evince - coordinate verification

Why do you log IP addresses?: IP address logging is one of several tools used to prevent unscrupulous individuals from using an automated brute-force attack in order to derive cache coordinates. When you've made an incorrect attempt, you will need to wait 10 minutes before trying again. If you make too many incorrect attempts within a specific time-frame, any more attempts from that IP address are blocked. The blocking is released after a suitable time period has elapsed. IP address records are periodically cleared from the system. IP addresses are only logged when incorrect coordinates are entered. But entering correct coordinates will not clear previous incorrect attempts. Only time will do that.
What's the "Validation Code" and why do I have to enter it?: Like IP address logging, this is another tool to prevent individuals from abusing the site. The validation code (called a captcha) is a method to attempt to ensure that it is a human being, not an automated program, that is making the request. If the validation code is entered incorrectly, no coordinate validation will take place, so it doesn't count as an incorrect try.
Why can't I see the see the validation code image, and how do I fix it?: Most likely, your browser or firewall is set to block images coming from a site other than the main page. It's a sledgehammer approach to ad-blocking that often ends up blocking useful content. Your browser or firewall should have a method to enter accepted sites. Enter the site captchator.com as an accepted site, and you should be able to see the images. If for some reason you're unable to do that, there is a link below the Submit button that will set a temporary cookie on your PC. That cookie tells the evince system to host the image locally, which should satisfy your browser or firewall's restrictions. You must have your browser set to accept cookies. This is meant as a stop-gap solution, and the cookie will expire in 12 hours. The permanent solution is to properly configure your browser or firewall.
Why shouldn't I just use a checksum for validation?: Use of a checksum does have its place. Because of its relative simplicity, it's a good choice when the validation has to be done in the field. But for puzzles that can be solved at home, they fall well short of evince's capabilities. To start with, there are dozens of different checksum schemes. You have to make sure that both the puzzle owner and solver are using the same scheme, in the same manner, or false results will occur. And many simple checksums will not catch transposed digits. Checksum schemes like the double-add-double mod 10 (used in credit card numbers) which are designed to catch transpositions will still give a false positive 10% of the time. Finally, checksums can't be "fuzzy" - they only work with an exact set of coordinates. However, evince has none of these shortcomings.
Hey, you changed the input format. Will the links I've already created still work?: Based on user feedback, we removed the separate entry fields for the integer and fractional portions of the minutes. Instead, there is now a single field for the minutes that accepts a decimal point. This was changed to mirror the input fields of geocaching.com, which most people are already familiar with. This change is purely cosmetic. Any existing links will still work. Remember to use the period (.) as a decimal point, rather than the comma (,) used in parts of Europe, Africa, and elsewhere.
Why should I trust you with the answers to my puzzle cache? Can't you just look up the coordinates in the database?: No. With the exception of the horseshoes and atom bombs entries (see below), coordinates are never stored. Instead, a single hash value is calculated from the coordinates, and that hash value is stored in the database. The calculation is one-way. It's not possible to restore the original value from the hash. Also, to prevent what's called a "dictionary look-up", a secret 32 byte value is mixed with the coordinates before hashing. When someone wants to verify a coordinate, the same hash calculation is done with their entry, and if the hash values match, then the coordinates should be correct.
I accidently deleted the link from my cache page. Can you email it to me?: Nope. We don't ask what cache a link is created for, or who is creating it. This means you don't have to set up an account, or remember any passwords. This increases security, since there's no way to track a database record back to its cache. If you've deleted your link from your cache page, just generate a new one.
I've had to relocate my cache. How do I update the coordinates in evince?: You don't. If the coordinates have changed, just generate a new validation link, and replace the old link with the new one on your cache page. See the previous FAQ entry for the reasons why.
What's "horseshoes and atom bombs", and when should I select it?: There's an old saying, "close only counts in horseshoes and atom bombs". Likewise, there are cases when solving a puzzle cache, that close is the best you can ask for. Most puzzle caches will resolve to a single, exact set of coordinates. But a few types, because of the method(s) used to solve them, may not always return the exact same results. For example, caches that require a projection from a known point can give slightly different results based on the method used to calculate the projection. For cases such as these, we allow you to specify your coordinates, plus a distance in feet (the radius) from those coordinates that will be considered "good enough" to be correct. However, to do this it is necessary to store the actual coordinates in the database. There's unfortunately no way around it.
I added the code to my cache page, but I see the code instead of the image. What's wrong?: Cache page descriptions can be entered in one of two ways - plain-text, and HTML coded. To use images and links on your cache page, you have to use HTML code, and you have to check the check-box labeled The descriptions below are in HTML. If your cache page was originally entered in plain-text, you can use the html conversion utility to insert the proper HTML codes. Note that you need to perform the conversion before adding the evince code.