un-trusting MD5 in gpg
dshaw at jabberwocky.com
Thu May 7 17:34:22 CEST 2009
On May 7, 2009, at 4:57 AM, Werner Koch wrote:
> On Thu, 7 May 2009 00:04, dshaw at jabberwocky.com said:
>> Blacklist is pretty good. We could call it "blacklist-
>> digests" (which
>> gives us a name for "blacklist-ciphers" later). It's reasonably
>> just from the name.
> I agree. That term is different from disabled and may be used with
> different semantics in other tools.
> I would prefer
> --blacklist-digest-algo NAME_or_NUMBER
> The reason is that we do not need a specific order as with
> personal-digest-preferences. It makes implementation (cf. gpgconf)
> easier and better matches other options related to algorithms.
Sounds good to me. So, thus far, the plan sounds like:
--blacklist-digest-algo (name or number)
--no-blacklist-digest-algo (name or number)
Repeating the blacklist-digest-algo option can be done to add more
than one algorithm to the blacklist. no-blacklist-digest-algo can be
used to remove something from the list. Whoever gets in last (add to
the list or remove from the list) wins.
A blacklisted digest will cause signature verification to fail with an
appropriate error message along the lines of "digest algorithm is
blacklisted" (internally, GPG_ERR_BLACKLISTED_DIGEST or the like).
A key certification created with a blacklisted digest will not be part
of the web of trust.
A blacklisted digest will also not be usable when creating a signature/
certification, with the same sort of error returned.
This does not affect the use of the digest in things like --print-md.
gpg --version will flag blacklisted algorithms by putting them in
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