How is PMK derived?
After the PSK or 802.1X authentication, a shared secret key is generated, called the Pairwise Master Key (PMK). In PSK authentication, the PMK is actually the PSK, which is typically derived from the WiFi password by putting it through a key derivation function that uses SHA-1 as the cryptographic hash function.
How PMK is generated from MSK?
The MSK is generated either through a password or through 802.1X/EAP authentication. From the MSK, the pairwise master key (PMK) is generated and installed on the supplicant and the A/AS. From the master keys, a set of temporal keys are generated by which subsequent data transmissions will be encrypted.
What is PMK key?
Pairwise Master Key
Pairwise Master Key. A PMK is a cryptographic key which is used to derive lower level keys. Networks based on technologies such as UMTS and WiMAX use PMK as part of their relative security procedures.
What is PMK in WiFi?
Described in the 802.11i standard (section 8.4. 1.2. 1), there exists a methodology by which clients undergoing an 802.1X authentication process can skip the EAP exchange whilst roaming between APs. This technique is known as PMK (Pairwise Master Key) caching.
What is PMK in 4-way handshake?
PMK is generated by encrypting the password and then send over by PTK. Here MIC needs to validate the code at Access Point and at Client. That means MIC carries the encrypted password which was created by KCK (key confirmation key). Now let’s say using aireplay we capture the handshake and CAP file is stored offline.
What does the 802.11 i standard cover?
802.11i is a standard for wireless local area networks (WLANs) that provides improved encryption for networks that use the popular 802.11a, 802.11b (which includes Wi-Fi) and 802.11g standards. However, AES requires a dedicated chip, and this may mean hardware upgrades for most existing Wi-Fi networks. …
How does an access point generate a PTK?
Message1: access point sends EAPOL message with Anonce (random number) to the device to generate PTK. Don’t forget client device knows Ap’s MAC because its connected to it. It has PMK, Snonce and its own MAC address. Once it receives Anonce from access point it has all the inputs to create the PTK.
Which is Group Temporal Key used in PTK?
PTK is dependent on another high-level key PMK (pairwise master key) which is discussed below. Group temporal key is used to encrypt all broadcast and multicast traffic between an access point and multiple client devices. GTK is the key which is shared between all client devices associated with 1 access point.
Which is the second level key in MSK?
The second level key is generated from MSK is PMK and GMK. PMK is used to generate PTK and GMK is used to create GTK. Third level keys are the actual keys used for data encryption. Once we understand important keys and how they are generated now let’s have a look on an actual 4-way handshake.