Eric:
1. Section 2.1.2 in the paragraph on pubInfo: There is a description that
appears to say CMS defined UserKeyingMaterial as a 512-bit value. There are
two problems with this: a) CMS does not say anything about the length of ukm
and b) no justification is shown here for a length of 512-bits. Is this a
magic length?
I'm trying to remember myself. ISTR that some previous CMS version
had 512 bits. I'm not fixated on this number by any means.
IIRC, KEA uses 512 bits.
You are comparing apples and oranges. KEA has a UKM value, bit it is 1024
bits long, and it is not an input to a hash function.
Again, 512 bits is the SHA-1 block size, so it is the maximum entropy that
can be inserted in this manner.
Russ