KR100809393B1 - Key distribution method on EPON - Google Patents

Abstract

The present invention is a key distribution method required for applying link security technology in EPON. The OLT and the ONU exchange the generated first random values, respectively, and perform a hash function based on the exchanged first random value and the pre-distributed master key to generate both master keys. In addition, the OLT and ONU mutually exchange the generated second random values, and perform a hash function based on the exchanged second random values, the MAC addresses of the OLT and the ONU, and the two master keys to form a unicast secure channel. Create a temporary key to use. In this way, the EPON can distribute keys securely without having a separate secure channel.

EPON, two-way master key, hash function, MAC frame, secure channel

Description

Key distribution method on EPON

1 is a view showing a schematic structure of an EPON to which the present invention is applied;

2 is a flow chart showing the flow of one embodiment of a key distribution method in an EPON according to the present invention;

3 illustrates a structure of a conventional MAC frame used in the data link layer.

4 is a diagram illustrating a structure of a MAC frame used for key distribution and management according to the present invention;

5 is a diagram showing the structure of an information key management frame among key management frames according to the present invention;

6A and 6B illustrate the structure of a key update request key management frame among key management frames according to the present invention;

7A and 7B illustrate a structure of a key update response key management frame among key management frames according to the present invention;

8 illustrates a structure of a key verification request key management frame among key management frames according to the present invention;

9 illustrates a structure of a key verification response key management frame among key management frames according to the present invention;

10 is a diagram illustrating the structure of a key verification confirmation key management frame among key management frames according to the present invention;

 11 is a state transition diagram of each procedure for the key distribution method according to the present invention;

12 is a flowchart illustrating a flow of an embodiment of a key update method according to the present invention, and

13 is a flowchart illustrating the flow of another embodiment of a key update method according to the present invention.

The present invention relates to a key distribution method, and more particularly, to a method for distributing keys without having to configure a secure channel within an Ethernet Passive Optical Network (EPON) section.

When entity A tries to deliver a message to entity B in a communication network, if the message is in danger of being stolen by any user during transmission, it must be encrypted before being transmitted to ensure the safety of the message. In general, the encryption techniques used for security are divided into symmetric key encryption and public key encryption. The two technologies differ greatly in encryption algorithms, and the key distribution method is also different.

First, symmetric key encryption is an encryption technique in which the key used for encryption and the key used for decryption are the same. For example, if entity A used K _C to encrypt a message, entity B must use K _C to decrypt the received encrypted message. Algorithms used for symmetric key encryption include DES (Data Encryption Standard) and AES (Advanced Encrypition Standard), and the lengths of keys used for each algorithm are 56 bits and 128 bits, respectively.

The longer the key, the more secure it is, but the longer it takes to process a message. At present, it is known that the key length is more than 128 bits in symmetric key encryption. The symmetric key algorithm has a short time to encrypt or decrypt a message, so most encryption modules use it as a security algorithm.

However, since symmetric key encryption must have the same key for each entity group to communicate with, N (N-1) / 2 keys are required if there are N entities in the communication network. In order to distribute such a key, there must be a key distribution center in the network, and each entity receives and uses a key of another entity that wants to communicate with the key distribution center through a predetermined secure channel. In addition, since the keys must be replaced periodically, there is a disadvantage in that the cost for distributing the keys becomes large.

Public key encryption is an encryption technique in which a key used for encryption and a key used for decryption are different. For example, if entity A used K _P to encrypt the message, then entity B that received it should use K _P 'to decrypt the message. If entity A creates K _P and K _P 'in the network and then discloses K _P to other entities on the network, other entities wishing to communicate with entity A encrypt with K _P and send a message to entity A.

Here, it has a K _P and K _P 'is the key that exists only as a pair, even if the public K _P K _P' It is characteristic that computationally impossible to find. This is due to the Rivest-Shamir-Adleman (RSA) algorithm used for public key encryption. Unlike symmetric key cryptography, public key cryptography requires two keys for each entity and is easier to distribute than symmetric key cryptography because there is no need to use a secure channel to distribute K _P used as a public key. The advantage is that fewer keys are distributed.

