Re: [quicwg/base-drafts] First octet changes (#2006)

David Schinazi <notifications@github.com> Thu, 15 November 2018 22:18 UTC

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Subject: Re: [quicwg/base-drafts] First octet changes (#2006)
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DavidSchinazi commented on this pull request.



> +with the remaining bytes.
+
+{{pseudo-hp}} shows a sample algorithm for applying header protection. Removing
+protection only differs in the order in which the packet number length
+(pn_length) is determined.
+
+~~~
+mask = header_protection(hp_key, sample)
+
+pn_length = (packet[0] & 0x03) + 1
+if packet[0] & 0x80 == 0x80:
+   # Long header: 4 bits masked
+   packet[0] ^= mask[0] & 0x0f
+else:
+   # Short header: 5 bits masked
+   packet[0] ^= mask[0] & 0x1f

@marten-seemann you can grease this bit without encrypting it - just send a different random value with every packet. I would prefer to keep the spec simpler by never encrypting this bit.

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