!!! Overview
The [{$pagename}] is a value is:
* generated by the [user-agent]
* [Encrypted|Encryption] by the [user-agent] (referred to as the [EncryptedPreMasterSecret] in some of the [RFCs])
* Communicated to the server in the [ClientKeyExchange] 
* used by the [user-agent] and the server to [Derive the Master Secret].

Before the [ClientKeyExchange], anyone listening in on the traffic can know this all of this as well (as evidenced because we looked using Wireshark captures). 

Now we need to create a random secret key that an eavesdropper/[attacker] can not figure out.

The [user-agent] generates the 48-byte [{$pagename}] by concatenating the protocol version which must match the value sent previously in the [ClientHello] message and 46 bytes that the [user-agent] generates randomly (46 bytes). The [user-agent] is supposed to get these 46 bytes from a cryptographically secure [Pseudorandom number generator].

The 46 byte [{$pagename}] random value that’s generated is not used directly, but it’s very important to keep it secret since a lot of things are derived from it.

The length of the entire [{$pagename}] will vary depending on key exchange method.

!! More Information
There might be more information for this subject on one of the following:
[{ReferringPagesPlugin before='*' after='\n' }]