However, in order for the message encrypted by the RSA algorithm to be secured, the key length must be 1024 bits or more. Therefore, the RSA algorithm takes a long time to encrypt or decrypt a message, so that the RSA algorithm is rarely used as a message security algorithm in a communication network.

To apply security technology to the network layer, an encryption module and a key management module are required. The encryption module is a module that encrypts a message using an encryption algorithm and uses the symmetric key encryption or public key encryption technology described above. Each technology implements encryption using the keys provided by the key management module. The key management module manages keys to be provided to the encryption module. Key management includes key generation, storage, distribution, update, and revocation. In the case of using the symmetric key encryption technology, the key distribution is performed at the key distribution center through a secure channel. In the case of using the public key encryption technology, the key distribution is performed through the public channel.

An object of the present invention is to provide a key distribution method applied to a data link layer capable of securely distributing a key without having a separate security channel within an EPON section.

In order to achieve the above technical problem, an embodiment of a key distribution method in an EPON according to the present invention includes: exchanging first random values generated by the OLT and the ONU, respectively, to generate a unicast secure channel; Generating a bidirectional master key based on the exchanged first random value and a pre-distributed master key using a hash function; Exchanging second random values generated by the OLT and the ONU, respectively; And generating a temporary key based on the exchanged second random value, MAC addresses of the OLT and ONU, and the two master keys using a hash function.

In order to achieve the above technical problem, another embodiment of a key distribution method in an EPON according to the present invention includes: transmitting a first random value generated by an OLT to an ONU to create a broadcast secure channel; Generating a bidirectional master key based on the delivered first random value and a pre-distributed master key using a hash function; Delivering second random values generated by the OLT to the ONU; And generating a temporary key based on the delivered second random value, the MAC addresses of the OLT and ONU, and the bilateral master key using a hash function.

This allows the key to be distributed without having a separate secure channel in the EPON.

Hereinafter, with reference to the accompanying drawings will be described in detail the key distribution method in the EPON according to the present invention.

1 is a diagram illustrating a schematic structure of an EPON to which the present invention is applied.

EPON (Ethernet Passive Optical Network) is a network composed of a physical point-to-multi-type tree structure. Applying symmetric key cryptography security technology to these EPONs, the encryption module will not be able to avoid the complexity of key distribution even with fast execution times.

However, EPON is not a mesh structure, but logically has a point-to-point structure even though it has a physical point-to-many structure. That is, all optical network units (ONUs) 110, 112, and 11N are connected to one optical line terminal (OLT) 100. Thus, no effort is needed to distribute multiple keys to an entity, which is a disadvantage of symmetric key encryption.

For example, one ONU 110, 112, 11N needs only one key to communicate with the OLT 100, and the ONU 110 passes through the OLT 100 in order to communicate with the other ONU 112. Since it cannot be done, the destination uses the same key even if it transmits different data.

This is because the security technology in EPON is limited to security for a single link because its scope of application is the data link layer. Therefore, even if EPON uses symmetric key encryption technology, the number of keys required for encryption is the number of channels set by each ONU (110, 112, 11N) with the OLT 100, and the number of keys distributed when using public key encryption technology. Will be similar to In addition, the structural feature of the EPON is a key distribution in the form of one OLT 100 controls a plurality of ONU (110, 112, 11N).

When data is transmitted from the EPON, downlink data from the OLT 100 to the ONUs 110, 112, and 11N are broadcasted, and uplink data from the ONUs 110, 112, and 11N to the OLT 100 are unicasted.

In particular, downlink data cannot be physically broadcast even when transmitted with a single destination. Thus, a situation arises in which data is transmitted to an unintentional ONU. In addition, logically broadcast downstream data cannot prevent data from being sent to ONUs that are not allowed to connect. In such cases, security is needed to protect the message or to prevent misuse of the data in the EPON by any user.

Applying security technology to EPON requires an encryption module that encrypts messages and a key management module that provides keys to the encryption module. The key distribution method according to the present invention is a key distribution technique used by the key management module as a link security technique applied to the data link layer. Therefore, the key distribution method according to the present invention can be used in the key management module when link security is implemented in EPON.

