Proposed text to close issue 20

(1)

Section 4.2.4, Returning Computed Keys, ws-trust-1.3-spec-ed-01

[quote]
The key is computed using P_SHA1
from the TLS specification to generate
a bit stream using entropy from both
sides. The exact form is:
key = P_SHA1 (EntREQ, EntRES)
[quote]

ADD the following: It is RECOMMENDED that EntREQ be a string of length 
at least 128 bits.

(2)

line 675-677:  
[quote]
The P_SHA-1 function has two parameters - secret
and value.  We
concatenate the label and the seed
to create the value. 
That is:

    P_SHA1 (secret, label + seed)
[quote]

ADD the following: It is RECOMMENDED that secret be a string of length at least 128 bits.
[quote]