CrackStation.net's Lookup Tables

Introduction

There are three components to this system:

1. The indexing PHP script (createidx.php), which takes a wordlist and builds a lookup table index for a hash function and the words in the list.

2. The indexing sorter program (sortidx.c), which sorts an index created by the indexing script, so that the lookup script can use a binary search on the index to crack hashes.

3. The lookup script (LookupTable.php), which uses the wordlist and index to crack hashes.

The system is split up like this because PHP provides easy access to many different types of hash functions, but is too slow to sort large indexes in a reasonable amount of time. We are planning to re-write components #1 and #3 in C or C++.

Building and Testing

The PHP scripts to not need to be built. To build the C programs, run make.

To run the tests, just run make test, and then clean up the files the tests created with make testclean.

Indexing a Dictionary

Suppose you have a password dictionary in the file words.txt and you would like to index it for MD5 and SHA1 cracking.

First, create the MD5 and SHA1 indexes:

$ php createidx.php md5 words.txt words-md5.idx
$ php createidx.php sha1 words.txt words-sha1.idx

Next, use the sortidx program to sort the indexes:

$ ./sortidx -r 256 words-md5.idx
$ ./sortidx -r 256 words-sha256.idx

The -r parameter is the maximum amount of memory sortidx is allowed to use in MiB. The more memory you let it use, the faster it will go. Give it as much as your system will allow.

You now have everything you need to crack MD5 and SHA1 hashes quickly.

Cracking Hashes

Once you have generated and sorted the index, you can use the LookupTable class to crack hashes. See test/test.php for an example of how to use it.

Adding Words

Once a wordlist has been indexed, you can not modify the wordlist file without breaking the indexes. Appending to the wordlist is safe in that it will not break the indexes, but the words you append won't be indexed, unless you re-generate the index. There is currently no way to add words to an index without re-generating the entire index.