KR20030088643A - Method of encryption for gigabit ethernet passive optical network - Google Patents

Abstract

PURPOSE: A coding method in a gigabit ethernet-passive optical network is provided to improve the efficiency of encryption by including the exchange and manage of an encryption key into a scheduling procedure of the gigabit ethernet-passive optical network. CONSTITUTION: An optical line terminal(100) of an optical network unit(120) is registered(801,803,805). The optical line terminal(100) of optical network unit(120) is authenticated(807,809,811). The optical line terminal(100) generates a session key using an obtained public key of the optical network unit(120) in the authentication process, and the pseudo-random values. The optical line terminal(100) transmits the pseudo-random values to the optical network unit(120). The optical network unit(120), which receives the pseudo-random values, generates a session key using the received pseudo-random values and the public key of the optical line terminal(100).

Description

Encryption method in Gigabit Ethernet passive optical subscriber network {METHOD OF ENCRYPTION FOR GIGABIT ETHERNET PASSIVE OPTICAL NETWORK}

The present invention relates to a Gigabit Ethernet Passive Optical Network (EPON), which is a high-speed passive optical subscriber network, and more particularly, to an encryption method of a Gigabit Ethernet passive optical subscriber network.

The present invention relates in particular to an encryption method and encryption key information and thus overall scheduling flow in a Gigabit Ethernet passive optical subscriber network.

In general, the conversion of information into unknown information (cipher text) is called encryption. Encryption protects information by storing it in memory in the form of cipher text or by transmitting it on a communications line. When encryption is subdivided, it can be considered to divide into encryption and decryption normally. Encryption uses an encryption key (a specific bit sequence) to convert information into ciphertext, and decryption uses a decryption key to restore original information. Since only the person who has the decryption key can restore the correct information, the information can be protected if the decryption key is unknown to the third party. Cryptographic methods are largely divided into secret key cryptography (common key cryptography) and public key cryptography. The same key is used for both encryption and decryption of the secret key method. In the case of communication, the sender and the receiver need to keep the same key secret in advance. Public key cryptography, on the other hand, uses different keys for encryption and decryption. The encryption key is public and the decryption key is kept secret. In practice, there are many secret key cryptography methods, and DES (Data Encryption Standard) is a widely known method. On the other hand, in the following description, "encryption" and "decryption" are collectively referred to as "encryption" without distinguishing between "encryption" and "decryption" unless there is a special reason. That is, the term "encryption" to be used below is used as the term "encryption" and "decryption" collectively unless otherwise stated.

1 shows a configuration of a passive optical subscriber network device.

As shown in FIG. 1, the passive optical subscriber network includes one optical line terminal (OLT), and at least one optical network unit (ONU). 120).

The passive optical subscriber network shown in FIG. 1 may be further classified into an asynchronous transmission passive optical subscriber network and a gigabit Ethernet passive optical subscriber network. On the other hand, due to the development of Internet technology and the increased bandwidth demand at the subscriber side, it is relatively expensive and has a relatively low cost and high bandwidth than the asynchronous transmission technology that has a limited bandwidth and IP packet segmentation. There is a trend towards end-to-end transmission with gigabit Ethernet. Accordingly, in the passive optical subscriber network structure, the Ethernet method is required rather than the asynchronous transmission method.

Asynchronous Transmission Method The encryption scheme used by passive optical subscriber networks (ATM-PON, APON) is churning, and a 3-byte encryption key is used. This method has been used in APON because it has encryption capability that the encryption key value should be updated every second and it is a relatively simple algorithm, so it is possible to support high speed in APON with speed of 622Mbps. The encryption key value used in this method is created in the ONU 120 and provided to each OLT 100, and this value and the periodically updated encryption key values are put in the payload portion of the maintenance (OAM) cell. Delivered. In the case of APON, due to the limitation of encryption technology and the possibility of high speed support, 3 bytes of churning keys were used in the maintenance cell, but in this case, the capability of the encryption key itself is limited. In contrast, Gigabit Ethernet is relatively high speed compared to APON having a transmission rate of 622 Mbps. Therefore, it is technically inefficient to follow the encryption scheme of APON. It also has a point-to-multipoint structure that is relatively vulnerable to encryption. Therefore, in this case, the encryption problem of the user data of the uplink / downlink is important, it is necessary to select a strong and efficient encryption key scheme and effective operation. However, the encryption scheme and encryption key management scheduling scheme of Gigabit Ethernet passive optical subscriber network are currently being standardized in IEEE802.3ah. Accordingly, there is a need for an encryption method suitable for a gigabit Ethernet passive optical subscriber network.

