From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,FREEMAIL_FROM autolearn=unavailable autolearn_force=no version=3.4.4 X-Received: by 10.31.14.10 with SMTP id 10mr22183346vko.27.1494185543355; Sun, 07 May 2017 12:32:23 -0700 (PDT) X-Received: by 10.157.39.138 with SMTP id c10mr1053371otb.9.1494185543302; Sun, 07 May 2017 12:32:23 -0700 (PDT) Path: eternal-september.org!reader01.eternal-september.org!reader02.eternal-september.org!news.eternal-september.org!news.eternal-september.org!feeder.eternal-september.org!border1.nntp.ams1.giganews.com!newsfeed.xs4all.nl!newsfeed9.news.xs4all.nl!newspeer1.nac.net!border2.nntp.dca1.giganews.com!nntp.giganews.com!t26no249808qtg.1!news-out.google.com!v18ni1179ita.0!nntp.google.com!c26no1255691itd.0!postnews.google.com!glegroupsg2000goo.googlegroups.com!not-for-mail Newsgroups: comp.lang.ada Date: Sun, 7 May 2017 12:32:22 -0700 (PDT) In-Reply-To: <99a9a77c-ebde-424c-a62d-8ced7e4090b6@googlegroups.com> Complaints-To: groups-abuse@google.com Injection-Info: glegroupsg2000goo.googlegroups.com; posting-host=2601:191:8303:2100:5985:2c17:9409:aa9c; posting-account=fdRd8woAAADTIlxCu9FgvDrUK4wPzvy3 NNTP-Posting-Host: 2601:191:8303:2100:5985:2c17:9409:aa9c References: <7edc0e62-80fe-4a91-9015-69c781207fc8@googlegroups.com> <99a9a77c-ebde-424c-a62d-8ced7e4090b6@googlegroups.com> User-Agent: G2/1.0 MIME-Version: 1.0 Message-ID: Subject: Re: Tasking and Concurrent Programming Using Multiple Ada Programs. From: Robert Eachus Injection-Date: Sun, 07 May 2017 19:32:23 +0000 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Original-Bytes: 3110 Xref: news.eternal-september.org comp.lang.ada:46693 Date: 2017-05-07T12:32:22-07:00 List-Id: On Saturday, April 29, 2017 at 12:08:57 PM UTC-4, Austin Obyrne wrote: > I have come over from sci crypt group to ask your advice on an > encryption concept... Sigh! See if you can get a copy of The Codebreakers by David Kahn from you= r library. It was initially published in the 1960s, and there is a revised= edition from 1997 that I haven't seen. Of course, just about anything I = did during my career is covered in one added chapter. There are other books= I could recommend as introductions to cryptography, but none covering mate= rial more recent than WWII. Modern cryptography, including public-key cryp= tography and FIPS standard algorithms are all very math intensive, mostly N= umber Theory. The system you are attempting sounds like a variation on polyalphabetic sub= stitution. The US Government kept the "index of coincidence" a secret duri= ng WWII, and that was the major weakness of polyalphabetic systems. Once y= ou find the IC, you can solve the system as n more standard systems. Most = of the FIPS systems, such as AES, uses the previous state of the system as = part of the key for the next (256) bits. Oh, and don't try to implement AES in Ada, without some particular need. I= t can be done, but most CPU chips today already have AES support built-in. Rule one of cryptography: security by obscurity does not work. If the syst= em is not secure if your opponent knows how it works, it is not secure. Ru= le two is that there is no point to making a system more secure than "pract= ical cryptography," such as breaking and entering. During WWII there were = several naval engagements as part of practical cryptography to grab Naval E= nigma machines and codebooks.