From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from v1.tansi.org (mail.tansi.org [84.19.178.47]) by mail.server123.net (Postfix) with ESMTP for ; Tue, 31 Mar 2020 08:43:39 +0200 (CEST) Received: from gatewagner.dyndns.org (81-6-44-245.init7.net [81.6.44.245]) by v1.tansi.org (Postfix) with ESMTPA id 808F114014C for ; Tue, 31 Mar 2020 08:43:38 +0200 (CEST) Date: Tue, 31 Mar 2020 08:43:39 +0200 From: Arno Wagner Message-ID: <20200331064338.GA4895@tansi.org> References: <566872408.1293730.1585598590645.ref@mail.yahoo.com> <566872408.1293730.1585598590645@mail.yahoo.com> <20200330210022.GA31903@tansi.org> <1807406216.1448262.1585603129820@mail.yahoo.com> <20200331014306.GA2009@tansi.org> <672718044.1618732.1585632916735@mail.yahoo.com> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Disposition: inline Content-Transfer-Encoding: quoted-printable In-Reply-To: <672718044.1618732.1585632916735@mail.yahoo.com> Subject: Re: [dm-crypt] bits vs bytes List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: dm-crypt@saout.de On Tue, Mar 31, 2020 at 07:35:16 CEST, JT Mor=E9e wrote: >=20 > On Monday, March 30, 2020, 6:43:11 PM MST, Arno Wagner = wrote:=20 > > Not in a cryptographic context. You could also want to etch them >=20 > is that because the 512 bits is not the size of the key but instead a > measurement of one component that goes into generating the key? Well, block-ciphers have gotten to respect CPU operations recently,=20 so they are starting to use bytes internally ti increase efficiency.=20 But look at classic DES, and every but pretty much gets treated by=20 itself or bits get grpuped in ways that have nothing to do with byte boundaries. Or look at RSA and whether you have a 4096 bit, 4095 bit=20 or 4097 bit modulus makes no difference. Of course you usually go for multiples of 8, but that is just to accomodate a specific implementation (computers with 8 bit bytes), not anything that is part of the algebra of the cipher. Just accept it, it makes sense form a mathematical viewpoint. Otherwise you would need to multiply by 8 in a lot of places. And you could also use nibbles (4 bit) words (16 bits),=20 long words (32 bits) or quadwords (64 bits) as "units". The=20 byte is not really specuial. Regards, Arno --=20 Arno Wagner, Dr. sc. techn., Dipl. Inform., Email: arno@wagner.name GnuPG: ID: CB5D9718 FP: 12D6 C03B 1B30 33BB 13CF B774 E35C 5FA1 CB5D 9718 ---- A good decision is based on knowledge and not on numbers. -- Plato If it's in the news, don't worry about it. The very definition of=20 "news" is "something that hardly ever happens." -- Bruce Schneier