JPH10327193A - Encipherment system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable cipher communication immune in security by deciphering data according to analytic information reported from an enciphered verification processing means, dispatching the deciphered information to a transmitting means and enciphering the received information by analyzing the condition of enciphering from a count value reported from a counter. SOLUTION: A packet analytic means 40 performs analysis from the header information of received packet data and determines the dispatch of these packet data to a transmitting means 20 with enciphering, deciphering or no processing. When the data are analyzed as a high-order protocol to be enciphered, these packet data are enciphered by an enciphering/deciphering means 80 on the conditions corresponding to the value reported from a counter 70, and an SPI value corresponding to the condition of enciphering is reported to an SPI processing means 60. The enciphered packet data are sent out after a security verification header is generated/added by an AH processing means 50 and the SPI processing means 60.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an encryption system such as a gateway device used for connecting an intranet to the Internet and the like, and more particularly, to an encryption system between terminals of a specific group such as offices distributed over a wide area. The present invention relates to an encryption method in a packet communication system in which arbitrary plural terminals recognize a common encryption algorithm and an encryption parameter when performing communication.

[0002]

2. Description of the Related Art When data is transmitted via the Internet or the like, an encryption communication system is used to keep data confidential.

FIG. 6 is a diagram showing a conventional cryptographic communication system. Terminal 720 _1, 720 _2, ..., 720 encryption gateway device 700 to the terminal of the A group of _n is external, terminal 730 _1, 730 _2, ..., encryption gateway device 710 to B group of terminals made of 730 _n Externally attached. The cryptographic gateways 700 and 710 are interconnected via a network 740. Terminal 720 _1, 720 ₂ of the A group, ..., 720 terminal 730 _n and B group _1, 730 _2, ..., in the communication between the 730 _n, the packet data communicated via the encryption gateway 700 and 710 Parameters such as an encryption algorithm and a key used for encryption are set in the encryption gateway 700,
It is fixed between 710. Originally, in such a cryptographic communication system, two cryptographic gateways 700, 71
Packets that do not pass through 0 should not be decrypted, but in the network 740 on the way, these encrypted packets are intercepted, the encryption algorithm and key of the packets are decrypted, and important information is intercepted. In addition, JP-A-7-107082 discloses that
There is disclosed a cryptographic gateway device that can select encryption / non-encryption and session key selection for each combination of terminals or each session.

Further, RFC (request for comments) 1
825-1828 describes "Security Architec" which deals with security in IP (Internet Protocol).
7 (hereinafter referred to as IPSEC). FIG. 7 shows the IP protocol defined by the IPSEC.
It is a figure explaining the security authentication header for P (AH). The security authentication header (AH) includes a header identifier after this header, the length of this header, and SPI (Secu).
rity Parameter Index) and variable-length authentication data. Then, in each IP packet, it is inserted between the IP header and the IP datagram.

[0005] This security authentication header is used to improve the confidentiality of IP packet data by using it.
Since it is intended for use in N (Virtual Private Network), the SPI (Security paramet) stored in the security authentication header
er index) is the US IANA (Internet Assigned Nu
mber). If the security function based on this header is applied to an intranet in a company, it will hinder data traffic that does not require management or security in the intranet of the SPI.

[0006]

The above-mentioned conventional encryption method has a problem that an encryption algorithm between encryption gateways and a key to be used are fixed. No matter how strong the encryption algorithm is, there is a problem in security that encryption is always performed by the same algorithm.

Further, in a conventional cryptographic gateway, RF
There is a problem that it is difficult to support the security technology of the IP packet specified by C1825-1828 (IPSEC) for the intranet. IPSE
The SPI specified in C is unique to the global network and, as described above,
This is because ANA manages this SPI on a global scale, and it is not practical to allocate such SPIs to individual intranets.

[0008] An object of the present invention is to solve the problem of a fixed encryption algorithm used by a conventional cryptographic gateway.
In the packet data sent to the external network,
Selects a service that requires encryption, uses the SPI of the security authentication header in IPSEC for each packet data to be sent, changes the encryption for each data packet, and performs encryption based on the information in the SPI. It is to provide a method. In particular, in an inter-office network (intranet), an SPI is generated and analyzed between cryptographic gateways, and a global network such as the Internet is provided with an encryption method for performing encryption using an IANA-specified SPI. It is in.

