Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site brl-tgr.ARPA Path: utzoo!watmath!clyde!burl!ulysses!allegra!bellcore!decvax!genrad!panda!talcott!harvard!seismo!brl-tgr!tgr!Craig.Everhart@CMU-CS-A.ARPA From: Craig.Everhart@CMU-CS-A.ARPA Newsgroups: net.mail.headers Subject: Re: Checksum as a replacement for missing Message-ID. Message-ID: <9080@brl-tgr.ARPA> Date: Fri, 8-Mar-85 12:08:58 EST Article-I.D.: brl-tgr.9080 Posted: Fri Mar 8 12:08:58 1985 Date-Received: Mon, 11-Mar-85 05:32:21 EST Sender: news@brl-tgr.ARPA Lines: 19 Why use the From: or Date: fields at all? The From: field is a popular candidate for editing by automatic agents; I'm not convinced that Mr. Palme's algorithm will remove all traces of that editing. The Date:-field algorithm was underspecified (year in century, as SMTP would have? What is the origin for months? Any use of time zone information?). For that matter, I'm not sure that all agents would agree on the concept of ``printing character'' in the body of the message. Why not use an algorithm based solely on the body of the message? It can ignore characters outside the range [33,126] (decimal, inclusive); obviously it would only count characters in that range when incrementing the checksum counter. It may be less expensive to use something other than multiplication as a basis for the checksum on many small machines. Are there suitable algorithms based on bit rotations or shifts? And perhaps the whole discussion should be moved into an RFC.