The key provided by the key management module to the encryption module is generated in the OLT 100 or the ONUs 110, 112, and 11N and distributed to the OLT 100 or the ONUs 110, 112, and 11N. The key generated for security is periodically updated. What is needed is a key distribution method, and key distribution should be performed using the most secure key distribution technology.

The key distribution may be performed by using a secure channel provided by the encryption module or by separately configuring a secure channel in the key management module. However, when the encryption module operates only in one direction when using the secure channel provided by the encryption module, that is, only the data from the OLT 100 to the ONU (110, 112, 11N) is encrypted, and the ONU (110, 112, 11N) is used. If there is a case where the data to the OLT 100 is not encrypted, it is inevitable to configure a secure channel in the key management module.

However, if a separate security channel is configured in the key management module, the key management complexity is remarkable, because the key management module needs to separate a module that uses an encryption algorithm, such as an encryption module, and manage the key separately from providing the required key to the encryption module. Increases.

Therefore, the best way is not to use a secure channel for key distribution in the key management module. In view of such a situation, the present invention provides a method for securely distributing a key in EPON without using a separate secure channel for distributing a key.

2 is a flow chart showing the flow of one embodiment of a key distribution method in an EPON according to the present invention.

Referring to FIG. 2, the OLT generates a random value (Anonce) and transmits it to the ONU, and the ONU also generates a random value (Bnonce) and transmits it to the OLT or transmits the random value generated by the OLT to the ONU (S200). . OLT and ONU execute a hash function that inputs random value (Anonce or Bnonce) generated by itself, random value (Bnonce or Anonce) received from the other side and the same pre-distributed master key (MK: Master Key). A pairwise master key (PMK) is generated (S210).

The master key MK is a key that is pre-distributed to the OLT and ONU before the encryption operation proceeds, and the master key distribution can be distributed by various conventional methods.

The present invention uses a hash function PRF (Pseudo Random Function) as an algorithm for generating a key. The properties and characteristics of the hash function are as follows.

Hash Function Properties

1. Convert any finite length input bit stream x into a fixed length output bit stream H (x).

2. For a given H and x, it is easy to calculate H (x).

Hash Function Characteristics

1. It is impossible to calculate the input value for a given output.

2. It is computationally impossible to find another input that produces the same output for a given input.

3. It is computationally impossible to find any two different input messages that produce the same output.

If the output value of 160bit or more is used for the unidirectionality and collision avoidance of the PRF, it is difficult to find the key even through a total attack, so it has strong security. Here, the total attack is an attack method that calculates by substituting the numbers of all cases to find the key value. Therefore, an average of 2 ⁸⁰ or more attempts are required for an attacker to find a key.

After the two-way master key is generated, the OLT generates another random value (Anonce) and sends it to the ONU, and the ONU also generates another random value (Bnonce) and sends it to the OLT, or the OLT is another random value (Anonce). And Bnonce) is generated and transmitted to the ONU (S220). OLT inputs the random value (Anonce) generated by itself, the random value (Bnonce) received from ONU, or another random value (Bnonce) generated by itself, its own MAC address, the MAC address of ONU and both master keys. By performing a hash function to generate a temporary key (TK) (S230). ONU also generates a temporary key (TK) in the same way as OLT.

The temporary key is a session key, which is divided into a broadcast key (BK) for the broadcast temporary key and an initial value (IV) for the broadcast secure channel, and an AK (Aunthention Key) and a SAK (Secure Association) for the unicast temporary key. Key) and IV (Initial Value) for the unicast secure channel. Table 1 summarizes the functions of each key.

Key type function Authentication Key (AK) Used to authenticate OLT and ONU. BK (Broadcast Key) Encrypts broadcast data in OLT and decrypts it in ONU. SAK (Secure Association Key) Used to encrypt and decrypt unicast data between OLT and ONU. IV (Initial Value) Value used to initialize the algorithm used by the cryptographic module

The key generation method using the hash function PRF is as follows.