[0009]

SUMMARY OF THE INVENTION The encryption method of the present invention comprises:
In an encryption method in a gateway for connection to a network, a transmission unit for assembling and transmitting transmission information to be transmitted to and from the network in which the gateway is arranged, and a reception unit for receiving reception information transmitted from inside and outside the network. Analyzing the header information of the received information received by the receiving means, encrypting the received information,
A packet analyzing means for performing one of a decryption process and a non-processing process to determine whether the received information is transmitted from the transmitting means; and analyzing the encrypted authentication information in the header information and encrypting the encrypted received information. Authentication processing means for generating and providing encrypted authentication information, a counter for counting the number of information to be encrypted, and decrypting the data in accordance with the analysis information notified from the encrypted authentication processing means to the transmitting means The received reception information is passed, the encryption mode is analyzed from the counter value notified by the counter, the reception information is encrypted, and the encrypted reception information is passed to the encryption authentication processing means. Encryption / decryption means for notifying encryption / authentication information to be added to the information to the encryption / authentication processing means, and the packet analysis means determines that neither encryption nor decryption is required. Received information is characterized in that passed to the transmission means as a still transmitting information untreated.

[0010] Here, the encryption mode is also called an encryption pattern, and is a general term for an actual encryption procedure and parameters. Specifically, an encryption algorithm and a key used for encryption are used. Such patterns are collectively indicated.

In the encryption system of the present invention, when a connection is made to a global network such as the Internet, it is preferable that the encryption / decryption means executes processing according to the IPSEC specification.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a preferred embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an encryption gateway which is an encryption system according to an embodiment of the present invention. Here, it is assumed that the security authentication header (AH) described above with reference to FIG. 7 is used as the encrypted authentication information.

The encryption gateway 10 includes: (1) a transmission unit 2 for assembling and transmitting packet data to be transmitted to and from the network in which the encryption gateway 10 is located.
0, (2) receiving means 30 for receiving packet data transmitted from inside or outside the network in which the encryption gateway 10 is arranged, and (3) encrypting or decrypting or not processing the packet data received by the receiving means 30 Packet analysis means 40 for analyzing from the header information of the received packet data whether or not to pass the data to the transmission means 20; (4) header information included in the security authentication header (AH) of the data requiring decryption; AH processing means 50 for analyzing the data and generating and adding a security authentication header to the encrypted data, (5) SPI for generating and adding an SPI to the security authentication header of the data requiring decryption The processing means 60, (6) counts the number of packet data determined to require encryption by the packet analysis means 40. The decoding mode is analyzed based on the SPI value notified from the SPI processing unit 60, and the data is decoded, the decoded data is passed to the transmitting unit 20, and The encryption mode is analyzed from the counter value notified from 70, the data is encrypted, the encrypted data is passed to the AH processing means 50, and the encrypted data is given to the SPI processing means 60. To notify the SPI value to perform
And decoding means 80. For the packet data determined by the packet analysis unit 40 that does not require encryption and decryption, the packet data received by the reception unit 30 is passed to the transmission unit 20 as it is. When connecting to a global network such as the Internet,
A process defined by PSEC (hereinafter, IPSEC process) is performed.

In this encryption gateway 10, AH
The processing means 50 and the SPI processing means 60 constitute an encryption authentication processing means.

Next, a network provided with the above-described encryption gateway will be described with reference to FIG. In the network configuration shown in FIG. 2, a cryptographic gateway 2 is installed in a unique intranet 400 operated by a company or the like.
00, 210, 220 are connected and the cryptographic gateway 220
Is a global network 50 such as the Internet
0 to the cryptographic gateway 230. Under the cryptographic gateway 200, terminals 300 ₁ and 300
_2, ..., 300 _n are connected to the subordinate in the encryption gateway 210, the terminal _{310 1, 310 2, ...,} 310 n are connected,
Under the control of the cryptographic gateway 230, the terminals 320 ₁ , 32
0 _2, ..., 320 _n are connected. Each of these cryptographic gateways 200, 210, 220, 230 is constituted by the above-mentioned cryptographic gateway 10.

