Path: csiph.com!x330-a1.tempe.blueboxinc.net!usenet.pasdenom.info!gegeweb.42!gegeweb.eu!nntpfeed.proxad.net!proxad.net!feeder1-1.proxad.net!198.186.194.247.MISMATCH!news-out.readnews.com!transit3.readnews.com!postnews.google.com!glegroupsg2000goo.googlegroups.com!not-for-mail From: Lew Newsgroups: comp.lang.java.programmer Subject: Re: Simple alphanumeric "encryption"? Date: Tue, 18 Oct 2011 08:43:00 -0700 (PDT) Organization: http://groups.google.com Lines: 28 Message-ID: <13972545.1242.1318952580309.JavaMail.geo-discussion-forums@prfk19> References: Reply-To: comp.lang.java.programmer@googlegroups.com NNTP-Posting-Host: 66.109.106.72 Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 X-Trace: posting.google.com 1318952759 18877 127.0.0.1 (18 Oct 2011 15:45:59 GMT) X-Complaints-To: groups-abuse@google.com NNTP-Posting-Date: Tue, 18 Oct 2011 15:45:59 +0000 (UTC) In-Reply-To: Complaints-To: groups-abuse@google.com Injection-Info: glegroupsg2000goo.googlegroups.com; posting-host=66.109.106.72; posting-account=CP-lKQoAAAAGtB5diOuGlDQk0jIwmH0T User-Agent: G2/1.0 X-Google-Web-Client: true Xref: x330-a1.tempe.blueboxinc.net comp.lang.java.programmer:8955 Qu0ll wrote: > "Tom Anderson" wrote: > > Sorry about the lack of indent... > > ------------------------------------------------------------------------------------------------ > Oddly, i have a paper called "Ciphers with Arbitrary Finite Domains" > sitting in my reading queue right not. > > You have at least two basic routes of attack here. > > First, recognise that alphanumerism is just an encoding of a general bit > string. Decode the alphanumeric string into a bit string (by taking it as > a base-36 or base-62 number, or whatever), encrypt that, then re-encode > it. BigInteger has a constructor which takes a string and a radix, and a > toString method which takes a radix. ... [snip] > ------------------------------------------------------------------------------------------------ > > OK, thanks Tom for that - the first option looks promising. > > I have 2 questions: > > Is there any significance in the choice of numbers 36 and 62? Of course. It's the number of digit symbols available. Using the standard 26-letter English alphabet and the numerals zero through nine, you have 36 symbols if you restrict to one case and 62 if you allow upper and lower case. -- Lew