JPH01194541A - Cryptographic key communication system - Google Patents

Abstract

PURPOSE:To execute safe secret communication with plural stations by coupling the ID information of the respective stations and the secret information of a system itself. CONSTITUTION:In the case of a star-shaped network to be composed of an (m) number of users, when a user 1 is obtained as the central user of a central station to distribute a communication sentence, the communication sentence is transmitted only with the central user by respective users (i) of respective slave stations. Here, for the procedure of key generation in the user 1 (central user) and users (i) (2<=i<=m), the opened ID information, which is peculiar for the users (i) of the respective stations, the secret information of the system itself and coupling information with a random number are collected from the respective slave stations by the central station and prescribed operation is executed at first. Next, a cryptographic key to be common for the respective stations is made by sending an operated result to the respective slave stations and the communication is executed by using this cryptographic key. Thus, the same secret key is shared by the plural stations and the secret communication can be safely executed.

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a cryptographic key communication system in which secret keys are shared by multiple stations to perform secret communications using secret key cryptography. [Prior art] Figure 3 shows Eiji Okamoto's conventional cryptographic key sharing method (“ID
“Key distribution method based on ”, Institute of Electronics and Communication Engineers Technical Research Report IT
86-53. 'pp, 25-28゜1986) is a configuration diagram showing a device version of the system. In the figure, 51 is a memory for storing secret information, 52 is a memory for storing public information, and 53 is for storing an integer e. A memory 54 is a random number generator, 55 is a memory for storing random numbers generated by the random number generator 54, and 56 is a value S of the secret information memory 51, a value S of the public information memory 52, and a value of the random number storage memory 55. A circuit that calculates s-a'modn from r, 57 is a terminal for outputting a message, 58 is a terminal for inputting a message, 59 is a terminal for a user to manually input the ID information of the other party, 60 is the random number storage mentioned above. From the value r in the memory 55, the value e in the memory 53, the value X input from the correspondence terminal 58, and the information ID input from the ID information input terminal 59, (x''/r D)'
A circuit 61 is a terminal for outputting a key. Next, the operation will be explained. The operator or builder of a network or communication system selects large prime numbers p and q in advance and calculates . = p, q (15
1) Calculate. Also, e-d = 1 (mod (p-1) (q-1) (however, e is coprime to Cp-1) (q-1)")
(152) Select e and d, and from user i's ID information (this is IDi), s i = I Di ' mod n
(153) and stores it in the secret information memory 51 unique to that user. (153) If 2 holds, s i” = ID i (mod n)
(154) (Rivest, R, L, .
Shamir, A., 8dleman, L.: AMet
Hod for Obtaining Digital
Signatures andPublic-key
Cryptosystems”, Commun, A
CM, 21+pp. 120-126.1978), so if this confidential information is sent along with the message, the recipient can confirm it using the sender's ID. In addition, the operator or constructor is CF (
pi, G F (select the integer a that becomes the primitive element with ql,
The information is stored in the public information memory 52. Integer e also memory X53
Store in. When sharing a key between two parties, for example, when user 1 and user 2 share a key, the key generation procedure for user 1 and user 2 is the same, so here we will describe the generation procedure for user 1. . First, the user 1 causes the random number generator 54 to generate a random number r, and stores it in the memory Y55. In the arithmetic circuit X56, the secret information memory 51, the public information memo IJ52, and the memory Y5
5 to x, = s, −a”mod n
(155) is calculated and transmitted to the user 2 from the message output terminal 57. User 2 also sets x2 to user 1.
Send to. Next, user 1 receives the information x2 sent from user 2 from the message input terminal 58. User 1 inputs the ID information of the other user, that is, the ID, to the ID information input terminal 59.
and also memory X. 53 and memory Y55 using the arithmetic circuit Y60.
