JPH0389737A - Hierarchical key management system - Google Patents

Abstract

PURPOSE: To establish secret protection between terminal users by providing the system with plural key permission authority means, corresponding to user groups and a terminal means groups and a key permission center means for applying authority to each of the key permission authority means and permitting direct secret protection communication between the terminals of different groups. CONSTITUTION: A terminal group in the hierarchical key management system corresponds to one of user groups, and a large number of users can execute secrecy protective communication with other users by respective terminals SWT through a public exchange telephone network. The system has plural key permitting authorities(KCAs), and each KCA permits a user in a certain group to use a terminal for executing secrecy protective communication with another user in the same user group. The system has also key permission centers(KCCs), and each KCC is connected to plural KCAs to provide permission authority to each KCA and permit secret protection communication between different user groups. Consequently direct secrecy protection between terminal users can be established.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to secure telecommunications systems and, more particularly, to scalable telecommunications systems that support authorized representatives to authorize and authenticate users. Regarding a hierarchical key management system.

(Prior Art) A typical key management system is disclosed in U.S. Patent No. 4,5γ8.
No. 531. The present invention discloses a key distribution system connected to each of a plurality of secure terminals. If secure data transmission is desired, each terminal must establish communication with a key distribution center. The key distribution center then performs terminal qualification checks and performs the necessary security analysis.

A disadvantage of this system is that the key distribution center has to be involved in each secure communication between every two terminals. Terminals exchange security packets of their information only via the key distribution center. Each terminal must send authorization information to the key distribution center for verification and receive the resulting information from the key distribution center. Such multiplex communication is not efficient.

In general, the systems described above do not have hierarchical security. Since all important key data is centralized at the center, if the security of the key distribution center is compromised, the security of each user is also compromised.

It is therefore an object of the invention to provide a hierarchical key distribution system that allows security to be established directly between terminal users.

(Means for Solving the Problems) A novel hierarchical key distribution system is shown in which the objects of the present invention are achieved.

A hierarchical key management system allows multiple users to securely communicate over the public switched telephone network. Hierarchical key management systems assign users to defined user groups.

The hierarchical key management system includes a group of terminals. Each terminal group corresponds to one group of users. Depending on each terminal,
It allows multiple users to conduct secure communications with other users over the public switched telephone network.

A hierarchical key management system has multiple key certification authorities.
property: KCA). This key authorization authority authorizes users of the user group to use the terminal to conduct secure communications with other users of the user group.

The hierarchical key management system also includes a key authorization center. Each key authorization center is connected to a plurality of key authorization authorities. The key authorization center provides authorization authority to each key authorization authority and provides a means to authorize secure communications between different user groups.

(Example) FIG. 1 shows the hierarchy of a key management system. key certification center
er: K CC> is the central authority of this system. KCC provides keyboards, display terminals, hard disks, backup tape streamers, printers, and communication interface terminals (net-wo).
rk1interface terminal:
It is possible to configure a dedicated special purpose computer system with N I T >. N.I.
T is explained below.

Each KCA and KCC has a modem that provides high speed telephone connectivity to the KCA and KCC via the public switched telephone network. It is also possible to use other communication means. The three KCAs are Regional Authority A, Regional Authority B, and Regional Authority C shown in FIG. However, it is also possible to connect four or more KCAs to a KCC.

Each KCA also has a computer with a keyboard, display terminal, hard disk, backup tape streamer, printer, and communication interface terminal.
Consists of systems. Each regional authority i.e. K
CAs can handle more than 500 users, but typically provide secure communications between up to 500 users. For example, regional authority A enables secure communications between users of user group A.

Each user group A, B, and C typically has up to 500 secure wire terminals.
ine terminal: SWT). A user is an individual authorized to use one or more SWTs within a user group.

Each SWT generates an asymmetric key for the secure exchange of traffic keys. The SWT is a security actuator for terminal access and user security.
activation device: S A D
). This SAD is a physical key that is first programmed by the KCA and then reprogrammed by the SWT. This SAD is inserted into the SWT's outlet to allow secure communication and user authorization.

