JPH0522282A - Communication data ciphering system between end systems - Google Patents

Abstract

PURPOSE:To ensure the security of the entire network system by applying ciphering processing to a user data only. CONSTITUTION:A data received from a section layer (S layer) consists of an S layer header and an S layer user data. A transport layer (T layer) ciphering sub-layer 8 ciphers the data as a T layer user data 11 of a transport protocol data unit (TPDU) and adds a ciphering header 19 and a T layer header 18 to the data 11 and gives the result to a subordinate layer. A T layer ciphering sub-layer 8 of an opposite end system decodes the user data 11 of the received TPDU fro the subordinate layer 12 and gives the result to an S layer 9 being a host layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication data encryption method between end systems which performs encryption processing to protect user data of communication data having a layer structure.

[0002]

2. Description of the Related Art Conventionally, in order to cryptographically process the data of an application program, (a) encryption / decryption is performed in the application program. In this case, the application program performs encryption processing and encryption key management, so that a highly confidential security method can be realized. However, on the other hand, the performance of the program is lowered, the price is increased, and the versatility is lost. In order to protect communication data when communicating between a computer system, a distributed system or a terminal system via a communication line or a network system, (b) communication is performed at the physical layer modem level. It was also possible to cryptographically process the data. However, in this case, since the encryption key is weak, there is a problem that it is not possible to cope with a more complicated network form. The above-mentioned two encryption methods, that is, the encryption in the application program and the encryption at the physical layer modem level, both have a problem that they can be used only by a fixed encryption method, and also have versatility. There wasn't. Therefore, in order to realize the cryptographic processing of the communication data of the application program in a more general and inexpensive manner,
(C) We are studying the corresponding methods in the application layer and (d) transport layer. However, the application
When performing encryption processing at the application layer level, it is necessary to develop encryption processing for each support product. Therefore, it is judged that it is more appropriate to deal with it in the transport layer.

[0003]

On the other hand, although a security system for each layer is currently under study in OSI, there are the following problems in the concept of transport layer security. That is, in the security protocol of the transport layer, TPDU (Transpo
rt Protocol Data Unit (Transport layer data)
(The entire data) is encrypted, and then SET is used as an encryption header.
It is supposed that RDU (Security Encyclopedia TRDU) (inclusion type TPDU) is added and transmitted.
However, in a conventional network system composed of LAN and WAN, a gateway (GW) for absorbing the difference in network system form is required. In this case, the TPDU It also becomes necessary to refer to the header part. When referring to the header part of the TPDU in the gateway (GW), according to the security model of the transport layer, the data encrypted by the relay node must be decrypted once. Therefore, it is necessary to manage the encryption key in the relay node.
However, there is a problem that the security function of the entire system is deteriorated and the overhead is increased. In considering the security of the system, in addition to confidentiality and integrity by cryptographic processing, access control that does not allow unauthorized access, business authentication, and security audit are necessary. Note that, as a document relating to the encryption of communication data in the related art, for example, "T layer security model (IS
O / IEC JTC1 / SC6 N4T31) "AK
ey Management Algorithm for Secure Commun
ication in Open Systems Interconnection A
rchitecture Raju Ramaswamy (Computer & Sec
Urity, 9 (1990) 77-84). An object of the present invention is to solve such a conventional problem, to efficiently and economically secure the secrecy of the entire network system, and to realize the function of authenticating a communication partner between end systems. It is to provide a communication data encryption method.

[0004]