PMK = PRF (Anonce∥Bnonce∥MK)

TK = PRF (Anonce∥Bnonce∥Aaddr∥Baddr∥PMK)

here,

Pairwise Master Key (PMK): 16 bytes

Anonce: Random random value generated by A, 16 bytes

Bnonce: Random random value generated by B, 16 bytes

Temporal Key (TK): 64 bytes

Aaddr: A MAC address, 6 bytes

Baddr: B MAC address, 6 bytes

Since the key distribution method according to the present invention described with reference to FIG. 2 can avoid direct key delivery through the channel, it is not necessary to separately configure a secure channel for key delivery. If the key is transmitted through the secure channel without using this method, the risk of double exposure exists because the data encryption key is also exposed to the attacker. However, the present invention can avoid this risk.

If the temporary key TK is exposed to the attacker, the two-way master key PMK that generated the temporary key TK is not exposed, so the updated temporary key TK can be safely used. In addition, the two-way master key (PMK), which is difficult to expose, is also periodically replaced, thus providing stronger security. Since the master key (MK), which is the basis of key generation, has never been disclosed to the channel, it has the strongest security.

Since the present invention is a technique used in the data link layer, it uses a frame that is created and destroyed between the OLT and the ONU. An OAM frame exists as a MAC frame generated and destroyed in an EPON interval. The key distribution method according to the present invention also uses a slow protocol as in the OAM protocol.

Hereinafter, the MAC frames used in the present invention will be described with reference to FIGS. 3 to 10.

3 is a diagram illustrating a structure of a conventional MAC frame used in the data link layer.

Referring to FIG. 3, the conventional MAC frame 300 includes a destination address field (DA) 310, a source address field (SA) 320, and a length / type field ( 330, a data (Data / Pad) field 340 for recording data, and an FCS field 350 for checking an error of a frame.

4 is a diagram illustrating a structure of a MAC frame used for key distribution and management according to the present invention.

Referring to FIG. 4, the MAC frame 400 according to the present invention includes a destination address field (DA) 405, a source address field (SA) 410, and a length / type. ) Field 415, subtype field 420, flag field 425, code field 430, data / pad field 435, and FCS field 440 It includes.

A MAC frame suitable for the key management protocol according to the present invention will be referred to as a key management frame below, and each field of the key management frame will be described below.

By applying the rules of the slow protocol, the destination address field 405 has a value of "01-80-C2-00-00-02", and the length / type field 415 has a value of "80-09" indicating the slow protocol. Has The subtype field 420 uses "4" in 4-10 except for the value of 1-3 used previously.

Since the minimum length of the MAC frame (300 in FIG. 3) is 64 bytes, the data field should have a value of at least 43 bytes and a maximum of 107 bytes. Here, even if the maximum length of the MAC frame is 1522 bytes, since the maximum length of the frame used for the slow protocol is limited to 128 bytes, the key management frame 400 according to the present invention can extend the data field only up to 107 bytes.

The flag field 425 consists of 1 byte and the functions of each bit are shown in Table 2.

beat name Explanation 0 Local set done 0 = Local device does not have an encryption module or is not set 1 = Local device has an encryption module and is set One Remote set done 0 = no encryption module on remote device or not set 1 = remote device has encryption module and is set 2-7 reserved

The set done bit is divided into Local and Remote. For example, when the OLT transmits a key management frame to the ONU, the Local set done bit indicates the encryption module information of the OLT, and the Remote set done bit indicates the encryption module information of the ONU.

If the value of the set done bit is 0, it means that the encryption operation is not performed because there is no encryption module or the encryption setting between the OLT and ONU is not correct. If there is no encryption module, there may or may not be a key management module. That is, if there is no key management module, there is no response to the key management request. If there is a key management module but no encryption operation is performed, the set done bit is filled with "0" and the remaining bits are filled with "null". In both cases, the mode encryption module is in a state in which it cannot operate normally.