= (X2 ” / I Dt ) ”mod n
Find (156). User 2 similarly obtains the Key. At this time, the value obtained from the key output terminal 61 is Key=
a “”” mod n (157
), which means that user 1 and user 2 have been able to share the key. [Problem to be solved by the invention] Since the conventional cryptographic key communication method using ID information is configured as described above, the secret key can only be shared in one-to-one communication. When multiple stations communicate at the same time, such as in a TV conference, there are problems such as the need to share the secret key using another method. This invention was made to solve the above-mentioned problems, and by combining the ID information of each station and the secret information of the system itself, it is possible to carry out secure secret communication between multiple stations using cryptographic key communication. The purpose is to obtain a method. [Means for Solving the Problems] The cryptographic key communication method according to the present invention allows a central station to collect combination information of ID information that is unique to users of each station and is made public, secret information of the system itself, and random numbers. The data is collected from each slave station, subjected to a predetermined calculation, and the result of this calculation is sent to each slave station to create an encryption key common to two or more stations, and this encryption key is used to perform communication. It is something. [Operation] Each slave station uses TD, which is disclosed as information unique to the user.
The information, a combination of secret information of the system itself and random numbers, is sent to a central station. The central station performs predetermined calculations on the combination information collected from each slave station and sends the result to each slave station. As a result, an encryption key common to each slave station is passed to each slave station. Each slave station communicates with the central station using this common encryption key. [Embodiment of the Invention] An embodiment of the invention will be described below. FIG. 1 shows an embodiment of the present invention. In the figure, 1 is a memory for storing secret information, 2 is a memory for storing public information, and 3 is a memory for storing public information.
is a random number generator, 4 is a memory for storing random numbers generated by this random number generator 3, and 5 is a value S of the secret information memory 1, a value a of the public information memory 2, and a value r to s of the random number storage memory 4. -a'modn calculation circuit, 6 is a selector with two manual outputs, 7 is a terminal for switching between the general user of the slave station and the central user of the central station, and 8 is one of the selectors 602 and 1 output. Line 9 is this line 8 and the other line,
ID is a terminal for outputting a message, 11 is a terminal for inputting a message, 12 is a gate that opens when a central user is designated with the general user/central user switching terminal 7, and 13 is a gate for the general user/central user. A gate that opens when a general user is specified at the central user switching terminal 7, 14 is a line exiting from the gate 12, and 15 is a line from the value X input from the correspondence terminal 11 and the ID information ID to x'/I. D”ll1od
16 is a terminal where the user inputs the other party's ID information, 17 is m-1 values)'2+y3
＋・−・. Value S of secret information memory 1, value r of memory 4, and calculation circuit 1
5)' 2 + 13 r '-'+
'/ m and the value 2 obtained by the calculation circuit 17 = Σyi
From Q 2 s ・(z-yz) rmod n, s ・(z・y*
) ' mod n, -. A circuit 19 calculates s-a ``mod n'' from the value S of the secret information memory 1, the value a of the public information memory 2, and the value r of the memory 4.
20 is a combiner that combines the calculation result of the calculation circuit 18 and the calculation result of the calculation circuit 19; 21 is the calculation result 2 of the calculation circuit 17 and the value r to z of the memory 4;
22 is a selector for 2-manpower l output, 23 is one line of the 2-manpower of this selector 22, 24 is this line 23 and the other line, 25
is a line coming out from the gate 13, 26 is a separator that separates the combined values input from the correspondence terminal 11, 27 is one line of the two outputs of this separator 26,
28 is this line 27 and the other line, 29 is the value r of the memory 4 and the ID input from the ID information input terminal 16.
One value z1 of the two divided values is inputted together with the ID via the information 1g ID and the separator 26, and then sent to the arithmetic circuit 15.
