<html><head><style> body {height: 100%; color:#000000; font-size:12pt; font-family:Times New Roman;}</style></head><body>You would want it to be reversible...the intent isn't to secure the URL, it's to shorten the URL. You would want anyone to be able to "de-shorten" the URL to compare it against blacklists, etc. And of course you want the browser to be able to de-shorten it.<br><br>The problem with the URL shortener is that it has to be something that anyone can use to decode any URL, anywhere. Requiring access to a database prevents that.<br><br>How about something like Base64, but which converts the string into a 12-character encoded string? For example, take the URL<br>http://www.ameslug.org/node/1<br><br>Using Base64 you get "aHR0cDovL3d3dy5hbWVzbHVnLm9yZy9ub2RlLzE=", which is not an improvement. But if you got instead "aHR0cDovL3d3", that would be much more manageable (if only it would decode back to the original URL string).<br><br>----- Original Message -----<br>From: Josh More <morej@alliancetechnologies.net><br>To: Central Iowa Linux Users Group <cialug@cialug.org><br>Sent: Thu, 15 Jul 2010 14:42:43 -0500 (CDT)<br>Subject: Re: [Cialug] TinyURL<br><br><div style="direction: ltr; font-family: Tahoma; color: #000000; font-size: 10px;"><div>Making proper hashing algorithms is actually really hard to do. You have to worry about collisions and reversing (in most cases).<br><br><br>For URL shorteners, it's often more efficient to implement an incrementer and just keep a database around.<br></div><div><br><div style="font-family: Tahoma; font-size: 13px;"><div style="font-family: Tahoma; font-size: 13px;"><div style="font-family: Tahoma; font-size: 13px;"><font style="font-family: Courier New;" color="#888888" size="1">-Josh More, CISSP, GIAC-GSLC, GIAC-GCIH, RHCE, NCLP<br><a href="mailto:morej@alliancetechnologies.net" target="_blank"><span class="il">morej@alliancetechnologies.net</span></a><br><br>515-245-7701 </font><div style="font-family: Tahoma; font-size: 13px;"></div></div></div></div></div><div style="font-family: Times New Roman; color: #000000; font-size: 16px;"><hr><div style="direction: ltr;" id="divRpF102749"><span color="#000000" style="font-family: Tahoma" size="2;"><strong>From:</strong> cialug-bounces@cialug.org [cialug-bounces@cialug.org] on behalf of j.bengtson@mchsi.com [j.bengtson@mchsi.com]<br><strong>Sent:</strong> Thursday, July 15, 2010 14:41<br><strong>To:</strong> Central Iowa Linux Users Group<br><strong>Subject:</strong> Re: [Cialug] TinyURL<br></span><br></div><div></div><div>I wonder why no one has made a way to take any URL and automatically shorten it. Consider an MD5 hash...you can take virtually any text, no matter how long, and the MD5 algorithm will return a 32-digit hex number. How hard is it to make something similar,<br> that can take a URL of any length and return an 8-character string that can then be decoded back to the original URL? Make that algorithm public open-source, and you've got a tinyURL mechanism that isn't dependent upon any vendor, can be checked against a<br> blacklist, and yet is short enough for mere humans to handle.<br><br><br>----- Original Message -----<br><br>From: Adam Shannon <br><br>To: Central Iowa Linux Users Group <br><br>Sent: Fri, 18 Jun 2010 22:54:01 -0500 (CDT)<br><br>Subject: Re: [Cialug] TinyURL<br><br><br>Having a service (or services) to shorten a url that breaks in use<br><br>(email, webpages...) is perfectly fine, but that service should only<br><br>be giving the user the actual link, not directing them to the link<br><br>they wanted.<br><br><br>What happens when that short link provider goes out of business or is<br><br>hacked, then I lose the ability to control where I will end up<br><br>(negating anything on the link I'm trying to reach does) because I<br><br>can't see where I'm going. If the service is hacked and spreads<br><br>malware than anyone with javascript or cookies allowed on that domain<br><br>will be infected or tracked.