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swIPe stuff
Perry,
The IAB policy on cryptography is consistent with the general
thurst of your observation, i.e., we have adopted a stance that calls
for the use of cryptography to provide high quality security as
applicable throughout the Internet, irrespective of national policies.
However, mindful of international (not just U.S.) controls (export and
internal use) on crypto, we also suggest using crypto in a focused
way. Thus, where crypto for authentication/integrity can achieve
security goals and encryoption for confidentiality is not required, we
advocate use of crypto in the former fashion. Some countries are more
restrictive about what forms of crypto their citizens can easily use
within their own country. Not calling for crypto for confidentialtiy
where crypto for authentication and integrity will suffice facillitates
interoperable, international communication.
In terms of integrity checks, my point was that strong checks,
e.g., hashes, are really required. This is not what we put in non-
security protocols, and so use of encryption without security-
oriented integrity checks is dangerous. Use of the integrity checks
alone is a good approach for circumstances where confidentiality is
not required.
As for OFB being a strange case, use of CBC has a different,
but analogous set of problems for the last enciphered block. Even a
mode like CBC has some subtle vulnerabilities, if used with a weak
integrity check like the IP checksum. The best bet is use of a good
hash function, either in conjunction with encryption, signed, or with
a secret seed quantity.
Steve