This SWT generates a unique asymmetric-pair encoding/decoding key for each user. This asymmetric key pair is authorized by the Regional Authority (KCA).2
In a large communication system with more than one KCA, users belonging to one user group may wish to make calls with users from other user groups. In this case, users making calls between groups must use a common KC
Must be authorized by a KCA registered with C.

If a user's local authority (KCA) is out of service for a period of time, the KCC can back up all KCAs that are out of service.

This is done by loading the backup tape to the out-of-service KC into the KCC.

Initially, a user of secure communications is seeded 5AD by its Regional Authority (KCA).
), and the corresponding password will be issued. This seed SAD gets its name from being the first or initial SAD from which security information about the individual user is generated. This seed S edge contains data regarding the user's identity and the special code required for authorization.

Users can receive authorization by inserting their SAD into the SWT. Next, if the user attempts to call his regional authority, KCA,
Enter your password. Using this password and password, the user can be authorized in up to eight SWTs.

Roughly, up to eight users can be authorized at each SWT. The number of users per 5WTI and the number of SWTs per user are typically set to 8, but flexibility is provided to increase the number of users per 5WTI and the number of SWTs per user. There is.

Once a user is authorized in a particular SWT, this user can share a common account with other users within the same regional authority or through an automated keying and distribution process performed by linking the two terminals. It is possible to have secure calls with other users who share the KCC. That is, a user belonging to user group 8 can talk to other users belonging to the same group, or a user belonging to group B or a user belonging to group C, and vice versa.

Once a user of SWT receives permission, this user can:
Public switched telephone network (public 5WitChed)
telephone network: PSTN
) or other lines. If it is determined that this call should be a secure call, a security pushbutton on the SWT is pressed. The two SWTs in a particular call exchange authorization data and generate and exchange traffic keys. At this point secure communication is established. As part of this disclosure and security process, authentication information such as the identity of the other party and the security level of the connection is displayed on the SWT.

At the time of user authorization, the KCA adds a termination code to the authorized user's SAD or key. Prior to the termination of this user's SAD, this user
will be notified to re-authorize. For reauthorization, the user must log in to Region K using his password and SAD.
Call CA.

During reauthorization, the terminal generates a new asymmetric encoding/decoding key pair authorized by the KCA and a new termination that is added to the user's SAD and stored. If the user does not reauthorize with the KCA prior to the expiration date, the SWT automatically denies this user access to the system.

The authority is delegated this entire key management system. The KCC and KCA do not have personal keys for each user or SWT. Therefore, if KCA or KCC
If any one of the key management systems is compromised, not all users in the key management system are compromised. However, if the KCC or KCA is compromised, it may give false permissions.

Authority representation is established through a process in which the KCA is registered as an authority with the KCC. This is done using a security process by the PSTN. - Once a degree KC is registered with the KCC, the KCA can issue a registration packet as part of the individual user's authorization process. These registration packets allow users to communicate confidentially with users of other regional authority groups (user groups 8, B or C).

The KCA must perform a reauthorization process to the KCC at regular intervals in order to authorize new asymmetric communication area keys and receive general unauthorized key information. This processing that occurs between the KCA and KCC is similar to the authorization processing that occurs between the SWT and the KCA, except for the content of the message.

The KCC maintains a comprehensive list of unapproved keys.
Authorized key 1st: UK
L) is retained and distributed. This distribution of UKL is done through the hierarchy of the system. KCA represents each of these S
Receive LIKL from WT user. This data, the Lockout packet, is sent to the KCC to update the global UKL.

This global UKL is then passed through KCA to each SWT.
distributed to. Security periods for users on UKL are automatically prevented by SWT. If a KCC is not provided in this configuration, the UKL is stored in the KCA.

From the time the seed SAD is created by KCA, KCA
The key management system monitors, modifies, and is responsible for the use of the applicable SAD until it becomes zero (cleared or set), ie, is gone or expires. When some users are allowed by KCA,
Establishing a secure communication transmission path between two SWTs requires only terminal-to-terminal communication. These communications establish a secure channel between the SWTs. When a user presses the security pushbutton on his or her SWT, a series of messages are exchanged between the SWTs. Some of this exchanged information indicates the channel characteristics of the SWT's modem.