Here, a communication session between the terminal 300 ₁ and the terminal 310 ₁ is defined as a communication session between the terminal 310 ₂ and the terminal 320 _1, and the terminal 300 _n and the terminal 300 ₂
And a communication session between. The communication session is a session via the network 400, the communication session is a session via the network 400 and the Internet 500, and the communication session is a session between terminals connected to a subnet under the cryptographic gateway 200. , The session does not leave the cryptographic gateway 200 to the external network. In the communication session, the inside of the Internet 500 is connected by VPN.

When performing encrypted communication on a session,
The packet data transmitted from the terminal 300 ₁ is received by the receiving means 30 shown in FIG. 1 in the cryptographic gateway 200 and analyzed by the packet analyzing means 40 as being a higher-level protocol to be encrypted, and the value of the counter 70 is incremented. Then, the encryption / decryption unit 80 performs encryption on the packet data in a mode corresponding to the value notified by the counter 70, and the encryption / decryption unit 80 converts the SPI value corresponding to the encryption mode into SPI Processing means 60
Notify. The AH processing unit 50 and the SPI processing unit 60 generate and attach a security authentication header to the encrypted packet data. The transmitting unit 20 performs a lower layer packet assembling process, and sends the packet to the intranet 400. Within the intranet 400, the packet data is routed and transferred to the encryption gateway 210 according to the destination address of the packet data.
This packet data is received by the receiving means 30 shown in FIG. 1 in the cryptographic gateway 210, analyzed by the packet analyzing means 40 as an upper protocol to be decrypted, and the information in the security authentication header is analyzed by the AH processing means 50. Then, the SPI processing means analyzes the SPI value given to the security authentication header. The analyzed SPI value is stored in the encryption / decryption unit 80.
Is notified, the encryption / decryption unit 80 performs the decoding of the mode corresponding to the SPI value to the packet data, the transmission unit 20, packet assembly processing in the lower layer is made and sent to the terminal 310 ₁ .

When performing encrypted communication on a session,
The packet data transmitted from the terminal 310 ₂ is received by the receiving unit 30 shown in FIG. 1 in the cryptographic gateway 210 and analyzed by the packet analyzing unit 40 as being a higher-level protocol to be encrypted, and the value of the counter 70 is incremented. The encryption / decryption means 80 performs encryption on the packet data in a manner corresponding to the value notified by the counter 70, and the encryption / decryption means 80 processes the SPI value corresponding to the encryption aspect by the SPI processing. Notify the means 60. The AH processing unit 50 and the SPI processing unit 60 generate and attach a security authentication header to the encrypted packet data. The transmitting unit 20 performs a lower layer packet assembling process, and transmits the packet to the intranet 400. Within the intranet 400, the packet data is routed and transferred to the encryption gateway 210 according to the destination address of the packet data.

This packet data is received by the receiving means 30 shown in FIG.
The packet analyzing means 40 analyzes the upper protocol to be decoded. At this time, the packet analyzing means 40 analyzes that the destination address does not belong to the intranet 400 and notifies the SPI processing means 60 of the fact. The SPI processing means 60 notifies the encryption / decryption means 80 of the necessity of the IPSEC processing, and
The decryption means 80 encrypts the packet data according to IPSEC. Then, the AH processing unit 50 and the SPI processing unit 60 generate and add a security authentication header to the encrypted packet data, and the transmitting unit 20 performs a lower layer packet assembling process, and transmits the packet to the global network 500.

In the global network 500,
The packet data is routed according to its destination address and transferred to the cryptographic gateway 230. The packet data transmitted to the cryptographic gateway 230 is received by the receiving unit 30 shown in FIG. 1 in the cryptographic gateway 230 and analyzed by the packet analyzing unit 40 as being a higher-level protocol to be decrypted. The packet analysis unit 40 notifies the SPI processing unit 60 of the upper protocol to be decrypted and the packet data received from the global network 500, and the SPI processing unit 60 sends a message to the encryption / decryption unit 80. On the other hand, it notifies that decoding is necessary according to ISPEC. Encryption / decryption means 80, performs decoding of packet data according to IPSEC, decoded packet data, packet assembly processing in the lower layer is made in the transmitting unit 20, it is sent to the terminal 320 _1.

