The general reason in Microsoft environments is backwards compatibility. They have had a number of password hashing schemes over time, each getting better. Bu

The general reason in Microsoft environments is backwards compatibility. They have had a number of password hashing schemes over time, each getting better. But the password itself isn't sent in the clear over the wire so there is no way to upgrade the user account from one hash to another. The only time it can be done is when the user changes their password, and again that requires the authentication service getting the new password in the clear. Consequently they tend to store all supported hashes at once, and you are limited to the lowest common denominator. http://en.wikipedia.org/wiki/LM_hash http://en.wikipedia.org/wiki/LM_hash http://en.wikipedia.org/wiki/NTLM#NTLMv1 http://en.wikipedia.org/wiki/NTLM#NTLMv1 http://support.microsoft.com/kb/299656 http://support.microsoft.com/kb/299656