Requirement about key wrapping

[randomstuff]

Received this feedback form Bart Preneel:

I would add a note stating that a symmetric key should always be wrapped by a key of at least the same length in bits.

[tghosth]

@randomstuff where would this fit in? Does this need to be a requirement?

[randomstuff]

@tghosth: I don't know :)

Very-strawman proposal:

6.4.X Verify that when a symmetric key is encrypted by another key, this key encryption key has at least as much entropy as the protected key.

Questions:

• Do we need to say "key wrap" or is my wording OK?
• I said "when symmetric key is encrypted" but I think this should apply to private keys as well, isn't it?
• I replaced "least the same length in bit" by "at least as much entropy", is this OK?

[tghosth]

I think keep this in the appendix as it is more of an implementation detail...