From the value W outputted in and the other value 2 divided into two, (
z'/ID")/w' mod n calculation circuit,
30 is a terminal from which a key is obtained when the key sharing procedure is completed. Next, the operation will be explained. The operator or builder of a network or communication system must determine in advance the large prime numbers p+, pz (where p i =4k i-1, i=
1.2), n=p+ pz, (ID
1) k = 2 k + ・kz k+ kz+
1 (ID2) is calculated. Then, from the ID information of user i (this is referred to as IDi), s i = T Di ' mod n
(ID3) and stores it in the secret information memory 1 unique to that user. If the formula (ID3) holds, s i' = IDi” (mod n)
(ID4) (Lieb
erherr, K, :Uniform Compl
Exity and Digital Signatu
1. Notes in Compute
r 5science 115+＾utoma. Language and programming,
Eighth ColloColloquiu, l5
Rael, pp. 530-543+ 1981), so if this secret information is sent along with the message, the receiver can confirm the sender's [D]. In addition, the operator or constructor is GF (p+), GF (1)z
) is used to select an integer a as a primitive element and store it in the public information memory 2. In the case of a star-shaped network consisting of m users as shown in Figure 2, user 1 is connected to the central station that collects and delivers messages.
"Central user", each user of each slave station communicates messages only with the central user. The key generation procedure is the same for all users except for the central user (since it is the same for all users, here we will explain the steps for user I (central user) and user i).
The procedure for (2≦i≦m) will be described. In FIG. 1, user i first generates a random number ri using random number generator 3 and stores it in memory 4. In the arithmetic circuit A5, from the secret information memory 1, the public information memory 2, and the memory 4, x i = s i-a” mod n
(ID5) is calculated and sent to selector A6. The selector 86 is connected to the general user/central user switching terminal 7, and selects line A8 for the general user and line B9 for the central user, and outputs the selected line to the message output terminal ID. Since user i is a general user, it outputs the value of formula (ID5) and sends it to user 1 (central user). Next, user 1 receives xi from user i. Similarly, each user receives xZ+ x3+...-'+ x
Receive i-1, x tit, -1xm. These are inputted from the correspondence human power terminal 11. Gate A12 is open only when the central user is present, and gate B13 is open only when the user is a general user. Send to B15. User 1 inputs from the ID information input terminal 16, if x2, IDZ + if Xi, ID3, '-"+
When xm, input IDm manually and use arithmetic circuit B15 to calculate 1 z=xz'/IO, 2mod n= a ""
mod n2=Σ y i mod n=a' ””r
Find 3+G-""modn. Furthermore, the arithmetic circuit D18 is used to calculate from the values of the secret information memory 1, memory 4, equations (ID6), and equations (ID7). Furthermore, using the arithmetic circuit E19, z I=s
, -a4r'mad n (ID9
), and user 1 sends (Z 2+ Z +
) + To user 3 (zff + z +) + '-' * To user m (zz, zυ are output from the message output terminal 11 via the coupler 20. At the same time, the user 1
Using memory 4 and the value of formula (ID7), Key = z”'mod n
Find (1 ID). Selector B22 outputs line E23 when the user is a central user, and outputs line F24 when the user is a general user. Here, the value of equation (1ID) is selected and output from the key output terminal 30. On the other hand, user i receives (zLz+
) and enter gate B13. It is sent to the separator 26 via line D25. Separator 26 connects zi to line G27
．． 2. are divided and sent to line H28. 2. ID of the other party inputted from the ID information input terminal 16, that is, ID; Using the arithmetic circuit B15, w = z, '/ ID, " mod n
(111), and furthermore, IDI and W
21 and the value of memory 4, use the arithmetic circuit G29 to calculate Key = (zi'/!D+")/wi"mod n
(112) is obtained from the key output terminal 30. At this time, Key=a16rl +rz+r:+,-,,+rn
) modn(l13) holds, all users can obtain the same Key value. [Effects of the Invention] As explained above, the present invention allows a central station to transmit to each user a combination of ID information, private information, and random numbers, which is unique to the users of each station, and random numbers. A common encryption key is created for each station by collecting data from the station, performing a predetermined calculation, and sending the results of this calculation to each slave station.This encryption key is used for communication, so secret communication between two or more stations is possible. This has the effect of allowing multiple stations to share the same secret key even when doing so.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an encryption key communication method according to an embodiment of the present invention, FIG. 2 is a configuration diagram of a star network to which this invention is applied, and FIG. 3 is a configuration diagram showing a conventional encryption key communication method. It is a diagram. 1 is a secret information memory, 2 is a public information memory, 3 is a random number generator, 4 is a memory, 5 is an arithmetic circuit A, 6 is a selector A,
7 is general user/central user switching terminal, 8 is line A,
9 is a line B, ID is a message output terminal, 11 is a communication human power terminal, 12 is a gate A, 13 is a gate B, 14 is a line C115 is an arithmetic circuit B, 16 is an ID information input terminal, 1
7 is an arithmetic circuit C, 18 is an arithmetic circuit D, and 19 is an arithmetic circuit E.