In the session, the cryptographic gateway 20
Since no packet data is sent from 0 to another encryption gateway, no encryption is performed.
Transmission and reception of data is performed between the terminal 300 ₂ and 300 _n.

Next, details of the encryption / decryption processing in the encryption gateway of the present embodiment will be described. FIG. 3 is a flowchart showing an encryption / decryption process. FIG. 4 shows an IP (Internet Protocol) of packet data used in the present embodiment.
FIG. 5 is a diagram illustrating a header format, and FIG. 5 is a diagram illustrating a packet format according to the present embodiment.
As shown in FIG. 4, the configuration of the IP header is the same as that of a normal IP header, but in the present embodiment, the option field is used as a field for storing the security authentication header. Also, as shown in FIG. 5, the packet data after packet assembly in the lower layer has a MAC (media access control: Me) at the beginning.
dia Access Control), followed by an IP header, followed by an encryption area, and finally by a frame check sequence.

Returning to the flowchart of FIG. 3, the receiving means 30 first checks whether or not packet data has been received (step 101), and waits until packet data is received. Upon receiving the packet data, the receiving means 3
0 sends the packet data to the packet analysis means 40.

Upon receiving the packet data from the receiving means 30, the packet analyzing means 40 checks whether or not the packet is an IP packet, that is, checks the MAC header of the packet data to determine whether or not the upper layer protocol is IP (step 102). If the upper layer protocol is not IP, the process proceeds to step 114, and the packet data is
0 and transmitted. On the other hand, if the upper protocol is IP
In this case, the packet analysis unit 40 determines the higher-level protocol from the value of the protocol ("protocol") field in the IP header of the packet data,
It is determined whether the protocol is a higher-level protocol for decryption (step 103). If the protocol is a higher-level protocol that does not perform encryption / decryption, the process proceeds to step 114, and the packet data is passed to the transmission unit 20 and transmitted.

If it is determined in step 103 that the protocol is a higher-level protocol for performing encryption / decryption, the packet analysis unit 40 determines from the value of the IP header length (“IHL”) in the IP header of the packet data. Options ("optio
n ") field, and determines whether there is a security authentication header in the IP header (step 104). In the case of the present embodiment, the option field stores the security authentication header as described above. Therefore, the presence or absence of the security authentication header can be determined by the presence or absence of the option field.

If the security authentication header field is present in step 104, the packet is encrypted packet data, and the packet analysis means 40 determines the IP header length ("IHL") field and the IP header length in the IP header of the packet data. The IP header area and the IP datagram area are separated based on the value of the datagram length ("TL") field to obtain an IP datagram (step 105).
An IP header is obtained (Step 106). Further, the packet analysis unit 40 determines the source address (“Source Address”) and the destination address (“Destination”) from the IP header.
Address ") (step 107). Then, the packet analysis unit 40 determines from the acquired source address
It is determined whether the source address is outside the intranet (step 108). If the source address is outside the intranet, the packet analysis unit 40 notifies the SPI processing unit 60 of performing the IPSEC process (step 109), and proceeds to step 115 described later.

On the other hand, if the source address is within the intranet at step 108, the packet analysis means 40 passes the packet data to the AH processing means 50. As a result, the AH processing means 50 transmits the "length" in the security authentication header in the IP header of the packet data.
The variable length authentication data is obtained from the field (step 110), and the SPI processing means 60 obtains the SPI value from the "SPI" field in the security authentication header (step 111). Then, the encryption / decryption means 80
A decoding mode (decoding pattern) corresponding to the SPI value notified from the SPI processing unit 60 is selected, and the packet data is decoded according to the decoding mode (step 1).
12), proceed to step 113.

