RFC Errata
RFC 4543, "The Use of Galois Message Authentication Code (GMAC) in IPsec ESP and AH", May 2006
Source of RFC: IETF - NON WORKING GROUPArea Assignment: sec
See Also: RFC 4543 w/ inline errata
Errata ID: 3643
Status: Verified
Type: Technical
Publication Format(s) : TEXT
Reported By: Michael Bowler
Date Reported: 2013-06-06
Verifier Name: Sean Turner
Date Verified: 2013-08-14
Section 4 says:
In AUTH_AES_GMAC, the AH Authentication Data field consists of the IV and the Authentication Tag, as shown in Figure 5. Unlike the usual AH case, the Authentication Data field contains both an input to the authentication algorithm (the IV) and the output of the authentication algorithm (the tag). No padding is required in the Authentication Data field, because its length is a multiple of 64 bits.
It should say:
In AUTH_AES_GMAC, the AH Authentication Data field consists of the IV and the Authentication Tag, as shown in Figure 5. Unlike the usual AH case, the Authentication Data field contains both an input to the authentication algorithm (the IV) and the output of the authentication algorithm (the tag). In IPv6, padding of 4 octets is required to bring the AH header to a multiple of 64-bits. No padding is required for IPv4.
Notes:
The original text fails to consider the rest of the AH header which is 12 octets plus the authentication data field.