Expand keys to auth, signing, and encryption. Also cite BT spec.

3.C.10.3 defines the authentication procedure as basically insisting that pairing has happened with MITM protection enabled. It's not an extra key. The set of keys is actually defined in 3.H.2.4.1, where we have the IRK, CSRK, and LTK. The IRK is used to get past the Privacy Feature and identify a device, so we probably shouldn't leak it, but that's going to take some extra wording in addressing #32. The CSRK is used for signing data, and the LTK is used to generate session encryption keys.

Maybe "addressing, data signing, or encryption keys" to match the first paragraph of 3.H.2.4.1? Only the encryption keys are really relevant to the rest of this paragraph.