what's the difference with these hashes?

i know that Windows uses three kind of hashes: LM, NT and NTLM.

which format is more secure? I know that LM is the least secure of the three, but it is still supported for backwards compatability.

also, if i have an NTLM rainbow table, can it be used to crack either NT or LM hashes?

or if i have either a LM or NT only rainbow table, can it be used to crack an NTLM format password?

and for securing my own system, which is better?

Just disable LM hashes B)

Quote from http://support.microsoft.com/default.aspx/kb/299656

1. Start Registry Editor (Regedt32.exe).

2. Locate and then click the following key: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa
3. On the Edit menu, click Add Key, type NoLMHash, and then press ENTER.
4. Quit Registry Editor.
5. Restart the computer, and then change your password to make the setting active.

thanks for the tip, but what type of rainbow table is best to crack all three hashes?

is it the LM table, NT table or NTLM table? I like to know the best answer as generating these tables take up space and speed, so i'd like a rainbow table that covers all three.

fuser wrote: thanks for the tip, but what type of rainbow table is best to crack all three hashes?

is it the LM table, NT table or NTLM table? I like to know the best answer as generating these tables take up space and speed, so i'd like a rainbow table that covers all three.

The NTLM table would be best, but would take very long time to generate and use much HDD space. I'd recommend only using a LM table, since LM hashes are split into 2 pieces with 7 bytes in each which means you only have to make a table for 1-7 characters ;)

However if someone has disabled LM hashes (which is quite unlikely) you'll need a NT table instead.

ok, thanks.