, 20 is a coupler, 21 is an arithmetic circuit F, and 22 is a selector B.
123 is line E, 24 is line F, 25 is line D1
26 is a separator, 27 is line G128 is line H129
51 is a secret information memory, 52 is a public information memory, 53 is a memory x 154 is a random number generator, 55 is a memory Y 156 is an arithmetic circuit x 157 is a message output terminal, 58 is a message output terminal, and 58 is a message output terminal. Terminals 60 are an arithmetic circuit Y, 59 is an ID information input terminal, and 61 is a key output terminal. Agent Masuo Oiwa (2 idiots) Taku 1+”
U Figure 2 Collection 3 59; TDJtiu77GJ, 67, "gL'7j"
Ph”r procedural amendment (spontaneous) 1. Indication of the case Patent Application No. 1983-018051 2.
Name of the invention Encryption key communication method 3, Person making the amendment Representative Moriya Shiki 4, Agent 5 Full text of the specification to be amended. a. Contents of the amendment The entire text of the specification shall be amended as shown in the attached sheet. Above description (full text amended) 1. Title of the invention Encryption key communication method 2. Claims On a communication path that constructs a network system in which a central station and a plurality of slave stations are connected in a star shape. , when each station performs secret communication using a common encryption key,
Encryption key communication in which the encryption key common to each station is created by calculating the secret information of the system itself, the public ID information such as the user name of each station, and a random number, and communication is performed using this common encryption key. A method in which a central station collects combination information consisting of a combination of ID information disclosed to each station, the above-mentioned secret information, and the above-mentioned random number from each slave station, performs a predetermined calculation, and sends it to each slave station. A cryptographic key communication system characterized by creating a common cryptographic key for two or more stations and performing secret communication using this cryptographic key. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a cryptographic key communication system in which a secret key is shared by a plurality of stations for secret communication using secret key cryptography. [Prior art] Figure 3 shows the conventional cryptographic key sharing method (“ID
``key distribution method based on ``, Institute of Electronics and Communication Engineers Technical Research Report IT
86-53. pp. 25-28゜1986). In the figure, 51 is a memory for storing secret information, 52 is a memory for storing public information, and 53 is a memory for storing an integer e. , 54 is a random number generator, 55 is a memory for storing random numbers generated by the random number generator 54, and 56 is a value S of the secret information memory 51, a value a of the public information memory 52, and a value r of the random number storage memory 55. 57 is a terminal for outputting the message, 58 is a terminal for inputting the message, 59 is a terminal for the user to input ID information of the other party, 60 is the random number storage memory mentioned above. From the value r of 55, the value e of memory 53, the value X input from the correspondence terminal 58, and the information ID input from the ID information input terminal 59, (x@/ID) 'mo
A circuit for calculating dn, 61 is a terminal for outputting a key. Next, the operation will be explained. The operator or builder of a network or communication system selects a large prime number P+ q in advance and calculates n=P”I (151)
Calculate. Also, e-d mi 1 (mod (p-1) (q-1) (however,
e is relatively prime to (p-1)(q-1))
(152) Select e and d, and from user i's ID information (this is assumed to be ID), St == ID, dmod n
(153), and the user's unique secret information memory 5
Store to 1. If the formula (153) holds, s t e = ID t (mod n)
(154) becomes (
Rivest, R.L., Shamir, A., Adl.
