From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from firstgate.proxmox.com (firstgate.proxmox.com [212.224.123.68]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.proxmox.com (Postfix) with ESMTPS id C9D89609A6 for ; Wed, 18 Nov 2020 07:47:44 +0100 (CET) Received: from firstgate.proxmox.com (localhost [127.0.0.1]) by firstgate.proxmox.com (Proxmox) with ESMTP id AE38B17BFD for ; Wed, 18 Nov 2020 07:47:14 +0100 (CET) Received: from proxmox-new.maurer-it.com (proxmox-new.maurer-it.com [212.186.127.180]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by firstgate.proxmox.com (Proxmox) with ESMTPS id 3E8F717BF2 for ; Wed, 18 Nov 2020 07:47:14 +0100 (CET) Received: from proxmox-new.maurer-it.com (localhost.localdomain [127.0.0.1]) by proxmox-new.maurer-it.com (Proxmox) with ESMTP id 09706438CD for ; Wed, 18 Nov 2020 07:47:14 +0100 (CET) To: Proxmox Backup Server development discussion , Dietmar Maurer , =?UTF-8?Q?Fabian_Gr=c3=bcnbichler?= References: <20201117175725.3634238-1-f.gruenbichler@proxmox.com> <1774426658.212.1605677252807@webmail.proxmox.com> <645547754.213.1605678469368@webmail.proxmox.com> From: Thomas Lamprecht Message-ID: <6447caa6-7079-4515-af39-4322fdd8a69f@proxmox.com> Date: Wed, 18 Nov 2020 07:47:13 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:83.0) Gecko/20100101 Thunderbird/83.0 MIME-Version: 1.0 In-Reply-To: <645547754.213.1605678469368@webmail.proxmox.com> Content-Type: text/plain; charset=UTF-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable X-SPAM-LEVEL: Spam detection results: 0 AWL -0.089 Adjusted score from AWL reputation of From: address KAM_DMARC_STATUS 0.01 Test Rule for DKIM or SPF Failure with Strict Alignment NICE_REPLY_A -0.001 Looks like a legit reply (A) RCVD_IN_DNSWL_MED -2.3 Sender listed at https://www.dnswl.org/, medium trust SPF_HELO_NONE 0.001 SPF: HELO does not publish an SPF Record SPF_PASS -0.001 SPF: sender matches SPF record Subject: Re: [pbs-devel] [PATCH proxmox-backup 0/7] add, persist and check key fingerprint X-BeenThere: pbs-devel@lists.proxmox.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: Proxmox Backup Server development discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 18 Nov 2020 06:47:44 -0000 On 18.11.20 06:47, Dietmar Maurer wrote: >> On 11/18/2020 6:27 AM Dietmar Maurer wrote: >> >> =20 >> Do we really need/want a 256bit long fingerprint? >> >> I thought 64bit (or maybe 32bit) would be large enough? >> If not, why does it have to be that large? >=20 > some quick math: >=20 > max keys a user generate in his live: 1024 (2=C2=B9=E2=81=B0) >=20 > so the likelihood of a 32bit fingerprint clash is=20 >=20 > W =3D 1/2^=C2=B2=C2=B2 (1/4Millions) >=20 > which is, unlikely, but possible. >=20 > But with 64bit it is extremely unlikely (1/2=E2=81=B5=E2=81=B4). =46rom a pure user experience I think it could be better to present 8 byt= e of fingerprint information - as the nerves/stress ratio is probably not to good at times= where this is required. 8 byte: "90:A1:CA:44:BE:0B:D4:1C" vs. 32 byte: "90:A1:CA:44:BE:0B:D4:1C:F7:D9:F5:2F:7C:92:DB:69:B2:2A:AF:6A:1C:= 7A:DB:0C:03:93:3E:EA:95:EC:26:92" I mean, after all, this is rather informal and even if there would be a u= nlikely collision it does not actually compromises security in any way I can thin= k of.