In order to achieve the above object, the communication data encryption method between end systems according to the present invention is (a) an authentication process for authenticating a communication partner system and a communication partner system. When it is determined that the result of the encryption key delivery process that delivers the encryption key necessary for the encryption process of communication data, the encryption key concealment process that keeps the delivered encryption key confidential, and the authentication process is appropriate, the system After the user data of the communication data having the inter-layer structure is encrypted, if the result of the encrypted data transmission process and the authentication process for transmitting to the communication partner system and the authentication process are judged to be appropriate, the communication partner Characterized by performing reception data decoding processing for decoding user data among communication data having a layer structure received from the system and data integrity confirmation processing for transmission / reception between communication partner systems There is. In addition, (b) authentication processing, encryption key delivery processing,
The encryption key concealment process, the encryption data transmission process, the reception data decryption process, and the data integrity confirmation process are all characterized in that they are performed in connection units. Further, (c) the authentication process, the encryption key distribution process, the encryption key concealment process, the encryption data transmission process, the reception data decryption process, and the data integrity confirmation process are all computer systems and distributed system. , And when used in an application process between terminal systems, it is also characterized in that it is performed in connection units. Further, (d) in the case of performing encryption processing of business content data and management of encryption keys in the application process, processing for authenticating the connection used in the application process between the communication partner systems and communication partner The encrypted data transmission process that transmits the business content data of the upper application encrypted in the application process unit between systems to the communication partner system, and the application process unit received from the communication partner system. The encrypted data reception process that passes the encrypted work content data to the upper application as it is, and the data that confirms that the communication data in connection units transmitted and received between the communication partner systems has not been tampered with. Data integrity confirmation processing,
It is also characterized in that it can be used by an application program interface.

[0005]

In the present invention, a communication data encryption system is realized in which only the user data of communication data having a layer structure is subjected to encryption processing. This enables encryption processing for each connection between end systems and between end systems. In particular, since only the user data of the communication data is encrypted, the decryption process in the relay node of the network system composed of LAN and WAN becomes unnecessary, and the communication of the network system is performed. Data confidentiality,
High performance can be secured. In addition to the fact that user data encryption processing can be used from the upper application,
When the business application data is encrypted by the upper application, the user data can be passed to the communication partner system as it is. Therefore, based on the idea of realizing a security function as a system total, the functions of confidentiality, integrity, and communication partner authentication of communication data between end systems can be realized in general.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The principle and embodiments of the present invention will be described in detail below with reference to the drawings. First, the principle of the present invention will be described. In order to solve the conventional problems, the present invention requires an extension for applying the transport layer security protocol to the current network. In the transport layer security protocol under consideration in the OSI standard, the entire TPDU (entire transport layer data) is encrypted. However, as described above, in the conventional network system composed of LAN and WAN, it is necessary to refer to the header part of the TPDU in the relay node, so the encryption process must be once decrypted by the GW or the like. Will not happen. If the decryption is performed by the relay node, it is necessary to manage the encryption key in the relay node, resulting in deterioration of the security function and performance deterioration of the entire network system. Therefore, in the present invention,
It is necessary to extend the protocol so that only the user data of the communication data (for example, TPDU) having the layer structure is encrypted. Since only the user data is the target of the cryptographic processing, the modification by the cryptographic processing can be limited to only the entity in the transport layer. Therefore,
It is possible to reduce the influence on the existing processing without changing the service primitives between the upper layer and the upper layer, and the decoding processing by the GW becomes unnecessary. Further, if the application program can directly use the above functions, business level security becomes possible and fine-grained security can be realized. for that purpose,
In addition to making the above encryption processing available from the upper application, it is necessary to provide an application program interface that can be applied even when the business content data is encrypted by the upper application. . By specifying this application program interface, the communication data protocol for the user data encryption processing and the communication data protocol other than the encryption processing can be used from the upper application. It will be possible.

FIG. 1 is a system configuration diagram of data communication between end systems showing an embodiment of the present invention. In FIG. 1, a host system 1, a host system 2 and a workstation 3 are connected via a network system 24, and a workstation 4 is connected to the host system 2. There is. The host systems 1 and 2 have a communication management program 5 and an encryption key management program 6 built-in, and an encryption device 7 directly connected to the channel is connected. An operating system 25 is interposed between the host systems 1 and 2 and the channel direct connection encryption device 7. Although not shown here, the workstations 3 and 4 also have a program module having a function corresponding to the communication management program 5, the encryption key management program 6 and the channel direct connection encryption device 7 installed. Has been In addition, the host system 1,
In FIG. 2, an upper application program 23 operated by the user is loaded. The definitions and roles of the communication management program 5, the encryption key management program 6, and the channel direct connection encryption device 7 are as described below. (A) Communication management program 5 ... A program that implements a communication data encryption method between the end systems 1 and 2, (b) Cryptographic key management program 6 ... Program to manage,
(C) Channel direct connection encryption device 7 ... Master key management,
And RSA (Rivest-Shamir-Adleman scheme ci
pher), DES (Data Encryption Standard), and other devices equipped with a program for performing data encryption / decryption by an algorithm.