An object of the present invention is to provide an encryption method in a gigabit Ethernet passive optical subscriber network.

Another object of the present invention is to provide a definition of an entire scheduling flow according to encryption key management and encryption key value exchange in encryption of a Gigabit Ethernet passive optical subscriber network.

The present invention to achieve the above object; In a Gigabit Ethernet passive optical subscriber network consisting of one optical fiber termination device and at least one optical subscriber network device, in an encryption method using an advanced encryption standard and a bidirectional scheme, registration of the optical fiber terminal device of the optical subscriber network device Process, authentication process for the optical fiber terminal device of the optical subscriber network device registered in the registration process, public key value and optical random number value generated by the optical fiber network device obtained in the authentication process Generating a session key by using a signal, transmitting a pseudo-random value to the optical subscriber network device by the optical fiber terminal device, and receiving a pseudo-random value by the optical subscriber network device during the authentication process A gigabit comprising the step of generating a session key using the public key value and the pseudo-random value of the end device. It proposes an encryption method of Ethernet FTTH.

1 is a diagram showing the structure of a passive optical subscriber network;

2 is a diagram illustrating an AES encryption application target;

3 is a diagram illustrating an information exchange interface including encryption key information around a MAC control sublayer;

4 illustrates a Mac control layer for cryptographic implementation;

FIG. 5 is a diagram in accordance with the present invention, illustrating cryptographic steps performed at the side of the optical fiber terminator; FIG.

6 is a diagram in accordance with the present invention, illustrating encryption steps performed in an optical subscriber device;

7 is a diagram illustrating an encryption key generation process for encryption in accordance with the present invention;

FIG. 8 is a diagram illustrating a signal flow between an optical fiber terminal device and an optical fiber terminal device including an encryption key value exchange according to an embodiment of the present invention;

9 is a diagram illustrating a signal flow between an optical fiber terminal device and an optical subscriber device according to another embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the reference numerals to the components of the drawings, it should be noted that the same reference numerals as much as possible even if displayed on different drawings.

As mentioned above, the term "encryption" used below is used to mean "encryption" and "decryption" unless otherwise stated. Accordingly, the "encryption key" used below is also used to mean "encryption key" and "decryption key."

The present invention relates, in particular, to encryption methods and encryption key information and thus the entire scheduling flow in a Gigabit Ethernet passive optical subscriber network. Special considerations when considering encryption in a Gigabit Ethernet passive optical subscriber network are users, namely ONU 120 authentication, encryption, and encryption key management. User authentication is performed after the ONU 120 registration period in the OLT (100) and each ONU 120 can not exchange data before user authentication. In addition, encrypting the uplink data and the downlink data is to prevent eavesdropping and to prevent impersonation of the unauthorized ONU 120. The encryption key is used for user authentication and encryption, and the encryption key management flow and scheduling of the encryption method differs depending on the operation and exchange method of the encryption key.

Meanwhile, the encryption method to be used in the Gigabit Ethernet passive optical subscriber network selected in the present invention is a symmetric method, AES (Advanced Encryption Standard), which is embodied by the Rijndael algorithm. AES is an encryption method that is superior to DES, and is a strong encryption method with an encryption key update period of 3 * 1017 years, especially for high-speed networks of more than gigabit. The AES method encrypts data in blocks, where the block size is 128 bits. The encryption key used in the AES method can be 128, 192 or 256 bits long.

In the present invention, a hybrid encryption method using both public and private keys is selected as the encryption type. This is to take advantage of the public key and private key only, the distribution key value uses the public key, the encryption method uses symmetric (symmetric). In the present invention, the OLT 100 and the ONU 120 generate a session key using two key values of the public key and the private key. That is, the public key exchanged between the OLT 100 and the ONU 120 is used for the purpose of generating a symmetric session key. As an authentication protocol, a two-way method of the X.509 standard was selected, which is used to exchange mutual certificates in the public key exchange between the OLT 100 and each ONU 120. In the present invention, a separate reference to the certificate and its parameters are omitted.

2 is a diagram showing a subject of encryption in the present invention.