FIG. 2 shows a secure call between SWT user 1A and SWT user 5A. SWT users 18 and 5A
is the authority that makes the same approval, i.e. the second
It is shown as authorized by KCA A shown in the figure. The following description assumes that SWTs 1A and 5A have previously authorized their SAD (Security Executive Device) keys. This is indicated by the lines connecting SWT 1A and 5A@KCAA and by the authorized SAD key. At some point before then, both SWT IA and 5A have performed this authorization process.

SWT IA and 5A have previously established a connection via a telephone line. At this point, the user has STW 1A
Press the security pushbutton. This allows the PSTN
An automatic message exchange is initiated via
240 secured between SWT 1A and 5A
A 0 baud transmission path is established. A 2400 baud transmission line is one example.

The established data transmission path is implemented by the SWT at any data site.

Table 1 below is a roughly 3B list of various encoding and decoding vectors used below.

Table 1 Authorization Encoding Vector Key Authority Authorization Decoding Vector Key Authorization Encoding Vector Key Authorization Decoding Vector User Authorization Encoding Vector User Authorization Decoding Vector Insert into. Initially, the two SWTs exchange access/region messages. These messages contain one authority ID (identification of KCA), version number, terminal data for Dax, central ID (KCC
identification), version number, terminal data for DC, terminal type, and terminal serial number. Both SWTs examine the sent message and try to match it with either the common asymmetric communication area key Dax or DC. A match occurs because both SADs are authorized by the KCA.

Each SWT then sends an authentication packet message (A
Authentication Packet message
age).

This authentication packet/message contains the following information: That is, these are the user's ID signature (l
[) signature: I DS), user's IO,5AD(7)-/'J full number (SAD se
real number: SSN), access information, terminal serial number (Terminal 5eri), access information,
al number: T 3 N ), and the user's authorized asymmetric key EXt.

each SWT receives the other's authentication packet message;
This is decrypted using the common area key [)aX. As a result, each SWT derives the other's asymmetric key Ext. The other user's ID is displayed on the SWT. The displayed ID also indicates the lowest common grade that the two users have. If a significant discrepancy in the access information is discovered, the call will be terminated.

Then each SWT has one random component (RandomC
component: RC>, which are used for keying Kg. One of the copies of the RC is transferred to the regional transmission Kg. The other copy of the RC is encoded using the other user Ext. Each SWT now sends a random component message packet to the other user, which is encoded at the other user EX. When each SWT receives the other's random component message packet, it decodes the packet using [)xt. The random component is and has been used to key the received Kg.

Finally, Crypto sync (Crypto 5sync:
C3) Message packets are generated by each SWT. SWTs 1A and 5A then exchange crypto synchronization (C8) message packets via the PSTN. Each SWT then processes crypto synchronization messages received from other SWTs.

The crypto sync message is processed by the receiving KCI to obtain crypto sync. Once crypto synchronization is achieved,
Each SWT informs its users that a secure transmission path has been established at the appropriate baud rate.

If communication between two SWTs occurs at a 2400 baud rate, the security process described above takes approximately 10 seconds.

To minimize the impact of errors, forward error correction is applied to data exchanges.
) is used.

FIG. 3 describes a secure call from SWT user 1A to SWT user 7B. SWT user 1A is KCA
Permitted by A. SWT user 7B is
Permitted in advance by KCA B. This is between SWT 1A and KCAA and SWT
7B and KCA B, respectively indicated by the dashed line. KCAA and KCA B are key authorization centers (
KCC)X. As mentioned above, SWT 1A and SWT 7B are interconnected via the PSTN in a non-secure manner. S.W.T.
The user of the IA presses the security pushbutton so that the access/region message packet is sent to the SWT IA.
It is transmitted between A and 7B. These access/region messages have KCCIDs and versions, so the access/region message packets match.

Secure calls between SWTs belonging to different KCCs are not allowed under this system.

