Re: [TLS] Comments on

On Mon, Feb 17, 2014 at 12:09 AM, Nikos Mavrogiannopoulos
<nmav@redhat.com> wrote:
> On Fri, 2014-02-14 at 14:49 -0500, Adam Langley wrote:
>
>> > By streaming, I don't advocate you do the decryption in a pipe line;
>> > that's clearly a dangerous habit. Usecase is more like on one machine
>> > running
>> >   src-machine$ tar -cf - foo-dir | aead-encrypt | send
>> This use of streaming is fine by my criteria, assuming that
>> "aead-encrypt" is chunking the input into different blocks and
>> applying the AEAD to each block. This is perfectly fine with a
>> one-shot(*), AEAD API at the core.
>
> I'd pretty much agree with the chunked approach, but I now realize that
> it is more hard to get it right than the streaming one. In the chunked
> approach one would need to implement sequence numbers (could be implicit
> as additional data) and a termination block. So both approaches have
> quite some disadvantages. The streaming approach allows for misuse of
> the API which may cancel the benefits of AEAD, and the chunked approach
> requires the developer to create a safe protocol over AEAD.
>
> If the idea is for AEAD to be used by an average developer, it seems we
> need even a higher abstraction than that; even for such a simple
> use-cases.

Let's back up a bit. The assumption is that we are sending a file over
the network, and we want to encrypt and authenticate it. If we have an
encrypted and authenticated channel all is good. Alternatively, we can
encrypt the entire file as one big chunk and decrypt on receipt.  I've
still not found a case where one of these doesn't work.

Sincerely,
Watson Ladd
>
> regards,
> Nikos
>
>
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