At 01:30 +0100 on 10/17/2013, Richard Clayton wrote about Re:
[ietf-smtp] DKIM encryption, was Request for discussion:
>erk ... you don't generally wish to use public keys on whole messages,
>the planet is getting pretty warm already -- there are practical reasons
>why existing schemes involve encrypting with a stream cipher with a
>randomly chosen session key and then just using the public key system
>for transmitting the session key.
How about doing the message encryption with the stream cipher and use
the public key to encrypt it as a separate MIME part (ie: The message
is multi-part with the key MIME part and the encrypted MIME part)?
multipart/encrypted, in other words. See RFC 1847.
And if we're going to consider various security building blocks, how
about identity-based encyption? It could be used here to extend this
to a full end-to-end mechanism without having to put keys for every address
in the DNS.
OTOH, IBE is probably patented to the hilt. So maybe not.
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