to the status quo ante. The primary application currently envisioned for the 802.11r standard is voice over IP (VOIP) via mobile phones designed to work with wireless Internet networks, instead of (or in addition to) standard cellular networks. Fast BSS Transition IEEE 802.11r specifies fast Basic Service Set (BSS) transitions between access points by redefining the security key negotiation protocol, allowing both the negotiation and requests for wireless resources (similar to RSVP but defined in 802.11e) to occur in parallel. The key negotiation protocol in 802.11i specifies that, for 802.1X-based authentication, the client is required to renegotiate its key with the RADIUS or other authentication server supporting Extensible Authentication Protocol (EAP) on every transition, a time-consuming process. The solution is to allow for the part of the key derived from the server to be cached in the wireless network, so that a reasonable number of future connections can be based on the cached key, avoiding the 802.1X process. A feature known as opportunistic key caching (OKC) exists today, based on 802.11i, to perform the same task. 802.11r differs from OKC by fully specifying the key hierarchy. Protocol operation The non-802.11r BSS transition goes through six stages: Scanning – active or passive for other APs in the area. Exchanging 802.11 authentication messages (first from the client, then from the AP) with the target access point. Exchanging reassociation messages to establish connection at target AP. At this point in an 802.1X BSS, the AP and Station have a connection, but are not allowed to exchange data frames, as they have not established a key. 802.1X pairwise master key (PMK) negotiation. Pairwise transient key (PTK) derivation – 802.11i 4-way handshake of session keys, creating a unique encryption key for the association based on the master key established from the previous step. QoS admission control to re-establish QoS streams. A fast BSS transition performs the same operations except for the 802.1X negotiation, but piggybacks the PTK and QoS admission control exchanges with the 802.11 Authentication and Reassociation messages. Problems In October 2017 security researchers Mathy Vanhoef (imec-DistriNet, KU Leuven) and Frank Piessens (imec-DistriNet, KU Leuven) published their paper "Key Reinstallation Attacks: Forcing Nonce Reuse in WPA2" (KRACK). This paper also listed a vulnerability of common 802.11r implementations and registered the CVE identifier CVE-2017-13082. On August 4th, 2018 researcher Jens Steube (of Hashcat) described a new technique to crack WPA2 and WPA PSK (pre-shared key)