When the set done bit has a value of 1, it indicates that the encryption module is present and the encryption module is operable because the settings are correct. Therefore, when the Local set done bit and the Remote set done bit are "1" simultaneously, the encryption module can be actually operated.

The flag field 425 is configured to be included in every key management frame and processed as the first information about the frame. This allows the key management module to respond quickly to changes in the encryption module that occur during normal operation with the two set done bit values of the flag set to "1". That is, when the Local set done bit or the Remote set done bit is changed to "0", the operation of the encryption module should be stopped.

In addition, each time the key management frame is transmitted, the receiver transmits the state information of the encryption module on the receiving side to the remote set done. Therefore, the receiving side correctly manages the status information of the encryption module on the receiving side in the received frame. You can check.

The code field 430 distinguishes the types of key management frames by 1 byte, and the types of the key management frames according to code values are shown in Table 3 below.

Code value name Explanation One Information key management frame Configuration Information for Cryptographic Modules and Key Management Modules 2 Key update request key management frame Request a key update 3 Key update response key management frame Response to key renewal request 4 Key Validation Request Key Management Frame Key validation requirements 5 Key Validation Response Key Management Frame Response to key verification request 6 Key Validation Verification Key Management Frame Notice the success of key validation

5 is a diagram illustrating a structure of an information key management frame among key management frames according to the present invention.

Referring to FIG. 5, the structure of the information key management frame 500 is the same as that of the key management frame 400 of FIG. 4. However, in order to indicate the information key management frame, the value of the code field 530 is "1" (see Table 3), and the data field 535 includes key management module configuration information and encryption module configuration information 537 and 539. .

Configuration information recorded in the data field 535 is shown in Table 4.

beat name Explanation 0 Operating status 0 = encryption module off 1 = encryption module on 1-2 Encryption mode 0 = provide encryption only 1 = provide decryption only 2 = provide all 3-6 Encryption algorithm 0 = GCM-AES-128 1 = CCM-AES-128 2 = OCB-AES-128 3 = RSA 7-10 Key distribution algorithm 0 = no-Diffie-Hellman 1 = Diffie-Hellman 11-15 Reserved

If there is no encryption module, if the set done bit of the flag field 525 indicates "0", the configuration information is all filled with "null". However, if the encryption module is present and does not operate, even if the set done bit of the flag field indicates "0", if the operation status bit of the configuration information is "on", all the configuration information is filled.

The operation status bits of Table 4 are bits that check if the encryption module is actually present in the system. That is, the set done bit of the flag field may be 1 when the operation status bit is “on” and the remaining information of the configuration information is synchronized with each other. However, if the encryption module does not operate and the operation state information indicates "0", all remaining bits of the configuration information are filled with "null".

The encryption mode bits of Table 4 are bits for functions provided by the encryption module. Since the downlink is broadcast data while the uplink is unicast data, the EPON may not perform an encryption operation on the uplink data in some cases. Or, if necessary, the opposite can be the case. If the security module between OLT and ONU cannot be synchronized by processing the encryption mode information, the set done bit of the flag field is filled with "0".

The encryption algorithm bits in Table 4 are algorithms used when encrypting and decrypting data in the encryption module. In the example of Table 4, all of them are symmetric key algorithms except RSA. In some cases, the encryption module may have an independent module for operating a plurality of encryption algorithms. If the encryption algorithm information is processed and the security modules cannot be synchronized with each other, the set done bit of the flag field is filled with "0".

The key distribution algorithm bits in Table 4 are bits that convey the method used by the key management module for distributing keys. In Table 4, the two algorithms are described as examples, but this part constitutes a separate encryption channel for key distribution. Pointer to the algorithm information used in the key distribution encryption module.

When a separate encryption channel is configured for key distribution, the data field of the key management frame can be changed or a new key management frame can be defined and used. However, in the present invention, the key distribution algorithm is not a method of separately configuring an encryption channel by a modification of the Diffie-Hellman method. If the security module between the OLT and ONU cannot be synchronized by processing the key distribution algorithm information, the set done bit of the flag field is filled with "0".

6A and 6B illustrate a structure of a key update request key management frame among key management frames according to the present invention.