<br><br><br>In my view, short url providers should only be presenting a page for<br><br>the user as to what the short link represents, the short link is not<br><br>the same link and therefore shouldn't act the same. It's a<br><br>representation for another url.<br><br><br>Thoughts?<br><br><br>On Fri, Jun 18, 2010 at 17:26, Scott Prader wrote:<br><br>> Sometimes a URL that takes up multiple lines can get cut off with a carriage<br><br>> return inserted by some program, at some point. When I see a link, I like<br><br>> to think that I can click on it and not get a 404. TinyURL fixed this.<br><br>> What they don't do is auto-forward a 404 to archive.org, which tends to<br><br>> cover what a downed URL can't, whether it's complete or not.<br><br>><br><br>> -Scott<br><br>><br><br>> On Fri, Jun 18, 2010 at 4:58 PM, Barry Von Ahsen wrote:<br><br>>><br><br>>> 7 ff addons tagged 'unshort url', probably more under other tags<br><br>>><br><br>>> https://addons.mozilla.org/en-US/firefox/tag/unshort%20url<br><br>>><br><br>>> -barry<br><br>>><br><br>>><br><br>>><br><br>>> Nathan C. Smith wrote:<br><br>>> > Seems to me there could be a whole industry for a technology for<br><br>>> > converting the various short-URLs back to long ones, particularly if the<br><br>>> > tools and technology provide a means to mitigate potential risks.<br><br>>> ><br><br>>> > Don't bit.ly and others use a hash that stays the same for each<br><br>>> > shortening of a reference? So that if you shorten cialug.org and send it to<br><br>>> > me I will get the same shortened url if I do it?<br><br>>> ><br><br>>> > -Nate<br><br>>> ><br><br>>> >> -----Original Message-----<br><br>>> >> From: cialug-bounces@cialug.org<br><br>>> >> [mailto:cialug-bounces@cialug.org] On Behalf Of Ed Meacham (@work)<br><br>>> >> Sent: Friday, June 18, 2010 3:12 PM<br><br>>> >> To: 'Central Iowa Linux Users Group'<br><br>>> >> Subject: Re: [Cialug] TinyURL<br><br>>> >><br><br>>> >> I love the idea of URL shortening services. Though, they<br><br>>> >> definitely have instances where the use of one is more<br><br>>> >> appropriate than others... I don't see the need to shorten a<br><br>>> >> URL in an email, unless you're spreading "infectious-love."<br><br>>> >><br><br>>> >> Rather than write off TinyURL/Bit.ly, I would blame improper<br><br>>> >> organization and/or the sender not qualifying the details of<br><br>>> >> the URL in the message.<br><br>>> >><br><br>>> >> I see there is a plug-in for Thunderbird for converting a URL<br><br>>> >> into a TinyURL... wonder if it has a reversal option? (I<br><br>>> >> don't have Thunderbird installed on this machine to check) If<br><br>>> >> not, a lookup plug-in might be a good project for someone. :P<br><br>>> >><br><br>>> >> -emeacham (@work)<br><br>>> >><br><br>>> >> -----Original Message-----<br><br>>> >> From: cialug-bounces@cialug.org<br><br>>> >> [mailto:cialug-bounces@cialug.org] On Behalf Of Todd Walton<br><br>>> >> Sent: Friday, June 18, 2010 6:27 AM<br><br>>> >> To: Central Iowa Linux Users Group<br><br>>> >> Subject: [Cialug] TinyURL<br><br>>> >><br><br>>> >> And another reason I hate this tinyurl thing... I know<br><br>>><br><br>>><br><br>>> _______________________________________________<br><br>>> Cialug mailing list<br><br>>> Cialug@cialug.org<br><br>>> http://cialug.org/mailman/listinfo/cialug<br><br>><br><br>><br><br>> _______________________________________________<br><br>> Cialug mailing list<br><br>> Cialug@cialug.org<br><br>> http://cialug.org/mailman/listinfo/cialug<br><br>><br><br>><br><br><br><br><br>-- <br><br>Adam Shannon<br><br>Web Developer<br><br>http://ashannon.us<br><br>_______________________________________________<br><br>Cialug mailing list<br><br>Cialug@cialug.org<br><br>http://cialug.org/mailman/listinfo/cialug<br><br></div></div></div><br><br></cialug@cialug.org></morej@alliancetechnologies.net></body></html>