I had this issue with MD5 hashes recently, but with even more constraints!

First, on top of using the MD5 hash in a URL, and sending that URL in an email, I also needed to use the MD5 hash in an actual email address. (Thus allowing the recipient to either go to the URL or reply to the email address.) Second, I couldn't translate to a period within the MD5 hash, because that character was already being used for something else.

I ended up using this translation (the translation from plus to plus is intentional): tr,+=/,+-_, That works fine for the email address. The only iffy part is the plus in the URL; I just made sure that the CGI script doesn't convert the plus to a space.

In reply to Re: Re: (tye)Re: Compact MD5 representation by chipmunk
in thread Compact MD5 representation by jplindstrom

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