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Re: [TLS] TLS1.3

mrex@sap.com (Martin Rex) Mon, 11 February 2013 15:33 UTC

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Subject: Re: [TLS] TLS1.3
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Martin Rex wrote:
> > 
> > >When the encryption scheme that is used is bijective, then it will not matter
> > >(to the confidentiality of the encryption) whether AtE or EtA is used, as
> > >long as authentication covers the exact same information in both cases, i.e.
> > >*ALL* of it, padding included.
> > 
> > However you do need to to MAC the IV.
> 
> Correct. 

Re-thinking it,  I believe it would be OK to _not_ cover the CBC-IV
in the AtE, while you *MUST* cover the IV in the EtA case.

The reason being that the IV does not impact the bijectivity of the cipher,
and is not part of the plaintext.

-Martin

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