Group temporal key is used to encrypt all broadcast and multicast traffic between an access point and multiple client devices. PTK is dependent on another high-level key PMK (pairwise master key) which is discussed below. PRF is a pseudo-random function which is applied to all the input. MAC addresses of supplicant (client device) and MAC address of authenticator (access point). PTK = PRF (PMK + Anonce + SNonce + Mac (AA)+ Mac (SA))Īnonce is a random number generated by an access point (authenticator), Snonce a random number generated by the client device (supplicant). To generate PTK, client device and access point need the following information. PTK is unique between a client station and access point. Pairwise Transient key is used to encrypt all unicast traffic between a client station and the access point. I will start by talking about the keys which are generated during the 4-way handshake and towards the keys and other variables needed in order to generate these keys. These are the few keys we will be discussing… I would say don’t be scared of these terminologies.

Let’s see what terminologies we might come across to understand 4-way handshake. If you do not want to get confused about the terminologies used in 4-way handshake then let’s have a quick look. These keys which are generated through 4-way handshake are generated by some source key material which will be discussed later. The 4-way handshake is the process of exchanging 4 messages between an access point (authenticator) and the client device (supplicant) to generate some encryption keys which can be used to encrypt actual data sent over Wireless medium. Shall I just describe 4-way handshake which can be found everywhere on the web or shall I do a deep dive? Reason for me to write is to make it easier to understand for non WiFi people who can just read and understand because sometimes different terminologies used in this process can be confusing. I was thinking to write about the 4-way handshake and started to think that from where I should start writing.

Packet capture tool three way handshake