I'm trying to learn how ephemeral keys in WPA2 4-way handshake are derived.
Starting from 4 EAPOL packets sniffing, I successfully derived
SNonce, and knowing ASCII-PSK and the SSID.
PTK I derived, by splitting it, the
KCK (128bit), the
TK for ENC (128bit) and the
I'm stuck in a
If I understood correctly, the
GTK is transmitted encrypted from AP to ST in WPA Key Data field using the chiper suite described in first field of Key Information, in my case "AES Cipher.
In WPA2 AES is used in CTR mode for confidentiality, so i tried to decrypt the Key Data using OpenSSL, using
KEK as key and filed Key IV as
IV. I obtain
6c 1b 11 38 1f 8e 01 ee e1 d0 7b [...] from decryption, but reading the IEEE 802.11 I saw that the first Key Data's octect in EAPOL Key Frame is Type and should be
0xdd, so decryption fails.