[GPON Technical Posts 11] Line Encryption Technology

Hello, everyone!

In the GPON system, the OLT broadcasts downstream data to all ONUs. Therefore, downstream data may be received by unauthorized ONUs, causing security risks.

To solve this problem, the GPON system uses the AES-128 encryption algorithm to encrypt plaintext data packets and broadcasts them in the ciphertext. The following figure shows the line encryption process. In short, the AES-128 algorithm uses a key to change 128-bit plaintext data into another 128-bit ciphertext data for broadcasting by using a series of mathematical operations. Then, the receiving end uses a key to decrypt the ciphertext. The AES-128 algorithm uses 128 bits in both plaintext and ciphertext with the following advantages: 

1. No extra overhead on the communication line and no impact on bandwidth efficiency; 

2. No increase in transmission delay. These advantages are very beneficial to the GPON system.

Line encryption process

Key Exchange and Switchover

In addition, the GPON system periodically exchanges and updates the AES keys, which further improves the communication security. 

1. The OLT initiates a key change request, and an ONU responds to the request and sends the new key to the OLT.

2. After receiving the new key, the OLT switches the key and uses the new key to encrypt the data.

3. The OLT notifies the ONU of the frame number of the new key by related commands.

4. After receiving the frame number of the new key, the ONU switches the check key in the corresponding data frame.

Now, do not hesitate to read through the post and give us your correct answers. If you have any difficulty understanding the content or want to learn more about the GPON technology, please leave a message and reply to the post. We are looking forward to your comments. 

Answers for the previous session:  C          

Questions for this session:  

Which of the following statements about Line encryption are incorrect?

A. The GPON system uses the Advanced Encryption Standard 128 (AES128) algorithm to encrypt the data packets 

B. The line encryption algorithms used in GPON systems will increase overhead 

C. The line encryption algorithms will prolong transmission delays.

D. the GPON system aperiodically exchanges and updates the AES keys

[GPON Technical Posts 10] Error Correction Technology: FEC

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Mainstream OLT, MDU, and ONT products that support GPON features include:

OLT: MA5800, EA5800, MA5680T, MA5600T

MDU: MA5633, MA5818, EA5821, MA5671

ONT: HG8240, HG8010H, HG8040, EG8080P, EG8040P

Thanks.