FIG. 2 shows a user key management table according to the present invention.
It is a figure which shows the example of a bull. As shown in FIG. 2, the user key management table 16 is stored in the key management program 6 in the host systems 1 and 2. The key includes a master key, a user key, and a data key, and both have a public key and a secret key. The master key is built in the channel direct-coupling encryption device 7, and based on this, a user key for the end system is created. The data key is necessary to encrypt communication data when establishing a connection, and is transmitted and received between communicating systems. The user key is used to protect the data key. To be This user key is a pair of a public key and a secret key, and each end system uses the user key management table 16 in its own system for the pair of the public key and the secret key and the communication partner system. Must have a public key.
That is, as shown in FIG.
In the key management table 16, the public key P1 and secret key S1 of the host system 1 which is the self system and the public key P2 of the host system 2 which is the partner system are registered, and the other host system 2 User key management table 1
6 is the public key P of the host system 2 which is its own system.
2 and the secret key S1, and the public key P1 of the host system 1 which is the partner system are registered. As key management methods, there are a key sharing method within a group, a key sharing method between peer groups, and a hierarchical group key sharing method.
Only the public key is stored by the peer-to-peer group sharing method.

(1) First, cryptographic processing between end systems will be described. FIG. 3 shows O of the T layer encryption sublayer.
The figure showing the positioning in the SI basic reference model, FIG.
FIG. 5 is a diagram showing the relationship between the data received from the layer and the user data of the TPDU, FIG. 5 is an operation flowchart of the connection establishment function, and FIG. 6 is an operation flowchart of the encrypted data transfer function. A chart and FIG. 7 are operation flowcharts of the connection release function. Communication data between end systems
A case where only the user data of the TPDU of the data is encrypted will be described. In layering by OSI, from bottom to top,
Physical layer (P layer), data link layer (D layer), network
It is divided into seven layers: a layer (N layer), a transport layer (T layer), a session layer (S layer), a presentation layer (PR layer), and an application layer (A layer). The physical layer to the transport layer is called the lower layer, and the session layer to the application layer is called the upper layer. FIG. 3 shows the position of the T-layer cryptographic sublayer 8 in the OSI basic reference model, which performs the cryptographic processing of the TPDU user data. The T layer encryption sublayer 8 encrypts the data 10 received from the S layer 9,
This is created as TPDU user data 11 and passed to the other end system. The T-layer encryption sublayer 8 of the other end system receives the TPD received from the lower layer 12.
The user data 11 (object of encryption) of U is decrypted and passed to the S layer 9 which is an upper layer. FIG. 4 shows the relationship between the data 10 received from the S layer and the TPDU user data 11. That is, the data 1 received from the S layer
0 consists of an S layer header and S layer user data. The T-layer encryption sub-layer 8 encrypts the data and the T-layer user data 1
It is created as 1, and the encrypted header 19 and the T layer header 18 are added and passed to the lower layer. The user of the TPDU of the present invention
The encryption processing of only the (a) connection establishment function,
It realizes three functions: (b) encrypted data transfer function and (c) connection release function. Above (a) (b) (c)
Will be described in detail with reference to FIGS. 5, 6 and 7, respectively. In the flow of the connection establishment function of FIG. 5, it is necessary to negotiate the following items defined by the security model of the T layer before communication. Negotiation items (function selection) key level, confidentiality, integrity (encryption key) security label, final sequence number,
Initiator designation of cryptographic association, remote identification, opposite address

In FIG. 5, the communication management program 5 of the host system 1 loads the user key management table 16 from the encryption key management program 6 prior to communication (step 51). Next, the communication management program 5 passes the random number and the public key P2 to the channel direct-coupling encryption device 7 and sends them to the data
Ask the user to create the key 15 (step 52). As a result, the encryption device 7 encrypts the data key 15 with the public key P2 and passes the key information 17 to the communication management program 5 (step 53). Next, the communication management program 5
The key information 17 is attached to the connection establishment request and transmitted to the host system 2 (step 54). On the other hand, the communication management program 5 of the host system 2 loads the user key reason table 16 from the encryption key management program 6 prior to communication (step 56). And after waiting,
Upon receiving the connection establishment request, the communication management program 5 passes the key information 17 and the secret key S2 to the channel direct-coupling encryption device 7 (step 57). Thereby, the encryption device 7
Decrypts the data key 15 from the key information 17 and saves it for subsequent encryption of communication data (step 5).
8). Next, the communication management program 5 sends a connection establishment response to the host system 1 (step 5).
9). As a result, the connection is established (step 55). The encryption key delivery means for delivering the encryption key is
Steps 51 and 56 are in charge, and step 58 is in charge of processing by the encryption key concealing means.

