Re: [quicwg/base-drafts] Encrypting Retry token (#3274)

Martin Thomson <notifications@github.com> Wed, 27 November 2019 23:26 UTC

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Subject: Re: [quicwg/base-drafts] Encrypting Retry token (#3274)
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Since I did this, I've realized that even this was an overly pessimistic outcome.  By precomputing the XOR stream for CTR protection, it should be possible to make an even faster version of the protected form here.

The result should be to narrow the gap between the GHASH-only and encrypted variant further.  The difference should be limited to performing an XOR with a fixed value and a single AES operation (which in my experience is marginally cheaper than an extra GHASH operation, though the addition of ODCID to the AAD is rarely a full block, so it's hard to predict the exact outcome).

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