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Re: [TLS] Comments on

Watson Ladd <watsonbladd@gmail.com> Tue, 18 February 2014 05:39 UTC

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From: Watson Ladd <watsonbladd@gmail.com>
To: Bill Frantz <frantz@pwpconsult.com>
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Cc: Adam Langley <agl@imperialviolet.org>, Niels Möller <nisse@lysator.liu.se>, "tls@ietf.org" <tls@ietf.org>
Subject: Re: [TLS] Comments on
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On Mon, Feb 17, 2014 at 9:19 PM, Bill Frantz <frantz@pwpconsult.com> wrote:
> On 2/17/14 at 9:00 PM, watsonbladd@gmail.com (Watson Ladd) wrote:
>
>> I don't think there is any way around that. If I want to ensure all
>> read data has property P, and P depends on every byte of input, I need
>> to look at all the input bytes before revealing any data.
>
>
> Well, you can work on sub-blocks of the whole chunk of data. Either a MAC or
> digital signature on each sub-block would do. Verify the sub-block and it
> can be released to the relying application. If we are using a 32 byte MAC,
> then 3200 byte blocks would only have 1% overhead for checking. There are
> very few systems where a buffer size the order of 3200 would cause a serious
> problem.
>

The application has to be ready to accept truncations on arbitrary
subblock boundaries for this to work out.
That's not the same as semantics indicating the entire file is fine if
you can read from it.
Sincerely,
Watson Ladd

> Cheers - Bill
>
> -----------------------------------------------------------------------
> Bill Frantz        |The nice thing about standards| Periwinkle
> (408)356-8506      |is there are so many to choose| 16345 Englewood Ave
> www.pwpconsult.com |from.   - Andrew Tanenbaum    | Los Gatos, CA 95032
>



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