In the encrypted data transfer function shown in FIG.
The processes 1 to 64 are processes by the encrypted data transmitting means, and the processes 65 to 68 are processes by the receiving data decoding means. First, the communication management program 5 transfers the data 10 received from the S layer to the encryption device 7 (step 6).
2). As a result, the encryption device 7 DES-encrypts the data 10 with the data key 15 and performs the TPDU user data 1
1 is created and passed to the communication management program 5 (step 6
3). Next, the communication management program 5 adds the T-layer header 18 and the encryption header 19 to the TPDU user data 11 and sends it to the communication partner system (step 64). When there is reception data, the communication management program 5 of the partner system receives the user data of the TPDU received from the lower layer 12.
Data 11 to the encryption device 7 (step 66). As a result, the encryption device 7 outputs the TPDU user data 11 to the data.
The data is decrypted by the data key 15 and the data 10 is obtained and passed to the communication management program 5 (step 67). Next, the communication management program 5 processes the data 10 (step 6).
8).

The connection release function shown in FIG. 7 is used when the encrypted communication processing ends and when a failure occurs. Failures include cases where security has been breached. Specifically, depending on who is identified by the authentication means as the communication partner, or by the data integrity confirmation means. This is the case when the data has been tampered with. First, the communication management program 5 of the host system 1 sends a connection disconnection request to the host system 2 (step 71). Communication management program 5 of host system 2
Receives a connection disconnection request from the host system 1 (step 72). The communication program 5 of the host system 2 uses the data key 15 used in this connection.
Is deleted (step 73). Next, the communication management program 5 disconnects the connection to the host system 1 (step 74). This disconnects the connection (step 75).

FIG. 8 is a flowchart of a process for authenticating a communication partner when the connection is established in FIG.
First, the communication management program 5 of the host system 1 adds the authentication information 20 to the connection establishment request and transmits it (step 81). The communication management program 5 of the host system 2 determines whether the communication partner is valid according to the authentication algorithm pre-negotiated (step 83). If the communication partner is not valid (step 8)
4) Reject the connection establishment request (step 8)
5). If it is legitimate, a connection establishment response is returned (step 86). This disconnects the connection (step 82). FIG. 9 is a CR TPDU and CCT used when establishing a connection in FIG.
It is a figure which shows the structural example of PDU. The CR (Connection Request) TPDU is L1, '1 as shown in FIG.
110'CDT, DST-REF, SRC-REF, class and option, variable part, and user data. Furthermore, the variable part is the security parameter
(11000101), parameter length, and parameter value (key information 17, authentication information 20). CC
The (confirm) TPDU is also CR, as shown in FIG.
It has the same structure as the TPDU format.

FIG. 10 is a flow chart of data integrity confirmation processing for confirming that the communication data has not been tampered with during the transfer of the encrypted data in FIG. The host system 1 uses the data 10 received from the S layer as an input value to create a MAC in accordance with the integrity algorithm pre-negotiated, adds the MAC to the data in process 64, and transmits the data ( Step 111). The host system 2 compares the decrypted value from the MAC with the decrypted value of the data created in the process 64 according to the integrity algorithm previously negotiated (step 112). ). If they match (step 113), the data has not been tampered with and the process continues (step 114). Also, if they do not match,
Create and send an error message (step 11)
5). 11 and 12 are DT (data) TPDU and ED (wired data) used for the encrypted data transfer of FIG.
FIG. 7 is a data format diagram of TPDU. DT T
As shown in FIG. 11, the PDU is L1, CC (110
1), CDT, DST-REF, SRC-REF, class and option, variable part, and user data. Further, the variable part is composed of a security parameter code (11000101), a parameter length, and a parameter value (data length 21 before encryption, MAC information 22). The ED TPDU is L1, ED (00010000), DST-R, as shown in FIG.
It is composed of EF, ED-RODU-NR, EOT, variable part, and user data. In addition, the variable part has a security parameter code (1100010).
1), parameter length, parameter value (data length before encryption 2
1, MAC information 22). Figure 13
DR TP used when releasing the connection shown in FIG.
It is a format structural drawing of DU. DR TPDU is
As shown in FIG. 13, L1, DR (1000000
0), DST-REF, SCR-REF, reason, variable part, and user data. In addition, the variable part has a security parameter code (1100010).
1), parameter length, parameter value (data length before encryption 2
1, MAC information 22).