Referring to FIG. 6A, the structure of the key update request key management frame 600 is the same as that of the key management frame 400 of FIG. 4. However, the code field 630 includes a value "2" (see Table 3) indicating a key update request key management frame, and the data field 635 exchanges for the key update with the type 637 of the key to be updated. It includes a random value (Nonce) 639.

Encrypted messages can always be stolen by attackers, and message theft is the potential for the keys used for encryption to be exposed. Therefore, for security purposes, the key used for encryption should be replaced periodically.

The key update request key management frame 600 of Figs. 6A and 6B is used to update the temporary key TK and the two-way master key PMK, which should be updated periodically. Since the two-way master key (PMK) is not used for data encryption, the update period is relatively long. However, since the temporary key (TK) is used for data encryption and continuously exposed to the channel, the update period is short.

Here, the reason for periodically replacing the two-way master key (PMK) that is not used for data encryption is that the two-way master key (PMK) is used to replace the temporary key (TK), and the factor for generating the temporary key (TK) is This is for strong security cycles as they are exposed on the channel.

The key index field 637 of the data field 635 of the key update request key management frame 600 distinguishes the kind of key (PMK or TK) to be updated, and the Nonce field 639 is required to generate a key. Contains a random value. For example, if the key index field is "0", it means an update request of both master keys PMK, and if "1", it is an update of the temporary key TK.

6A is a frame used for unicast key update, and FIG. 6B is a frame used for broadcast key update. The unicast key is used for one-to-one communication between OLT and ONU, and the broadcast key is used for one-to-many communication with OLT and all ONUs connected to the OLT. Since the broadcast key should be equally distributed to all ONUs, the key is generated using only the random value generated by the OLT.

When the key update request key management frame 600 is transmitted, the key cannot be generated until the key update response key management frames (Figs. 7A and 7B) arrive from the partner. Key Update Response When a key management frame arrives, the key management module generates an update request target key recorded in a key index field using its random value (Anonce) and its relative random value (Bnonce). In the case of broadcast keys, Bnonce is also distributed in the OLT, so ONU does not generate random values.

7A and 7B illustrate a structure of a key update response key management frame among key management frames according to the present invention.

Referring to FIG. 7A, the structure of the key update response key management frame 700 is the same as that of the key update request key management frame 600 of FIG. 6A. However, the code field 730 includes a value "3" (see Table 3) indicating a key update response key management frame.

The key update response key management frame 700 is transmitted when the key update request key management frame 600 is received. The key index field 737 of the data field 735 of the key update response key management frame 700 distinguishes the types of keys to be updated (for example, 0: PMK, 1: TK), and the Nonce field 739 ) Is used to pass the value needed to generate a key.

After transmitting the key update response key management frame 700, the key management module updates the requested key by using the random value Anonce of the key update request key management frame 600 and its random value.

8 is a diagram illustrating a structure of a key verification request key management frame among key management frames according to the present invention.

Referring to FIG. 8, the structure of the key verification request key management frame 800 is the same as that of the key management frame 400 of FIG. 4. However, the code field 830 includes a value "4" (see Table 3) indicating a key verification request key management frame, and the data field 835 includes a type 836 of the key to be verified and data for verification ( 837,838).

Even if the key is updated using the key update request and response key management frames 600 and 700, the present invention does not transmit the key directly, so it is necessary to confirm the correct delivery.

Key Verification Request The key management frame 800 transmits the index 836 of the key to be verified and the random values (Anonce, Bnonce) 837 and 838 used to generate the key. To verify the key, a verification key (VK) is derived as shown in Equation 2 below.

VK = PRF (Anonce∥Bnonce∥K _i )

Where K _i is the type of key to be verified (i: (0) AK, (1) BK, (2) SAK)

The key management module on the transmitting side generates the verification key VK after transmitting the key verification request key management management frame, and waits for the reception of the key verification response key management frame (Fig. 9).

9 is a diagram illustrating the structure of a key verification response key management frame among key management frames according to the present invention.

