Ophcrack is a free open source program that cracks Windows passwords by using LM hashes through rainbow tables. The program includes the ability to import the hashes from a variety of formats, including dumping directly from the SAM files of Windows. On most computers, ophcrack can crack most passwords within a few minutes.Rainbow tables for LM hashes of alphanumeric passwords are provided for free by the developers. By default, ophcrack is bundled with tables that allows it to crack passwords no longer than 14 characters using only alphanumeric characters. Available for free download are two Windows XP tables, one small and one fast, and one Windows Vista table.Ophcrack is also available as Live CD distributions which automate the retrieval, decryption, and cracking of passwords from a Windows system. One Live CD distribution is available for Windows XP and lower, as well as another for Windows Vista and Windows 7.