Since a match is determined by the identity of the KCC rather than the KCA, the next message transmission between SWTs will be different from the common KCA case described above. S in this case
The next message packet transmission between WTs is called a registration packet (Re(7iStratiOnPaCket)). This registration packet consists of the following information:

Namely, these are the granting KCA's non-target domain key (Dax>), the KCA's ID and the access information for each KCA.The entire registration packet is decrypted using the KCC's domain key EC.Each SWT Other registration packets are received and decrypted using the common domain key DC.As a result, each SWT receives the other non-target domain key Oa
Extract X. If each SWT determines that the identity and version of the other KCC is a correct match, the security process occurs as described above. If the KCC [) and versions do not match, the secure call is terminated.

After the registration packet message is successfully decrypted, authentication message packets are exchanged between SWTs 1A and 7B. Processing for authentication packet messages is performed as described above for the common KCA case. Next, the random component message packet is sent to SW
Exchanged between T 1A and 7B. Again, this process is also performed for the common KCA as described above. Finally, the crypto sync message packet is sent to SWT 1A
and 7B and processed as described above.

When conducting a secure call between SWTs in different KCA areas but in a common KCCnR area, assuming a communication rate of 2400 baud, the time required to establish a secure call between the two SWTs is The time is approximately 15 seconds.

As shown in Figure 1, if a KCA is not providing service, the KCC that has authorized the relevant KCA will
can operate as a backup. User group backup is for user groups A, B and C
provided to any user group such as To do this, a backup tape of the out-of-service KCA is loaded into the KCC. To authorize users in such a configuration, the KCC acts as a KCA.

Initial authorization to KCA is done in the same way as initial authorization of KCA to SAD on SWT. For initial authorization to a KCA, a secure channel is created using a password and seed S edge for this particular KCA. For example, KCA A or regional authority A establishes a secure transmission path to central authority KCC. Once the secure transmission path is established, the KCA sends an authorization information packet. This packet contains the authority's identification signature (IDS), terminal serial number (TSN>
, EXa, DaX and SAD serial number 1ssN)
including.

The KCC uses registration packets to ensure that the KCA acts on its behalf when authorizing the user.
Respond to CA. Briefly, the KCC sends a lockout packet to the KCA, which is a list of unauthorized keys and the global decryption key [)C. Registration packets have newly generated asymmetric domain keys, which are encoded using the KCC's EC. This registration packet also contains the KCA's identification and access/clearance information.

When the authorization period for a particular KCA asymmetric domain key expires, the KCA reauthorizes a new key with the KCC. The re-authorization process is essentially similar to the initial authorization process, except that the global asymmetric domain key DC is not sent by the KCC unless the pre-configured authorization period has expired yet.

After authorization of a user by the KCA, the particular SWT that authorized this user generates a component covering the SAD, which is randomly generated and sends the SAD access area message encoded or covered by the component covering the SAD.
Stored in the WT's non-volatile memory. This SWT then stores the authentication packet, registration packet, TSN (terminal serial number) and SAD cover components. This S
WT also lists uncertified keys (LIKL),
and store the decoded vectors DC and Dxt covered by the same SAD cover section. On each use, the SAD cover components are updated.

FIG. 4 shows a block diagram of the KCC or KCA. Each KCA and KCC can be configured by a computer-controlled system.

This computer-controlled system includes a CPU, hard disk, backup tape device, printer, keyboard, display device, and communication interface terminal (NI
T>. This NIT is a special secure line terminal for interfacing to the KCC or KCA. This NIT has a modem connected to all of the user's modems in the case of a KCA and to the KCA in the case of a KCC.

The control console shown in FIG. 4 is composed of a display device, a keyboard, a CPU, a hard disk, and a backup tape device.

NIT is a communication between the user and KCA, or between KCA and KC.
Transfer data between C and C at high speed. The NIT also provides high speed communication directly between the user and the KCC, which acts as a KCA in backup mode.

Each NTT and SWT has a modem. These modems are capable of transmitting data at high speeds such as 2400 to 9600 baud, but are not limited to these speeds.

The keyboard inputs data to the CPU.