(2) Next, the case where the encryption process is performed in connection units will be described. FIG. 14 is a diagram showing an example of the data key management table. An embodiment in which only the user data of the TPDU of the communication data is encrypted for each connection between the end systems will be described. This is the same as the above embodiment (1) in that the TPD user data encryption process is performed by the T layer encryption sublayer 8, but the data key 15 is managed in order to perform the encryption process in connection units. It needs to be done for each connection. FIG. 14 shows an example of the data key management table for each connection. a1, a
2, ... are connection numbers, and the respective data keys (xx) (ΔΔx) (○ * ×) (ΔΔx)
... is registered. It is also possible to use different data keys 15 bidirectionally between the communication systems. In that case, different key information is designated by the key information 17 of DR TPDU and the key information 17 of CC TPDU in FIG. To do.

(3) Next, the cryptographic processing of the upper application will be described. FIG. 15 is a diagram showing an example of an application program interface. The encryption processing by the upper application program 23 may be such that the upper application uses the encryption processing of the user data, or there is the case where the upper application performs the encryption processing of the business content data. . In both cases, the data can be specified by specifying it with a common application program interface.
Data confidentiality, integrity, and authentication of the other party.
When the upper application uses the cryptographic processing of the user data, the application process may cryptographically process the user data of the upper application 23 for each connection between end systems. In this case, the encryption process of the user data of the upper application 23 is performed by T
The point that the layer encryption sublayer 8 is performed is the same as that of the above-mentioned embodiment (1), and the point that the data key 15 is managed in connection unit in order to perform the encryption process in connection unit is the same as the above-mentioned embodiment (1). Same as 2). Further, as in the embodiment (2), it is possible to use different data keys 15 bidirectionally between the communication systems. In addition, the upper application
When the application 23 performs the confidentiality and integrity of the above user data and the authentication of the communication partner, the application program interface shown in FIG. 15 is used. A communication partner authentication request 120, a data encryption request 121, a data decryption request 122, and a data integrity confirmation request 123 are used as this application program interface.

When the business application data is encrypted by the upper application, the user data may be passed to the communication partner system as it is because the user application is encrypted by the upper application. . It is possible to perform the cryptographic processing by the upper application and also perform the cryptographic processing by the T-layer cryptographic sublayer 8. However, in consideration of economical efficiency and performance, the cryptographic processing is performed by the T-layer cryptographic sublayer 8 in this embodiment. An example of not performing will be described. By the authentication process shown in FIG.
The connection used by the upper application association can be authenticated. If it is desired to perform further authentication for business operations, the higher-level application can independently perform the authentication. Further, the encryption key can be delivered by the encryption key delivery process shown in FIG. However, the delivery function of this encryption key can be performed independently by the upper application. By the cipher data transmission process shown in FIG. 6, the business content data of the upper application encrypted in association units is transmitted to the communication partner system. Since the business content data of this upper application is encrypted, it can be put in the field of the user data of the T layer as it is. On the end system side received by the encrypted data receiving process of the above data, the business contents encrypted in the unit of association entered in the field of the user data of the T layer are as they are. All you have to do is pass it to the upper application. In addition, upper application 2
3 uses the application program interface shown in FIG. 15, but does not use the application program interface of the data encryption request 121 and the data decryption request 122.

According to the present invention, since the communication data encryption method between the end systems which performs the encryption processing of only the user data of the communication data having the layer structure (a) can be realized,
The confidentiality of the entire network system can be maintained efficiently and economically. Especially, since only the user data of the communication data is encrypted, the decryption process at the relay node of the network system composed of LAN and WAN is unnecessary, resulting in confidentiality. In addition to this, it is advantageous in terms of operation and performance. (B) In addition to the encryption processing of communication data between end systems, the encryption processing for each connection between end systems and the upper application
It can also be applied to cryptographic processing in applications. Furthermore, when the business application data is encrypted by the higher-level application, the user data can be passed to the communication partner system as it is, so that it can be used as a system total in a wide variety of system configurations. A security function can be realized.

