What is PMK in WiFi?
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.
What is opportunistic key caching?
Opportunistic Key Caching (OKC) is an enhancement of the WPA2 Pairwise Master Key ID (PMKID) caching method, which is why it is also named Proactive or Opportunistic PMKID Caching. This is required to generate new encryption keys every time a client reassociates with APs.
Which four options are valid fast roaming techniques?
To consistently safeguard and ensure fast roaming, a network might also adopt any of the four following techniques: Pre-Master Key (PMK) Caching, Pre-Authentication, Opportunistic Key Caching (OKC) and the IEEE 802.11r standard.
How can master key be established in 802.11 I?
Master key establishment can occur either manually via configuration or dynamically via the 802.1x protocol using EAP. After master keys are established, two parties perform key exchange to generate the transient keys they will use for the session.
What is PMK caching?
PMK caching allows the client to skip 802.1X authentication to any AP to which it has previously authenticated (only the 4-way handshake is required). PMK Caching is the method defined in the 802.11i specification, which also defined WPA2.
How is PMK generated in WPA2?
Pairwise master is key generated from master session key (MSK). In case of WPA2/PSK when device authenticates with access point the PSK becomes PMK. Point to Remember: PMK resides on all stations as in AP and client devices, so we do not need to share this information.
What is OKC in Aruba?
5. Under Fast Roaming select the Opportunistic Key Caching (OKC) checkbox to enable OKC. OKC is a technique available for authentication between multiple APs in a network where those APs are under common administrative control.
What key is PMK drive in?
Explanation: If a PSK is used then the PSK becomes the PMK; if an MSK is used, then the PMK is derived from the MSK using truncation. MSK – Master shared key. Explanation: The pairwise transient key (PTK) is derived from the Pairwise master Key (PMK).
What is 802.11 i and what aspect of Wlans does it deal with?
802.11i provides frame level encryption, authentication, and integrity protections for WLAN traffic. It also provides mutual authentication mechanisms based on the 802.1x protocol and Pre-Shared Key (PSK) methods.
How is PMK derived?
PMK is derived from MSK seeding material. PMK is first 256bits (0-255) of MSK. It can be derived from an EAP method or directly from a PresharedKey(PSK).
Can you use pmkid caching with 802.11k?
From discussions I’ve had with some Aruba engineers, it sounds like Apple’s implementation of OKC is spotty at best across the board on all platforms. However, documents such as this one suggest that PMKID caching, 802.11r, and 802.11k are all supported.
How does PMK caching AP work in CWSP?
In PMK Caching AP & client station maintain PMKSA for a period of time while a client station roams to a target AP & establishes a new PMKSA.Below shows the PMK caching packet flow (page 258 of CWSP Official Study Guide) As shown in the above figure, when client associate with an original AP and create an original PMK#1.
Which is fast secure roaming method for 802.11?
Pairwise Master Key ID (PMKID) caching, or Sticky Key Caching (SKC), is the first fast-secure roaming method suggested by the IEEE 802.11 standard within the 802.11i security amendment, where the main purpose is to standardize a high level of security for WLANs.
Do you need to reauthenticate a cached PMK?
If the client station decides to roam to target AP, the client does not need to reauthenticate & create new PMK as preauthenticated cached PMK already exists. So both can do 4-Way Handshake without EAP authentication process. Typically if AP support “preauthentication” it would advertise it via RSNIE in the beacon frames.