The display device outputs video from the CPLJ. The printer displays a video by hard copying the CPU output. The disk contains all operating information related to SWT.
Stores software and data paces, and in the case of KCC, information about the KCA. The backup tape device is sent to a KCC that is not in service.
Load information so that the KCC can perform the functions of a KCA. In general, the backup tape device will reload the system if the KCA or KCC is out of service.

While the preferred embodiment of the invention has been illustrated and described in detail, it is understood that various modifications may be made without departing from the spirit of the invention or the scope of the appended claims.
It is obvious that it is easy for a person skilled in the art.

[Brief explanation of drawings]

FIG. 1 is a block diagram illustrating a key distribution system implementing the principles of operation of the present invention. Figure 2 shows two
FIG. 2 is a block diagram for carrying out a secure call between two secure line terminals; FIG. 3 is a block diagram of a secure call between two secure line terminals provided by different authorization authorities but the same key authorization center. FIG. 4 is a block diagram of a key authorization center and a key authorization authority. KCC...Key Authorization Center, KCA...Key Authorization Authority, SWT...Secure Track Terminal, SAD...
...Security activation device, PSTN...Public switched telephone network F'lG. 3 F'lG.

Claims (1)

[Claims] 1. In a hierarchical key management system that allows some of a plurality of users to perform secure communication via a switched line network, the hierarchical key management system includes: a predetermined user group; each of said users previously authorized by a common authority; terminal means connected to said switched line network for performing secure communication via said switched line network; , each group corresponding to a group of users, the first terminal means communicating with the second terminal means via the switched line network; and the first and second terminal means comprising: A hierarchical key management system characterized in that secure communication is directly performed via the switched line network without being connected to the common authority. 2. said common authority is: a plurality of key authorization authority means for authorizing said users of a user group, said key authorization authority means corresponding to a user group and a terminal means group, each key authorization authority means said each of said plurality of key authorization authority means being connected to said terminal means of said corresponding group, said plurality of key authorization authority means being connected to said terminal means of said corresponding group; and key authorization center means connected to each of the plurality of key security authority means, wherein the authorization center means provides authorization authority to each of the key authorization authority means and provides access to different groups of terminals. 2. A hierarchical key management system as claimed in claim 1, further comprising said key authorization center means for permitting direct secure communications between means. 3. further comprising security operating device means corresponding to individual users and connectable to said terminal means, said security operating device means transmitting authentication, encoding and decoding information to said terminal means; 3. The hierarchical key management system of claim 2, wherein the hierarchical key management system is operative to store. 4. The hierarchy of claim 3, wherein the secure operating device means is further connected to the terminal means to enable the terminal means to program the secure operating device means with authorization information. type key management system. 5. The secure operating device means is further connected to the terminal means to enable the terminal means to repeatedly reprogram the secure operating device means with regenerated communication information. The hierarchical key management system according to claim 4. 6. The hierarchical key management according to claim 2, characterized in that the users of the user group are directly connected to the key authorization center means according to the conditions of the key authorization authentication means of the user group that is not in service. system. 7. A method for secure communication via a telephone network between at least two terminals, each said terminal receiving prior authorization from a common authority, said method comprising: transferring information between said two terminals; exchanging encoding keys between the two terminals under the encoding key of the common authority; transmitting each transfer and key pair to the terminals; determining a second modified encoding/decoding key pair unique to each terminal for subsequent secure communications; A method characterized in that it consists of a storing step. 8. The method of claim 7, further comprising the step of: inserting a secure operating device into the terminal to permit each user of the corresponding terminal to engage in secure communications. 9. The method further comprises the step of verifying information contained in the secure operation device by the terminal to ensure that the user is currently authorized.
Method described. 10. In a hierarchical key management system that allows a plurality of users to conduct secure communications via a telephone network, the hierarchical key management system includes: a predetermined user group of the users; each group is a user group; a group of terminal means corresponding to said group of terminal means, each of said terminal means being capable of carrying out secure communication with other users up to a predetermined number of users via said telephone line network; group; and permitting said users of a user group to use said terminal means for conducting secure communications with other users of said user group;
A hierarchical key management system comprising key authorization means for allowing secure communication between groups of groups.