In the present invention, in particular, the packet data unit (PDU) 202 is subject to encryption. K 201 in FIG. 2 is an encryption key value to be used in the encryption method proposed by the present invention, hereinafter referred to as a 'session key' value. That is, the "session key" in the present invention means an encryption key generated for use in the encryption method proposed by the present invention. In the present invention, the encryption key information to be exchanged between the ONU 120 and the OLT 100 is included in the Ethernet MAC control frame and transmitted to the lower layer. The process of including the encryption key information in the Ethernet MAC control frame is performed in the MAC control layer 210, and is performed in the AES function 204 of FIG. The AES function 204 includes the session key and the parameters for encryption in the PDU 202 to be encrypted and converts the encrypted PDU 206 into a PDU 206.

FIG. 3 is a diagram illustrating an inter-layer service interface showing information exchanged between an upper MAC control client sublayer and a lower MAC layer centered on a Gigabit Ethernet passive optical subscriber network MAC control layer where encryption occurs. In the figure, the encryption key value to be exchanged is expressed as "KEY". Referring to FIG. 3, information exchanged between the MAC control layer and the MAC layer becomes a destination address (DA), a source address (SA), a length / type, data, and an encryption key value (KEY). can see. Each step of the encryption will change the contents of this "KEY" field. First, when the ONU 120 transmits a user authentication request signal to the OLT 100, the public key value of the ONU 120 is set to OLT. When the OLT 100 transmits a user authentication response signal to the ONU 120, the OLT is set to OLT. The public key value of 100 is a pseudo-random number in the "KEY" field in the session key generation step.

4 is a diagram illustrating a Mac control layer for encryption implementation.

4 illustrates an SDE with other MAC control functionality such as ONU 120 registration (REG, Registration), ranging (RNG, Ranging), Dynamic Bandwidth Allocation (DBA), and the like. (Secure Data Exchange) is located in the Mac control sublayer 310. The upper layer 200 of FIG. 4 corresponds to three to seven layers among seven layers, and the Mac client sublayer 300, the MAC control sublayer 310, the MAC layer 220, and the like correspond to two layers. The physical layer 410 corresponds to one layer. The Mac client sublayer 300 performs functions such as LLC, bridge entity, and the like. In the present invention, encryption of the Gigabit Ethernet passive optical subscriber network is performed in the second layer. In particular, the layer including the MAC layer 220 and the MAC control layer 310 that performs functions such as REG, RNG, DBA, and SDE is referred to as a gigabit Ethernet passive optical subscriber network MAC layer 400.

5 illustrates a cryptographic finite state machine (FSM) in terms of OLT.

FIG. 5 illustrates only encryption-related flows, excluding the relationship with the flow of other control information between the ONU 120 and the OLT 100, and steps S0 500 to S7 514 are as follows. S0 500 is an initialization step, S1 502 is an authentication step, S2 504 is a public key acquisition step, S3 506 is a session key generation step, S4 508 is a session key sharing step, S5 510 Is an activation step, S6 512 is a new session key generation step, and S7 514 is a key exchange preparation step. Each step is described as follows.

First, in the SO 500 state, the OLT 100 performs initialization. When the initialization is made, the OLT 100 receives the authentication request signal (Authentication Request) sent from the ONU 120 (step 503) and proceeds to the authentication state of S1 (502). The authentication request signal includes a certificate. The certificate also includes a public key value of the ONU 120 transmitted by the X.509 protocol. In the authentication state 502, the OLT 100 determines the reliability of the ONU 120 and the like. If the reliability of the ONU 120 is recognized through the authentication request signal, the OLT 100 transmits an authentication response signal to the ONU 120 which has transmitted the authentication request signal (step 503). In step S2 (504), the public key acquisition step, the OLT 100 obtains the public key of the ONU (120). As a result, the OLT 100 knows its own public key, the public key of the ONU 120, and its own private key. The public key is included in the authentication request signal as described above. In order to transmit the actual data, the OLT 100 generates a session key using three key values and a pseudo random number of the public key, the public key, and the private key of the ONU 120. Since the session key has a symmetrical characteristic, the ONU 120 should also have the same key value. At this point, the OLT 100 transmits the pseudo random value to the ONU 120. Through this, the OLT 100 and the ONU 120 share a session key value. The OLT 100 receives a session key generation completion message from the ONU 120 (507). This completes the generation of the session key, and enters the session key sharing state of S4508. Meanwhile, after the session key value is generated, the OLT 100 and the ONU 120 encrypt the user data using the session key value and the AES encryption method until the key exchange time (S5 state) (510). After the process of generating the session key, the basic scheduling for encryption of the Gigabit Ethernet passive optical subscriber network is finished. Subsequent periods follow the operation of a typical passive optical subscriber network, which continues until a new session key is generated.