Eman, L.: AMethod for Obta
ining Digital Signatures
andPublic-key Cryptosystem
ms'', Common, ACM, 21.pp. 120-126.1978), so if the message is multiplied with this secret information and sent, the receiver can confirm it using the sender's ID. The person is GF (
Pl, G Ff (Choose the integer a that becomes the primordial light in 11,
The information is stored in the public information memory 52. Integer e also memory X53
Store in. When sharing a key between two parties, for example, when user 1 and user 2 share a key, the key generation procedure for user 1 and user 2 is the same, so here we will describe the generation procedure for user l. . First, the user 1 causes the random number generator 54 to generate a random number r1 and stores it in the memory Y55. In the arithmetic circuit X56, the secret information memory 51, the public information memory 52, and the memory Y55
From xt = s, see a”mod n
(155) and sends the message output terminal 57 to user 2.
Send to. User 2 similarly sends x2 to user 1. Next, the user 1 receives the information X sent from the user 2 from the correspondence terminal 58. User 1 inputs the ID information of the other user, that is, ID2, to the ID information input terminal 59.
, and using the arithmetic circuit Y60 from memory X53 and memory Y55, Key== (x2 e/ I D2
) ” mod n (158) is obtained. User 2 similarly obtains the Key. At this time, the value obtained from the key output terminal 61 is Key=
a' ”r2nod n (15
7), which means that user 1 and user 2 were able to share the key. [Problems to be Solved by the Invention] Since the conventional cryptographic key communication method using ID information is configured as described above, the secret key can only be shared in one-to-one communication. When multiple stations communicate at the same time, such as in a TV conference, there are problems such as the need to share the secret key using another method. This invention was made to solve the above-mentioned problems, and by combining the ID information of each station and the secret information of the system itself, it is possible to carry out secure secret communication between multiple stations using cryptographic key communication. The purpose is to obtain a method. [Means for Solving the Problems] The cryptographic key communication system according to the present invention allows a central station to collect combination information of ID information that is unique to users of each station and is made public, secret information of the system itself, and random numbers. The data is collected from each slave station, subjected to a predetermined calculation, and the result of this calculation is sent to each slave station to create an encryption key common to two or more stations, and this encryption key is used to perform communication. It is something. [Each slave station has an ID that is published as information unique to the user.]
The information, a combination of secret information of the system itself and random numbers, is sent to a central station. The central station performs predetermined calculations on the combination information collected from each slave station and sends the result to each slave station. As a result, an encryption key common to each slave station is passed to each slave station. Each slave station communicates with the central station using this common encryption key. [Embodiment of the Invention] An embodiment of the present invention will be described below. FIG. 1 shows an embodiment of the present invention. In the figure, 1 is a memory for storing secret information, 2 is a memory for storing public information, and 3 is a memory for storing public information.
is a random number generator, 4 is a memory for storing the random numbers generated by this random number generator 3, and 5 is a value s from the value S of the secret information memory 1, the value a of the public information memory 2, and the value r of the random number storage memory 4. -a'modn calculation circuit, 6 is a 2-man power, 1 output selector, 7 is a terminal for switching between the general user of the slave station and the central user of the central station, 8 is the 2-man power of the selector 6. One line, 9 is this line 8 and the other line,
ID is a terminal for outputting a message, 11 is a terminal for inputting a message, 12 is a gate that opens when a central user is designated with the general user/central user switching terminal 7, and 13 is a gate for the general user. /A gate that opens when a general user is specified at the central user switching terminal 7, 14 is a line exiting from the gate 12, 15 is a value x input from the correspondence terminal 11 and the ID information x' / A circuit for calculating ID2mod n, 16 is a terminal for the user to input the other party's ID information, 17 is m-1 values 3/2 + '/s t
.... A circuit 18 calculates eyz from y, and a calculation circuit 17 calculates the value S of the secret information memory 1, the value r of the memory 4, the value 'j21 y3 t..., y, found in the calculation circuit 15, and the calculation circuit 17. From the value z = XZ yt, 7=2 s'(z+y2)' mod n, s'(z″y,
) ' mod n, -. A circuit 19 calculates s-a ``mod n'' from the value S of the secret information memory 1, the value a of the public information memory 2, and the value r of the memory 4.
