I have seen this term in many docs on IKE and ISAKMP. These docs seems to be written for Security experts but not everyone who needs to setup an IPSec tunnel needs to be a security expert :-) So what exactly do they mean with this ?
What is the exact meaning of “Keying material”?
Keying material is a more general and fancy term for "secret keys of (unspecified) format, length and amount", where the "unspecified" part may be clarified depending on configuration or is just outsourced to other sections of the paper.
- It is this general to include things like shared Diffie-Hellman secrets (which are not suitable as symmetric keys), which have more structure than normal keys.
- It provides a nice sense of abstraction. For example I might say: You feed your keying material into a KBKDF (like HKDF) and use this as the input to TLS-PSK, without ever having to know how you established that material (DH? ECDH? PSK?)
- It allows to not care about the actual format or location of keys (is the key in software, on a card or in a HSM and how is it stored in detail?) as it just tends to be used for "you (but nobody else) have access to this".
- It allows to include multiple keys which are needed to access one particular system (e.g. if you'd need two keys to access something you'd just say keying material instead of "key a and b").