On the other hand, at the update time of the encryption key value, a countdown number for informing the update time from a few frames before the update of the encryption key value is included. In order to perform encryption key synchronization, when the encryption key exchange occurs after 5 frame periods, the number "5" is used. When the encryption key exchange occurs after 4 frame periods, the number "5" occurs Is inserted. When the key exchange time is reached (S6 state) 512, the OLT 100 terminates the current session and sends a pseudo-random value back to the ONU 120 to generate a new key. Meanwhile, an initialization request may occur in each of the states S1 502, S2 504, S3 506, S4 508, and S5 510 of FIG. 5, and when an initialization request occurs, an S0 500 state may occur. To transition to.

Figure 6 shows a cryptographic FSM on the ONU side.

If the initialization is made in the state S0 (600), the ONU 120 transmits an authentication request signal to the OLT 100 (step 601). The ONU 120 receives an authentication response signal from the OLT 100 (step 603) and obtains a public key of the OLT 100 included in the authentication response signal. The ONU 120 generates a session key by receiving a pseudo random value from the OLT 100 (step 605) (S3). As a result, the session key generation is completed, and the OLT 100 and the ONU 120 share a session key. The ONU 120 transmits a session key generation completion message to the OLT 100 (step 607). After the session key value is generated, the OLT 100 and the ONU 120 encrypt the user data using the session key value and the AES encryption method until the key exchange time. When the key exchange time comes, the ONU 120 generates a new key by terminating the current session and receiving a pseudo random value from the OLT 100 again.

7 is a timing diagram illustrating the steps of FIGS. 5 and 6.

7 illustrates a flow in which the OLT 100 and the ONU 120 generate a session key and transmit data in a state of knowing each other's public key and their private key. As shown in FIG. 7, the session key K is generated as a function having an input parameter of f (a, aP, bP, r) (704). In step 701, the OLT 100 is connected to the ONU 120. In order to generate the same session key, the pseudo-random value r is transmitted to the ONU 120. Upon receiving the pseudo random value, the ONU 120 generates a session key and transmits a session key generation completion message to the OLT 100 in step 706. In operation 705, the general grant signal including information on the position, size, and the like of the slot to transmit the OLT 100 data is transmitted to the ONU 120. The normal grant signal may include a slot position, a slot size, and the like in which each ONU 120 may request authentication so that authentication requests of the ONUs 120 do not collide with each other. This signal specifies. The type of grant signal at this time is set as an authentication grant and is set in a grant type field of a normal grant signal. In step 707, the ONU 120 transmits data to the OLT 100 according to the information included in the received normal grant signal.

8 is a diagram according to an embodiment of the present invention, showing the encryption procedure together with the general scheduling procedure of the GE-PON.

Steps 801 to 805 of FIG. 8 correspond to an ONU registration step. In step 801, the OLT 100 grants registration request signals to the ONUs 120 by transmitting registration grant signals to the ONUs 120. In operation 803, the ONUs 120 register the ONU 120 by transmitting a registration request signal at a time allocated to the ONU according to the information of the registration grant. In step 805, the OLT 100 transmits an authentication grant signal to the registered ONUs 120. Steps 807 to 811 are authentication and public key acquisition steps. In step 807, the OLT 100 transmits an authentication grant signal to the ONUs 120 that have been registered. Upon receiving the authentication grant signal, the registered ONUs 120 transmit an authentication request signal to the OLT 100 in step 809. In step 811, the OLT 100 transmits an authentication response signal to the ONUs 120 that are authenticated among the ONUs 120. Through the authentication request signal and the authentication response signal, the OLT 100 and the ONU 120 obtain their public key values, respectively. Steps 813 to 815 are session key generation steps. In step 813, the OLT 100 transmits the pseudo random value used to generate the session key to the ONU 120. Upon receiving the pseudo random value, the ONU 120 generates a session key and transmits a session key generation completion message to the OLT 120 in step 815. As a result, a procedure related to encryption is completed, and data is transmitted using the generated session key until a new session key generation request occurs. Since the steps below the step 817 correspond to a normal communication step, a description thereof will be omitted.

