Return-Path: X-Original-To: cfrg@ietfa.amsl.com Delivered-To: cfrg@ietfa.amsl.com Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 0822E3A26E3 for ; Tue, 31 Mar 2020 11:55:45 -0700 (PDT) X-Virus-Scanned: amavisd-new at amsl.com X-Spam-Flag: NO X-Spam-Score: 0.974 X-Spam-Level: X-Spam-Status: No, score=0.974 tagged_above=-999 required=5 tests=[SPF_HELO_NONE=0.001, SPF_SOFTFAIL=0.972, URIBL_BLOCKED=0.001] autolearn=no autolearn_force=no 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 8eMc5jkxczpg for ; Tue, 31 Mar 2020 11:55:43 -0700 (PDT) Received: from mailout.easymail.ca (mailout.easymail.ca [64.68.200.34]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 7B2123A26DF for ; Tue, 31 Mar 2020 11:55:43 -0700 (PDT) Received: from localhost (localhost [127.0.0.1]) by mailout.easymail.ca (Postfix) with ESMTP id A81CBBF9C5; Tue, 31 Mar 2020 18:55:42 +0000 (UTC) X-Virus-Scanned: Debian amavisd-new at emo04-pco.easydns.vpn Received: from mailout.easymail.ca ([127.0.0.1]) by localhost (emo04-pco.easydns.vpn [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id JpgZSZCbHJu5; Tue, 31 Mar 2020 18:55:42 +0000 (UTC) Received: from [192.168.3.179] (66-215-86-135.dhcp.psdn.ca.charter.com [66.215.86.135]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mailout.easymail.ca (Postfix) with ESMTPSA id 6F1ADBF972; Tue, 31 Mar 2020 18:55:39 +0000 (UTC) Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Mime-Version: 1.0 (1.0) From: Henry B Hotz In-Reply-To: <83571efb-a32f-6a59-a496-de56716f07da@htt-consult.com> Date: Tue, 31 Mar 2020 11:55:37 -0700 Cc: cfrg@ietf.org Message-Id: References: <83571efb-a32f-6a59-a496-de56716f07da@htt-consult.com> To: Robert Moskowitz X-Mailer: iPhone Mail (17C54) Archived-At: Subject: Re: [Cfrg] Encrypt in place guidance X-BeenThere: cfrg@irtf.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Crypto Forum Research Group List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 31 Mar 2020 18:55:45 -0000 What about format preserving encryption? Personal email. hbhotz@oxy.edu > On Mar 31, 2020, at 11:30 AM, Robert Moskowitz w= rote: >=20 > =EF=BB=BFThe problem is in the Unmanned Aircraft broadcast messages (see D= RIP work). >=20 > In the System Message defined in ASTM F3411-19 there are 8 bytes of sensit= ive Operator Information that I want to encrypt. I can get a shared secret v= ia the PK mechanism in ECIES. >=20 > The challenge is in encrypting, then decrypting these 8 bytes. >=20 > There is no room for expansion in the message. All we have are these 8 by= tes. >=20 > There is nothing unique in each System Message to use an an IV. There are 7= bytes of mission information and 1 byte of flags that are constant for a gi= ven mission (but may be the same in a later mission). >=20 > There are 8 reserved bytes, but I feel they left out 4 bytes of important O= perator Information (thus making 12 bytes to encrypt). So no grabbing those r= eserved bytes. >=20 > Since this information is of limited value for some period after the compl= etion of the mission, I was considering just using AES-ECB. >=20 > Opps. I need 16 bytes for the output of AES-ECB. Or at least that is my= reading of the ECB mode. >=20 > So I am seeking guidance here on what cipher to use in this particular sit= uation. >=20 > Thank you. >=20 >=20 > _______________________________________________ > Cfrg mailing list > Cfrg@irtf.org > https://www.irtf.org/mailman/listinfo/cfrg