Evaluation: draft-blumenthal-aes-usm-07

[Russ Housley <housley@vigilsec.com>]

I have three DISCUSS comments:

1.  In section 1.1, a normative reference to the NIST FIPS that defines 
AES.  I suggest:

    The main goal of this memo is to provide a new privacy protocol for the
    USM based on the Advanced Encryption Standard (AES) [FIPS-AES].

2.  The first paragraph in section 4 says:

    The security of the cryptographic functions defined in this document
    lies both in the strength of the functions themselves against various
    forms of attack, and also, perhaps more importantly, in the keying
    material that is used with them.  The recommendations done in Section
    1.3 MUST be followed to ensure maximum entropy to the selected
    passwords, and to protect the passwords while stored.

However, the referenced section 1.3 does not contain any MUST 
statements.  Either change the statements in section 1.3 to MUST, or change 
the MUST in section 4 to SHOULD.

3.  The second paragraph in section 4 says:

     For information regarding the necessary use of random IV values, see
     [CRYPTO-B].

The document properly requires unique IVs for each encryption.  Given the 
mode that is being used, unique IVs ought to be discussed in this paragraph 
too.

I have one additional editorial COMMENT:

In section 3.1, please remove the dash at the front of each 
paragraph.  Alternatively, treat it as a bulleted list by adding an 
introduction sentence.