[OLPC Security] [Techteam] Crypto export and python-crypto
C. Scott Ananian
cscott at laptop.org
Tue Jun 3 10:41:40 EDT 2008
On Tue, Jun 3, 2008 at 9:30 AM, Jameson Chema Quinn
<jquinn at cs.oberlin.edu> wrote:
> On formats, I agree in principle. But as your own email points out, there
> are already two different signature formats invented for the XO, because of
> specifics about what is to be signed. If these do not work for my needs, I
> do not see why I should not invent another.
Exactly because we already have two, we should avoid having *three*!
It would be better to patch one of these so we only have *one*. (And
what are the two formats you are referring to?)
> The OpenPGP attack you mention has to do with encryption, not signatures.
Please read page 25 of
there is (yet) no practical attack, it (like MD5) is not recommended
for new applications.
> I did look at JAR files, and decided that their format lacked some desirable
> features. They are based on md5 hashes, which are close to broken; they do
You are wrong. http://java.sun.com/j2se/1.3/docs/guide/jar/jar.html#Digital%20Signatures
> not allow for granting privileges to secondary keys, which means that
You can have any number of .SF signature files, signing any
combination of the contents.
> user; they interact poorly with differential versioning storage; and they do
They in fact interact quite well. See
> not allow for unsigned content in a signed bundle, which makes localization
I do not believe this to be the case.
> more of a pain. Any one of those problems I could have lived with, the three
> together seem to me like a good enough reason for changing a format. And
And in the absence of any of the three?
> The contents manifest specification does not fit my needs either.
I'll let this pass, for now, but I explicitly designed it to fit both
the OS and activity update case, so I find this statement puzzling. I
think what you mean is, "it does not solve *all* my problems for me",
and this is because it is not designed to. It is just one part of a
solution. But I prefer the JAR file format for activities anyway, so
I don't think it's worth belaboring this.
( http://cscott.net/ )
More information about the Security