in which a CI allocation group is determined and one VCI in the group is notified to the other node when setting up the call. In the above explanation, the VCI is changed on a cell-by-cell basis, but it is clear that changing the VPI on a cell-by-cell basis, or changing only the VPI, can be achieved using a configuration similar to that shown in FIG. .

In addition to the above embodiment, if a conventional scrambler is applied to the information flowing through the input transmission path 1, output transmission path 13, etc., it is possible to further increase the resistance to eavesdropping. In addition, the VPI assigned from the sending node,
By encrypting the information that notifies the VCI, it becomes possible to further increase the resistance to eavesdropping. In the above explanation, multiple VCIs are used when there are very few special calls.
Although there is a high possibility of eavesdropping even if VCI is used, this can be countered by setting a dummy channel, assigning multiple VCIs to empty cells, etc.

[0019]

As explained above, according to the method for preventing eavesdropping in ATM communication of the present invention, a plurality of VPIs and VCIs for identifying cell multiplexed channels are allocated, and the VP
Since the I and VCI are changed on a cell-by-cell basis, it is impossible to obtain communication information of a specific call even if a specific VPI and VCI are extracted on the transmission path, making it possible to prevent eavesdropping. In addition, since this method changes only the VPI and VCI, the header processing does not become complicated and the circuit configuration can be simplified, and wiretapping prevention can be achieved without impairing the high speed of the ATM.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a configuration example of a word 32 in FIG. 1;

FIG. 3 is an explanatory diagram showing an ATM cell structure.

FIG. 4 is a block diagram illustrating an example of eavesdropping between nodes.

[Explanation of symbols]

1...Cell, 2...Header, 3...Information field, 4...Virtual path identification (VPI) field, 5...Virtual line identification (V
CI) field, 6...information field, 7, 8...node, 9...transmission line, 10...wiretapping device, 11...incoming transmission line, 1
2, 13... Output transmission line, 14, 15... Output buffer, 16
, 17...highway, 21...header processing circuit, 22,2
3...Memory control circuit, 24, 25...Memory, 26...Central processing unit, 27...Random selection circuit, 31, 32...Word, 41, 42, 43, 44, 45...Field, 51
, 52, 53, 54, 55, 56, 57, 58...control line

Claims (1)

[Claims] Claim 1: In asynchronous transfer mode communication, assigning at least one of a plurality of virtual path identifications or a plurality of virtual circuit identifications to a channel of one call, and transferring information of the call. In this case, at least one of the random use of any one of the plurality of virtual path identifications assigned to each cell, or the random use of any one of the plurality of virtual circuit identifications assigned to each cell is carried out. A method for preventing eavesdropping in asynchronous transfer mode communication, the method comprising transmitting cells using asynchronous transfer mode.