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WG Last Call: draft-ietf-ipsec-esp-v3-05
I have a few comments on the updated ESP specification.
1. Please delete the last line of the Abstract. In my opinion, pointers
to subsequent sections belong in the Introduction, not the Abstract.
2. Please move the last two paragraphs of the Introduction to the
beginning. This will tell the reader the material that the expected to be
understood before they get too deep, and it will define MAY. SHOULD, MUST,
and so on before they are used.
3. The last paragraph on page 4 includes:
Typically this binding is effected through the use of a shared,
symmetric key, but an asymmetric cryptographic algorithm also may be
employed, e.g., to sign a hash.)
Digitally signing individual packets should not be encouraged. The
performance ramifications, both computational and packet bloat, are
extreme. I suggest dropping the second half of the sentence. Just do not
bring it up.
4. The first full paragraph at the top of page 5 includes:
Although confidentiality and integrity can be offered independently,
most ESP use typically will employ both services, i.e., packets will
be protected with regard to confidentiality and integrity.
5. The following paragraph appears on the second half of page 7:
When any combined mode algorithm is employed, the algorithm itself is
expected to return both decrypted plaintext and a pass/fail
indication for the integrity check. For combined mode algorithms, the
ICV that would normally appear at the end of the ESP packet (when
integrity is selected) is omitted. It is the responsibility of the
combined mode algorithm to encode within the payload data an ICV-
equivalent means of verifying the integrity of the packet.
I consider CCM (see draft-ietf-ipsec-ciph-aes-ccm-03) to be a combined
mode. The referenced specification makes use of the ICV field. Therefore,
I propose two changes:
- Please replace "is omitted" to "may be omitted"
- Please change "It is the responsibility of the combined mode
algorithm ..." to "When the ICV is omitted and integrity is selected, it is
the responsibility of the combined mode algorithm ..."
6. Figure 2 include "IV (optional]. "
7. Below Figure 2, the following paragraph appears:
If a combined algorithm mode is employed, the explicit ICV shown in
Figures 1 and 2 is omitted (see Section 126.96.36.199 below). Since
algorithms and modes are fixed when an SA is established, the
detailed format of ESP packets for a given SA (including the Payload
Data substructure) is fixed, for all traffic on the SA.
s/is omitted/may be omitted/
8. In Table 2, the ICV row should be "O" in the "Requ'd" column.
9. The first sentence in section 2.2.1, has the flavor of a new option
that is under development, rather than one that is ready to be
finalized. I propose an alternative:
To support high-speed IPsec implementations, extended sequence
numbers SHOULD be implemented.
10. At the beginning of section 2.4, the following sentence is followed by
two bullets. Something is not quite right.
Three factors require or motivate use of the Padding field.
11. Please reword the paragraph in section 2.8 to permit the ICV field to
be present when a combined mode is employed, which is consistent with the
wording used in section 3.2.3.
12. Please reword the 4th bullet following the paragraph numbered 3 in
section 188.8.131.52 to permit the ICV field to be present when a combined mode
13. I am confused by "DISCUSSION" in section 184.108.40.206.