8 illustrates a process of authenticating a user after the ONU 120 registers with the OLT 100 and receives the ONU 120 ID from the OLT 100. In the above embodiment, there is an advantage that the loss due to the collision that occurs during registration is not affected.

In addition, as shown in Figure 9, after the user authentication, considering only the registered ONU 120 to register in the OLT 100 ID in the embodiment of Figure 8 without checking the user's reliability In addition, the overall scheduling procedure of FIG. 8 can be reduced.

This method can be registered only by the user whose authenticity is confirmed. That is, even if the ONU 120 which successfully registered the request without experiencing a collision cannot be authenticated, the ONU 120 ID is not assigned. This has the advantage that the overall scheduling procedure is reduced. The processes illustrated in FIG. 9 are described as follows. In step 901, the OLT 100 transmits a registration grant signal to the ONU 120. In step 903, the ONU 120 transmits a registration request signal and an authentication request signal to the OLT 100 together. When the registration process of the ONU 120 is finished in the OLT 100, the OLT 100 transmits an authentication grant signal for requesting authentication to the registered ONU 120. In step 905, the OLT 100 transmits a registration response signal and an authentication response signal to the ONU 120. As such, since registration and authentication are performed at one time, the OLT 100 does not need to transmit a separate authentication grant signal to the ONU 120. In step 907, the OLT 100 transmits the pseudo random number used to generate the session key to the ONU 120. Upon receiving the pseudo random value and generating a session key, the ONU 120 transmits a session key generation complete message to the OLT 100 in step 909. Since the steps below the step 911 correspond to a normal communication step, a description thereof will be omitted.

The present invention defines an appropriate encryption method in a Gigabit Ethernet passive optical subscriber network, and includes a method for exchanging and operating an encryption key value for operating the same in the scheduling procedure of the passive optical subscriber network. Efficient encryption procedure can be performed in Gigabit Ethernet passive optical subscriber network with multipoint structure.

Claims (7)

In a gigabit Ethernet passive optical subscriber network composed of one optical fiber termination device and at least one optical subscriber network device, an encryption method using an advanced encryption standard and a bidirectional scheme, Registration process of optical fiber termination device of optical subscriber network device; An authentication process for the optical fiber termination device of the optical subscriber network device that has been registered in the registration process; Generating, by the optical fiber terminal device, a session key using the public key value and the pseudo random number value generated in the optical subscriber network device obtained in the authentication process; Transmitting, by the optical fiber terminal device, the pseudo random value to the optical subscriber network device; Gigabit ethernet optical, wherein the optical subscriber network device having received the pseudo random number value generates a session key using the public key value and the pseudo random value of the optical fiber end device obtained in the authentication process. Encryption method of subscriber network. The method of claim 1, And transmitting, by the optical subscriber network device which generated the session key, a session key generation complete message to the optical fiber termination device. The method of claim 1, The authentication process may include transmitting an authentication request signal to the optical fiber terminator by the optical subscriber network device receiving the authentication grant signal from the optical fiber terminator; And transmitting an authentication response signal from the optical fiber termination device. The method of claim 3, And the authentication request signal and the authentication response signal include public key values of the optical subscriber network device and the optical fiber termination device, respectively. The method of claim 1, The session key generated by the optical fiber terminator is generated using the public key and secret key value of the optical fiber terminator, the public key value of the optical subscriber network device, and the pseudo random value generated by the optical fiber terminator. A method for encrypting a gigabit Ethernet optical subscriber network. The method of claim 1, The session key generated by the optical subscriber network device is generated by using the public and private key values of the optical subscriber network device, the public key value of the optical fiber termination device, and the pseudo random number value received from the optical fiber termination device. A method for encrypting a gigabit Ethernet optical subscriber network. In a gigabit Ethernet passive optical subscriber network composed of one optical fiber termination device and at least one optical subscriber network device, an encryption method using an advanced encryption standard and a bidirectional scheme, Receiving, by the optical subscriber network device, a registration grant signal from the optical fiber terminator; Transmitting a registration request signal to a fiber termination device; Receiving an authentication grant signal from the optical fiber termination device; Transmitting an authentication request signal to the optical fiber terminator according to the authentication grant signal and receiving an authentication response signal from the optical fiber terminator; Receiving a pseudo random value from the optical fiber terminator, generating a session key using the pseudo random value and the public key value of the optical fiber terminator included in the authentication response signal; And encrypting and transmitting user data using an advanced encryption method using the session key.