20 is a combiner that combines the calculation result of the calculation circuit 18 and the calculation result of the calculation circuit 19; 21 is a combiner that combines the calculation result Z of the calculation circuit 17 and the value r of the memory 4 to z;
22 is a selector with 2 human power and 1 output, 23 is one line of the 2 human power of this selector 22, 24 is this line 23 and the other line, 25
is a line coming out from the gate 13, 26 is a separator that separates the combined values input from the correspondence terminal 11, 27 is one line of the two outputs of this separator 26,
28 is this line 27 and the other line, 29 is the value r of the memory 4 and the ID input from the ID information input terminal 16.
One value 2 of the two values divided through the information ID and the separator 26. is input together with the ID, and from the value W outputted by the arithmetic circuit 15 and the other value 2 divided into two, (Z'
/ID2)/w' mod n calculation circuit, 30
is the terminal from which the key is obtained when the key sharing procedure is completed. Next, the operation will be explained. The operator or builder of a network or communication system determines in advance a large prime number p1. P2 (However, pt=4kt −1, i=1.
2), n=p, ・P 2 (I
D1) k=2, ・kz −kl− 2+1
(ID2) is calculated. Then, from the ID information of user i (this is referred to as ID+), s, = IDt ' mod n
(ID3), and secret information memory 1 unique to that user.
Store it in (ID3) If the formula holds, 81 'E”ID+ 2(mad n)
(ID4) (Lieb
erherr, K, :Uniform Compl
Exity and Digital Signatu
re”. Lecture Notes in Computer
5science 115. Automa. Language and programming,
Eighth ColloColloquiu, l5
Rael, pp. 530-543.1981), so if this confidential information is sent along with the message, the recipient can confirm it using the sender's ID. In addition, the operator or constructor is GF (p 1) t GF (p 2)
The integer a that becomes the primitive light is selected and stored in the public information memory 2. In the case of a star-shaped network consisting of m users as shown in Figure 2, user 1 is connected to the central station that collects and delivers messages.
"Central user", each user of each slave station communicates messages only with the central user. The key generation procedure is the same for all users except the central user, so here we use user 1 (central user) and user i (2
≦i≦m) will be described. In FIG. 1, user i first generates a random number ri using random number generator 3 and stores it in memory 4. In the arithmetic circuit A5, the secret information memory 1, the public information memory 2, and the memory 4 are
(ID5) and sends it to selector 86. Selector A6 is connected to general user/central user switching terminal 7,
A general user selects line A8, and a central user selects line B9 and outputs it to the message output terminal ID. Since user i is a general user, it outputs the value of formula (ID5) and sends it to user 1 (central user). Next, user 1 receives X from user i. Similarly, from each user, X2 + X3 +...yXt-
1tXi-1v...,X is received. These are inputted from the correspondence human power terminal 11. Gate A12 opens only for central users, and gate B13 opens only for general users. Therefore, user 1 receives X via line C14.
