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Re: MD5 To Be Considered Harmful Someday



On Wed, 8 Dec 2004, Dan Kaminsky wrote:

Can't we just truncate the password to 8 characters like in the old days
before doing the MD5 hash? It will greatly reduce the chance of a collision.
In fact, I am not even sure my systems don't do this already.

Actually, this greatly increases the chance of a collision. 123456789 will collide with 123456780.

I was talking about limiting the input, not the output. I assumed it would
be more difficult to find a collision when there are less degrees of freedom
in the input.

What I realised after my mail though, is that it is probably pretty easy to
prebuild a dictionary of all 8 character combinations and their MD5 sums.

Paul