Return-Path: X-Original-To: apmail-couchdb-dev-archive@www.apache.org Delivered-To: apmail-couchdb-dev-archive@www.apache.org Received: from mail.apache.org (hermes.apache.org [140.211.11.3]) by minotaur.apache.org (Postfix) with SMTP id E7857751D for ; Tue, 15 Nov 2011 07:58:48 +0000 (UTC) Received: (qmail 47006 invoked by uid 500); 15 Nov 2011 07:58:43 -0000 Delivered-To: apmail-couchdb-dev-archive@couchdb.apache.org Received: (qmail 46836 invoked by uid 500); 15 Nov 2011 07:58:40 -0000 Mailing-List: contact dev-help@couchdb.apache.org; run by ezmlm Precedence: bulk List-Help: List-Unsubscribe: List-Post: List-Id: Reply-To: dev@couchdb.apache.org Delivered-To: mailing list dev@couchdb.apache.org Received: (qmail 46821 invoked by uid 99); 15 Nov 2011 07:58:38 -0000 Received: from athena.apache.org (HELO athena.apache.org) (140.211.11.136) by apache.org (qpsmtpd/0.29) with ESMTP; Tue, 15 Nov 2011 07:58:38 +0000 X-ASF-Spam-Status: No, hits=-0.0 required=5.0 tests=RCVD_IN_DNSWL_LOW,SPF_NEUTRAL X-Spam-Check-By: apache.org Received-SPF: neutral (athena.apache.org: local policy) Received: from [209.85.213.52] (HELO mail-yw0-f52.google.com) (209.85.213.52) by apache.org (qpsmtpd/0.29) with ESMTP; Tue, 15 Nov 2011 07:58:32 +0000 Received: by ywb5 with SMTP id 5so8407830ywb.11 for ; Mon, 14 Nov 2011 23:58:11 -0800 (PST) Received: by 10.68.208.225 with SMTP id mh1mr58453951pbc.17.1321343890430; Mon, 14 Nov 2011 23:58:10 -0800 (PST) MIME-Version: 1.0 Received: by 10.143.91.10 with HTTP; Mon, 14 Nov 2011 23:57:49 -0800 (PST) In-Reply-To: References: From: Jason Smith Date: Tue, 15 Nov 2011 07:57:49 +0000 Message-ID: Subject: Re: Why MD5 is used for hashes, also about non-deterministic IDs. To: dev@couchdb.apache.org Content-Type: text/plain; charset=UTF-8 On Tue, Nov 15, 2011 at 7:34 AM, Alex Besogonov wrote: >>> Now I make a change to 'Doc' at machine A. This creates a new revid >>> with new md5 hash. >>> A malicious software somehow learns about this update and creates >>> another document >>> on machine B, contriving it so to make the resulting hash to be the >>> same as on machine A. >> Before going any further, you must show why we care about the contents >> of machine B. >> Why would I log in to machine B if I do not trust B's owner? Why would >> I clone your Git repository if I do not know you? > The problem is, MD5 hash depends on _untrusted_ data that external > processes might put into the database. > > For example, imagine that machines A and B use CouchDB to store > certificates. I ask again. -- Iris Couch