3.1.5.5.2.1 PEAP Tunnel Key (TK)

The PEAP Tunnel Key (TK) is calculated using the first 60 octets of the (secret) key material generated, as described in the EAP-TLS algorithm (see [RFC5216] section 2.3). More explicitly, the TK is the first 60 octets of the Key_Material, as specified in [RFC5216]: TLS-PRF-128 (master secret, "client EAP encryption", client.random || server.random).