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Re: [TLS] Comments on

Dr Stephen Henson <lists@drh-consultancy.co.uk> Fri, 14 February 2014 15:06 UTC

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From: Dr Stephen Henson <lists@drh-consultancy.co.uk>
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On 14/02/2014 08:42, Niels Möller wrote:
> Adam Langley <agl@google.com> writes:
> 
>> (The lengths were originally prefixes of the data. wtc suggested
>> moving them to the end so that the AEAD could be computed without
>> knowing the length of the data apriori. Although this does lead to the
>> possibility of "streaming" APIs which I would discourage as they
>> release unauthenticated plaintext and force others to also.)
> 
> I agree that most applications shouldn't use streaming operation, at
> least for decryption. But I also think there are valid usecases for
> streaming operation, e.g., processing a large file where you really want
> a single indication of autenticity for the complete file. In GNU Nettle,
> which is a general purpose but pretty low level crypto library, I'd like
> to support aead streaming operation whenever possible.
> 

Though not relevant to TLS there are also use cases where the whole length of
the data is not known is advance. A couple of examples would be reading from a
pipe or where the stream is obtained from an ASN1 BER decoder (CMS for example).

Steve.
-- 
Dr Stephen N. Henson.
Core developer of the   OpenSSL project: http://www.openssl.org/
Freelance consultant see: http://www.drh-consultancy.co.uk/
Email: shenson@drh-consultancy.co.uk, PGP key: via homepage.

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