2 v X3 r..., sends Xo to the arithmetic circuit B15. User 1 inputs ID2.x from the ID information input terminal 16. If x3, then 3,...,X, then I
D, and using the arithmetic circuit B15, z=yt mod n=a ” r2” '←--
--” ” ' Find mod n1=2. Furthermore, secret information memory 1 and memory 4 (
From the values of formulas ID6) and (ID7), calculation circuit D18
Calculate using . Also, using the arithmetic circuit E19, z, =s
, 6a ""mod n (ID9
), and user 1 sends (Zl , zl L
To user 3 (Zl, ZI L”' rTo user m (Z
m +21) through the coupler 20 to the message output terminal 1.
Output from 1. At the same time, user 1 uses arithmetic circuit F21 to calculate ey = z 4''nod n from memory 4 and the value of formula (ID7).
Find (1 ID). Selector B22 selects line E23 when the user is a central user, and selects line F24 when the user is a general user.
Output. Here, the value of equation (1ID) is selected and output from the pair output terminal 3o. On the other hand, user i sends (ZttZ
i) and enter gate B13. It is sent to the separator 26 via line D25. Separator 26 connects Zt to line G
27. z, is divided and sent to line H28. ID of the other party input from the ID information input terminal 16, that is, ID, and Z
From l, using the arithmetic circuit B15, w = z 1 ' / IDt 2mod n
(111), and further, ID, W and z
Using the arithmetic circuit G29 from l and the value of memory 4, Key=(z, '/ID, ')/w, " ma
d n (112) is obtained from the pair output terminal 3o. At this time, Tl, 8y= 816 rs (r2- rs
−−−−−−r, + l ff1od n
Since (l13) holds true, all users can obtain the same Key value. [Effects of the Invention] As explained above, the present invention allows a central station to collect combination information of ID information, which is information unique to users of each station and made public, secret information of the system itself, and random numbers, from each slave station. They are collected, subjected to a predetermined calculation, and the results of this calculation are sent to each slave station to create a common encryption key for each station.This encryption key is used for communication, allowing secret communication between two or more stations. This has the effect of allowing multiple stations to share the same secret key even in the case of multiple stations.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an encryption key communication method according to an embodiment of the present invention, FIG. 2 is a configuration diagram of a star network to which this invention is applied, and FIG. 3 is a configuration diagram showing a conventional encryption key communication method. It is a diagram. 1 is a secret information memory, 2 is a public information memory, 3 is a random number generator, 4 is a memory, 5 is an arithmetic circuit A, and 6 is a selector A
, 7 is general user/central user switching terminal, 8 is line A
, 9 is a line B, ID is a message output terminal, 11 is a communication human power terminal, 12 is a gate A, 13 is a gate B, 14 is a line C115 is an arithmetic circuit B, 16 is an ID information input terminal,
17 is an arithmetic circuit C118 is an arithmetic circuit D, 19 is an arithmetic circuit E, 20 is a coupler, 21 is an arithmetic circuit F, 22 is a selector B, 23 is a line E, 24 is a line F, 25 is a line D
, 26 is a separator, 27 is line G, 28 is line H12
9 is an arithmetic circuit G, 30 is a pair output terminal, 51 is a secret information memory, 52 is a public information memory, 53 is a memory X, 54 is a random number generator, 55 is a memory Y, 56 is an arithmetic circuit X, 5
7 is a message output terminal, 58 is a message human power terminal, 59 is an I
D is an information input terminal, 60 is an arithmetic circuit Y, and 61 is a pair output terminal.

Claims (1)

[Claims] When each station performs secret communication using a common encryption key on a communication path that constructs a network system in which a central station and multiple slave stations are connected in a star shape,
Encryption key communication in which the encryption key common to each station is created by calculating the secret information of the system itself, the public ID information such as the user name of each station, and a random number, and communication is performed using this common encryption key. A method in which a central station collects combination information consisting of a combination of ID information disclosed to each station, the above-mentioned secret information, and the above-mentioned random number from each slave station, performs a predetermined calculation, and sends it to each slave station. A cryptographic key communication system characterized by creating a common cryptographic key for two or more stations and performing secret communication using this cryptographic key.