GeoCaching Tool

Reconstruct lock code from MD5 Hash code

We have encountered some Mystery caches where the CO has provided a so called "MD5 Hash" of a lock code. In the past, MD5 hashing used to be a popular way to encrypt passwords. Due to the fact that the algorythm is flawed, it is not used for that purpose anymore.

The goal is to reverse the hashing mechanism to get the original code. Unfortunately, there is no way to do this (which makes sense, otherwise a hacker could restore a password that has been hashed by calling the 'unhash' function). The only way to solve this, is to take every possible value and create the MD5 hash for it, until you get a match with the hash provided.

Again, if that were easy, it would be easy for a hacker to find the original value. As we know the code we are looking for, is for a lock, there are much less possible values than for passwords: only digits.
To make life easy for you, I have written a script that does the hard work for you. All you need is to enter the MD5 hash and click the "Decrypt" button. If there's a match with any code of 6 digits (any code from 0 to 999999 and that includes codes like 0, 01, 0001, 00001, you get the point), it will display the matching code.

Some CO's have made it a bit harder by including a bit of text before the actual code before they made the hash. I know of one case where they included "Lock code: " befor the numer. If they did, they will mention this in their description. You can enter that text in the optional "prefix" field, enter the MD5 hash and hit "Decrypt".

Prefix (optional)

MD5 Hash code

Create MD5 Hash

Should you want to create an MD5 Hash, use the form below:

Prefix (optional)


















The JavaScript MD5 script is released under the MIT license.