In step 104, if there is no security authentication header field in the IP header, it is determined that the packet data is plain text, and the process proceeds to step 115. In step 115, 1 is added to the value of the counter 70, that is, the value of the counter 70 is incremented. After the counter 70 is incremented, the packet analysis unit 40 determines whether the IP header length (“IHL”) field and the IP datagram length (“
TL ") field and the IP header area and IP
The datagram area is separated, an IP datagram is obtained (step 116), and an IP header is obtained (step 117). The packet analysis means 40, from the IP header,
Acquire the source address ("Source Address") and destination address ("Destination Address") (step 11)
8). Then, the packet analysis unit 40 determines from the acquired destination address whether the destination address is outside the intranet (step 119). If the source address is outside the intranet, the packet analysis unit 40 notifies the SPI processing unit 60 that IPSEC processing is to be performed (step 120), and step 113
Move to

On the other hand, if the destination address is within the intranet in step 119, the encryption / decryption means 80 determines the encryption mode (encryption pattern) corresponding to the counter value notified from the counter 70. Selected,
The packet data is encrypted according to the encryption mode (step 121). Then, the AH processing means 50 generates and adds a security authentication header to the packet data encrypted by the encryption / decryption means 80 (step 122), and the SPI processing means 60 executes the encryption / decryption means. The encryption mode selected by the encryption / decryption means 80 is notified from 80, and an SPI corresponding to the encryption mode is generated and added to the security authentication header (step 123), and the process proceeds to step 113. .

In step 113, the transmitting means 20 receives the packet data from any of the packet analyzing means 40, the AH processing means 50, and the encrypting / decrypting means 80, assembles the lower layer frame, and then performs step 114. Then, the packet data is transmitted to the terminal or another encryption gateway according to the transmission destination.

By performing the above processing, a series of operations associated with the reception of the packet data by the cryptographic gateway is completed.

[0032]

As described above, by implementing the encryption method according to the present invention on an existing gateway, when information such as packet data communicated between terminals is received, the source of the information, Depending on the destination, the communication service and the number of information to be encrypted, the information is transmitted with or without performing the encryption or decryption processing on the received packet data,
This has the effect of enabling encrypted communication with stronger security than existing encryption methods. Further, by selecting encryption / non-encryption for each communication service, it is possible to eliminate encryption work for information with low confidentiality and reduce the processing load.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a cryptographic gateway that is an encryption method according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of a network configuration including the cryptographic gateway illustrated in FIG. 1;

FIG. 3 is a flowchart showing an encryption / decryption process.

FIG. 4 is a diagram illustrating a format of an IP header of packet data.

FIG. 5 is a diagram illustrating a packet format in the present embodiment.

FIG. 6 is a block diagram showing a configuration of a conventional cryptographic communication system.

FIG. 7 is a diagram illustrating a configuration of a security authentication header.

[Explanation of symbols]

10,200,210,220,230 encryption gateway 20 transmission unit 30 reception unit 40 packet analyzing unit 50 AH processing unit 60 SPI processing unit 70 counter 80 encryption / decryption means 101 to 123 Step 300 ₁ ~300 _n, 310 ₁ ~ 310 _n , 320 ₁ ~ 320 _n
Terminal

Claims (2)

[Claims] 1. An encryption method in a gateway that connects to a network, wherein: a transmitting unit that assembles and transmits transmission information to be transmitted to and from a network in which the gateway is arranged; and a reception unit that transmits from and to the network. Receiving means for receiving information, analyzing the header information of the received information received by the receiving means, performing any one of encryption, decryption and no processing on the received information, Packet analysis means for determining whether to transmit from the transmission means; encryption authentication processing means for analyzing encrypted authentication information in the header information and generating and adding encrypted authentication information to the encrypted received information; A counter for counting the number of information to be encrypted, and decryption of data according to analysis information notified from the encryption / authentication processing means. To pass the decrypted reception information to the transmission means, analyze the mode of encryption from the counter value notified from the counter, encrypt the reception information, and encrypt the received information by the encryption authentication processing means. And encryption / decryption means for notifying the encryption / authentication processing means of the encryption / authentication information to be given to the encrypted reception information. The encryption method characterized in that the received information determined to require no decryption is passed to the transmitting means as transmission information without any processing. 2. The encryption method according to claim 1, wherein when connecting to a global network, said encryption / decryption means executes processing according to IPSEC specifications.