RE: digested-data, surreptitious forwarding, D-H
Trevor Perrin <Tperrin@sigaba.com> Sat, 27 July 2002 02:42 UTC
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From: Trevor Perrin <Tperrin@sigaba.com>
To: Trevor Perrin <Tperrin@sigaba.com>, "'ietf-smime@imc.org'" <ietf-smime@imc.org>
Subject: RE: digested-data, surreptitious forwarding, D-H
Date: Fri, 26 Jul 2002 19:28:32 -0700
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scratch question 3, this week has fried my brains more than I thought.. > -----Original Message----- > From: Trevor Perrin [mailto:Tperrin@sigaba.com] > Sent: Friday, July 26, 2002 2:32 PM > To: 'ietf-smime@imc.org' > Subject: digested-data, surreptitious forwarding, D-H > > > > > With more diligence I probably could've answered these from > the archives. > But a few questions: > > 1) I'm surprised S/MIME doesn't use CMSs' digested-data with > enveloped-data. > In the case of encrypted but not signed mails, doesn't this leave the > message vulnerable to things like cut-and-paste attacks > (where an attacker > reorders ciphertext blocks, so upon decrypting the recipient > sees reordered > plaintext)? > > 2) At some point I thought there was an Internet-Draft for a signed > attribute to address Don Davis' surreptitious forwarding > concern. I don't > see it now. Has that been dropped, or has some other fix > been incorporated > somewhere? > > 3) I see that Diffie-Hellman key pairs can be encrypted to, > using either > static-static or ephemeral-static modes. It seems like a > Diffie-Hellman key > pair should be able to sign as well, using something like a > static-ephemeral > mode. Is there a cryptographic reason why this > can't/shouldn't be done, or > is it just incidental that it isn't supported? > > The reason it seems like this might be useful is that Diffie-Hellman > agreement values can be cached, so a signer could perform > lots of signatures > efficiently with such a key pair, which could be useful for > something like a > DOMSEC gateway, which may have high volume mail flows and > large key pairs. > > Trevor >
- digested-data, surreptitious forwarding, D-H Trevor Perrin
- RE: digested-data, surreptitious forwarding, D-H Trevor Perrin
- Re: digested-data, surreptitious forwarding, D-H Peter Gutmann
- RE: digested-data, surreptitious forwarding, D-H Trevor Perrin
- RE: digested-data, surreptitious forwarding, D-H Trevor Perrin
- RE: digested-data, surreptitious forwarding, D-H Peter Gutmann
- RE: digested-data, surreptitious forwarding, D-H Peter Gutmann