Return-Path: X-Original-To: quic-issues@ietfa.amsl.com Delivered-To: quic-issues@ietfa.amsl.com Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 286E73A0ADA for ; Thu, 7 May 2020 18:37:12 -0700 (PDT) X-Virus-Scanned: amavisd-new at amsl.com X-Spam-Flag: NO X-Spam-Score: -3.096 X-Spam-Level: X-Spam-Status: No, score=-3.096 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, HTML_IMAGE_ONLY_32=0.001, HTML_MESSAGE=0.001, MAILING_LIST_MULTI=-1, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001] autolearn=ham autolearn_force=no Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (1024-bit key) header.d=github.com Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id oMRyLNHyxUL0 for ; Thu, 7 May 2020 18:37:10 -0700 (PDT) Received: from out-27.smtp.github.com (out-27.smtp.github.com [192.30.252.210]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id B82BC3A0AD7 for ; Thu, 7 May 2020 18:37:10 -0700 (PDT) Received: from github-lowworker-f62aa54.va3-iad.github.net (github-lowworker-f62aa54.va3-iad.github.net [10.48.17.68]) by smtp.github.com (Postfix) with ESMTP id E1DFDE0DBE for ; Thu, 7 May 2020 18:37:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=github.com; s=pf2014; t=1588901829; bh=ZepofQ0gpQlNgqem/p7bm5TEkJuoI/APj6ZvnUJ3+2A=; h=Date:From:Reply-To:To:Cc:In-Reply-To:References:Subject:List-ID: List-Archive:List-Post:List-Unsubscribe:From; b=OuW0mFEE5x0USSWRhNxVhxZC9zQvl9yGofvHXj+714MBdymQT36/R5Y4IPJLyRcdF OGJq6OKk4iYdbkKv3c7K0jyaiTils5Y0sAh85pXeetEocxhzjbRxvZuUop3cckN6vq ZpLCqSFqFEt4GXaZ1F1lfaArJ/z54M19rKDzIj+Y= Date: Thu, 07 May 2020 18:37:09 -0700 From: Martin Thomson Reply-To: quicwg/base-drafts To: quicwg/base-drafts Cc: Subscribed Message-ID: In-Reply-To: References: Subject: Re: [quicwg/base-drafts] Forgery limits on packet protection (#3619) Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="--==_mimepart_5eb4b7c5d05f4_74e33fb8958cd95c828fc"; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: list X-GitHub-Sender: martinthomson X-GitHub-Recipient: quic-issues X-GitHub-Reason: subscribed X-Auto-Response-Suppress: All X-GitHub-Recipient-Address: quic-issues@ietf.org Archived-At: X-BeenThere: quic-issues@ietf.org X-Mailman-Version: 2.1.29 List-Id: Notification list for GitHub issues related to the QUIC WG List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 08 May 2020 01:37:12 -0000 ----==_mimepart_5eb4b7c5d05f4_74e33fb8958cd95c828fc Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit @chris-wood points out an error in my calculation. I had based my calculations on direct mapping of `l[E]` in the CCM analysis to `l` in our calculations. That is, `l` was the number of blocks in the message. But the analysis by Jonsson defines this as: ![image](https://user-images.githubusercontent.com/67641/81360611-b252b580-911f-11ea-8d81-d6824c685d51.png) The definition of \Beta is the CCM function, so this function really reduces to 2 times the length of the message (in blocks), plus 1 (to account for the additional encryption). We can ignore the extra 1 as that is absorbed by the tag length. I'm updating the numbers in the PR. The result is another halving of the number of packets. @fxguenther, @ad-l, it's pretty clear that I'm out of my depth here, so your input would be highly valued. -- You are receiving this because you are subscribed to this thread. Reply to this email directly or view it on GitHub: https://github.com/quicwg/base-drafts/issues/3619#issuecomment-625581184 ----==_mimepart_5eb4b7c5d05f4_74e33fb8958cd95c828fc Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: 7bit

@chris-wood points out an error in my calculation. I had based my calculations on direct mapping of l[E] in the CCM analysis to l in our calculations. That is, l was the number of blocks in the message. But the analysis by Jonsson defines this as:

image

The definition of \Beta is the CCM function, so this function really reduces to 2 times the length of the message (in blocks), plus 1 (to account for the additional encryption). We can ignore the extra 1 as that is absorbed by the tag length.

I'm updating the numbers in the PR. The result is another halving of the number of packets. @fxguenther, @ad-l, it's pretty clear that I'm out of my depth here, so your input would be highly valued.

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