Re: [quicwg/base-drafts] Consider simplifying Packet Number Encryption (#1575)

David Schinazi <> Tue, 17 July 2018 18:41 UTC

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From: David Schinazi <>
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Subject: Re: [quicwg/base-drafts] Consider simplifying Packet Number Encryption (#1575)
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I agree that this isn't necessary - I'm just wondering if this proposal could make implementations simpler and safer.

Proposal: always encrypt four bytes [pn_offset, pn_offset + 3] and always have the sample start at pn_offset + 4. If the sample were to overflow the payload + tag (which only happens if you use 128-bit AES and have pn_len + payload_len < 4), you just pad the sample with zeroes. In the worst case scenario the sample contains two bytes of zero but you still have a 128bit secret key. Is that unacceptable?

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