Referring to FIG. 9, the structure of the key verification response key management frame 900 is the same as that of the key management frame 400 of FIG. 4. However, the code field 930 includes "5" (see Table 3) indicating a key verification response key management frame.

Key Verification Request The key management frame is transmitted including all the factors that can generate the verification key (VK). Accordingly, the receiving key management module that receives the key verification request key management frame generates a key verification response key management frame (FIG. 10), and the index 937 of the verification target key and the generated verification key (VK) 939 ), Including Generation of the verification key is generated through equation (2).

10 illustrates a structure of a key verification confirmation key management frame among key management frames according to the present invention.

Referring to FIG. 10, the structure of the key verification confirmation key management frame 1000 is the same as that of the key management frame 400 of FIG. 4. However, the code field 1030 includes a value "6" (see Table 3) indicating a key verification confirmation key management frame.

After the key verification request / response key management frame (800,900) is exchanged to generate and verify the key, the requesting key verification side forwards the verification result of the key to the receiver. This is because if the key verification is performed after the key is updated, the key can be updated only after verifying the verification result. However, it is not necessary to pass the key validation confirmation key management frame unless key validation is required due to key update.

The key verification confirmation key management frame 1000 transmits the key verification response key management frame 900 after receiving the key verification response key management frame 900. If the key verification confirmation key management frame 1000 is received and the result value is not successful, the key should not be updated.

The key management frames described so far are all transmitted in the EPON section without being encrypted. As mentioned earlier, the security characteristic of PRF is that even if the information to be delivered in the key management frame is leaked by the attacker, the key cannot be found within the valid time.

11 is a diagram illustrating a state transition diagram of each procedure for the key distribution method according to the present invention.

Referring to FIG. 11, a procedure for key distribution includes three processes of key update 1100, key distribution 1110, and key verification 1120.

The key update procedure 1100 generates a key and executes the key distribution procedure 1110 to distribute the generated key when the key update cycle is reached. The key distribution procedure 1110 distributes the keys, and executes the key verification procedure 1120 when the key distribution is completed. The key verification procedure 1120 executes the key update procedure 1110 after the key verification is completed. The key update procedure 1100 waits for the next distribution cycle after updating the verified key.

12 is a flowchart illustrating the flow of an embodiment of a key update method according to the present invention.

Referring to FIG. 12, after a key for encryption is generated and distributed to OLT and ONU in EPON, a key update timer is operated (S1200). When a predetermined time has elapsed and the key update timer is completed (S1205), the key distributing side (OLT or ONU, hereinafter referred to as sending side) transmits the key update request key management frame to the other side (OLT or ONU, hereinafter called receiving side). (S1210).

When the transmitting side receives the key update response key management frame from the receiving side in response to the key update request key management frame (S1215), the transmitter generates a key verification request key management frame and transmits it to the receiving side (S1220).

When the transmitting side receives the key verification response key management frame from the receiving side in response to the key verification request key management frame (S1225), it checks the key verification response key management frame to determine whether the key verification result is correct (S1230). If the key verification succeeds, the transmitting side transmits the key verification confirmation key management frame to the receiving side and performs key update (S1235).

The transmission and reception of the above key management frame is performed through the MAC frame of the slow protocol.

13 is a flowchart illustrating the flow of another embodiment of a key update method according to the present invention.

12 is a flowchart showing the flow of the key updating method from the standpoint of the side requesting the key update, whereas FIG. 13 is a flowchart showing the flow of the key updating method from the standpoint of the side requesting the key update.

Referring to FIG. 13, when a key update request key management frame is received (S1300), a key update response key management frame is generated and transmitted (S1305). When the key verification request key management frame is received (S1310), a key verification response frame is generated and transmitted (S1315).

When the key verification confirmation key management frame is received (S1320), the key is updated (S1325).

So far I looked at the center of the preferred embodiment for the present invention. Those skilled in the art will appreciate that the present invention can be implemented in a modified form without departing from the essential features of the present invention. Therefore, the disclosed embodiments should be considered in descriptive sense only and not for purposes of limitation. The scope of the present invention is shown in the claims rather than the foregoing description, and all differences within the scope will be construed as being included in the present invention.