[0019]

As described above, according to the present invention,
Since only the user data is encrypted, the confidentiality of the entire network system can be secured efficiently and economically.
Therefore, it is extremely useful for protecting communication data between a computer system, a distributed machine system, or a terminal system, which is connected through a communication line or a network system and which implements a network function having a layer structure. It is valid. In addition, since the relay node of the network system such as LAN does not require the decoding process, the performance is improved,
And it is also advantageous in operation.

[0020]

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an inter-end system communication system showing an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a user key management table in FIG.

FIG. 3 is a diagram showing the positioning of a T-layer encryption sublayer in the OSI basic reference model according to the present invention.

FIG. 4 is a diagram showing the relationship between the data received from the S layer and the user data of the TPDU.

FIG. 5 is an operation flowchart of the connection establishment function in the present invention.

FIG. 6 is an operation flow chart of the encrypted data transfer function in the present invention.

FIG. 7 is an operation flowchart of the connection release function in the present invention.

FIG. 8 is an operation flow chart of an authentication function of communication data in the present invention.

FIG. 9: CR TPDU and CC TPDU forwarding
It is a mat block diagram.

FIG. 10 is an operational flowchart of a function for confirming the integrity of communication data in the present invention.

FIG. 11 is a format configuration diagram of a DT TPDU.

FIG. 12 is a format diagram of ED TPDU.

FIG. 13 is a format diagram of a DR TPDU.

FIG. 14 is a diagram showing an example of a data key management table in the present invention.

FIG. 15 is a diagram showing an example of an application program interface according to the present invention.

[Explanation of symbols]

1, 2 host system 5 Communication management program 6 Key management program 7-channel direct encryption device 23 Upper application program 24 Network system 25 operating system 16 user key management table 8 T layer encryption sublayer 12 Lower layer 11 T layer user data 18 T layer header 19 encrypted header 17 Key information 20 authentication information 21 Data length before encryption 22 MAC information

Claims (4)

[Claims] 1. A communication data encryption method between a computer system, a distributed machine system, and a terminal system, which are connected via a communication line or a network system and implement a network function having a layer structure, Authentication processing for authenticating the communication partner system, encryption key distribution processing for distributing an encryption key necessary for encryption processing of communication data between the communication partner systems, and encryption for concealing the distributed encryption key. When it is determined that the results of the key concealment process and the authentication process are appropriate, the user data of the communication data having the layer structure between the systems is encrypted, and then the encrypted data transmitted to the communication partner system. -Decoding the user data among the communication data having the layer structure received from the communication partner system, when the results of the data transmission process and the authentication process are judged to be appropriate. A communication data encryption method between end systems, characterized by performing a received data decryption process and a data integrity confirmation process transmitted and received between the communication partner systems. 2. The communication data encryption method between end systems according to claim 1, wherein said authentication processing, encryption key distribution processing, encryption key concealment processing, encryption data transmission processing, reception data.
The data decryption process and the data integrity confirmation process are both performed on a connection-by-connection basis. 3. The communication data encryption method between end systems according to claim 1 or 2, wherein the authentication processing, encryption key distribution processing, encryption key concealment processing, encryption data transmission processing,
Both the reception data decoding process and the data integrity confirmation process are characterized in that they are performed for each connection when they are used in the application process between the computer system, the distributed system and the terminal system. Communication data encryption method between end systems. 4. An application process between a computer system, a distributed machine system, and a terminal system, which are connected via a communication line or a network system and implement a network function having a layer structure. -When performing encryption processing of business content data and management of encryption keys in the application process, processing for authenticating the connection used in the application process between the communication partner systems and the application between the communication partner systems Encrypted data transmission processing for transmitting the business content data of the higher-level application, which has been encrypted for each application process, to the communication partner system, and for each application process received from the communication partner system, encrypted. Receives encrypted data that passes the business content data directly to the higher-level application The processing and the data integrity confirmation processing for confirming that the communication data for each connection transmitted and received between the communication partner systems have not been tampered with are utilized by the application program interface. Communication data encryption method for each connection between end systems.