Thread Client Hello question

[likeli]

My customer is evaluating Thead stacks on KW41.

From Sniffer log, they found there is 330 bytes of “unknown extension” in the Client Hello message. Does anyone know what’s this for? Is it possible to remove it to reduce payload size of wireless communication?

Also, what’s the 168 bytes data in the Server Key Exchange message? Is it public key, or a & b?

gogoer​

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[haidong_zheng]

Please refer https://tools.ietf.org/html/draft-hao-jpake-01

Client hello “unknown extension”  format  as below:

Extension jpake_key_kp_list:

Length:(330)dec (2 bytes)

octet string KP_X1:... (165bytes)

octet string KP_X2:...  (165bytes)

Server key Exchange message format as below:

/* Server Key Exchange format:

  struct

{

   curve_type: 0x03 (1 byte)

   namedcurve: 0x0017 (2 bytes ->secp256)

   jpake_key_kp:

octet string KP_Xs:... (165 bytes)

}ServerKeyExchange

*/