The key distribution method according to the present invention is applied to the EPON as part of the network security technology, it is possible to distribute the key used in the encryption module securely and efficiently through the key management module in the OLT and ONU of the EPON, the specific effect is As follows.

First, there is no need to configure a separate secure channel for key distribution by using PRF.

PRF is a well-known hash function with unidirectionality and collision avoidance. It is cryptographically stable when the output value is set to 160 bits or more. The present invention avoids direct key delivery in the channel by using a key distribution method using PRF. Therefore, since a separate security channel for key distribution is not required, the complexity of the key management module can be reduced.

Second, it uses a slow protocol.

Since the slow protocol is a protocol using MAC frames in the data link layer, the present invention using the slow protocol does not leak key management frames out of the EPON interval. Therefore, the key management frame cannot be obtained outside the EPON, so it is safe within the EPON. In addition, the slow protocol limits the maximum number of frames that can be transmitted in one second and the frame length to 128 bytes, which does not affect the amount of traffic in the EPON.

Third, key distribution is achieved using a relatively simple protocol.

The present invention performs five steps of key update request / response, key verification request / response, and key verification verification while performing key distribution using a key management protocol. In this case, since the information transmitted in the frame is composed of a simple algorithm having only a simple input value and an output value, the complexity of the protocol can be reduced.

In addition, when the security technology is applied to the data link layer in a general network, the present invention has the scalability to be used in the key management module independently of the algorithm of the encryption module. If you install a device in the network and only set the master key between the devices, the key distribution will be done automatically according to the key distribution procedure. In addition, in the case of a shared LAN having a network structure, in order to apply the present invention, a central control device such as an OLT that serves as a key distribution center is required.

Claims (8)

Exchanging first random values each generated by the OLT and the ONU to generate a unicast secure channel through a MAC frame of a slow protocol including a first key index indicating a bidirectional master key in the unicast secure channel. step; Generating a bilateral master key based on the exchanged first random value and a pre-distributed master key using a hash function; Exchanging second random values generated by the OLT and the ONU, respectively, through a MAC frame of a slow protocol including a second key index indicating a temporary key; Generating a temporary key corresponding to the second key index based on the exchanged second random value, MAC addresses of the OLT and ONU, and the two master keys using a hash function; And And updating the bilateral master key or the temporary key by using the first key index and the second key index at predetermined intervals. Passing a first random value generated by an OLT to create a broadcast secure channel to an ONU via a MAC frame of a slow protocol including a first key index indicating a bidirectional master key in the broadcast secure channel; Generating a bilateral master key based on the delivered first random value and a pre-distributed master key using a hash function; Transmitting a second random value generated by the OLT to the ONU through a MAC frame of a slow protocol including a second key index indicating a temporary key; Generating a temporary key corresponding to the second key index based on the transferred second random value, the MAC addresses of the OLT and ONU, and the two master keys using a hash function; And And updating the bilateral master key or the temporary key by using the first key index and the second key index at predetermined intervals. The method according to claim 1 or 2, And the temporary key is used as an authentication key between the OLT and the ONU, an encryption key of broadcasting data, an encryption key of unicast data, and a value used to initialize an encryption module algorithm. delete delete The method of claim 1, wherein the key update step, One of the OLT and the ONU transmits a key update request frame including an update target key type and a third random value for key update, to a counterpart, and includes a fourth random value for key update from the counterpart. Receiving a frame to generate a new key; And The one side transmits a key verification request frame including the key type information to be updated, the third random value, and the fourth random value to the counterpart, and transmits the third random value and the fourth random value from the counterpart. Receiving a key verification response frame containing a verification key generated on the basis; Key distribution method in EPON. The method of claim 6, And transmitting, to the counterpart, a key verification confirmation frame including a verification result performed using the verification key included in the key verification response frame at the one side. The method according to claim 1 or 2, The OLT and the ONU further comprises the step of transmitting and receiving a MAC frame containing configuration information of each encryption module and key management module; key distribution method in the EPON.

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