MD4 checksum fix

jw schultz jw at
Tue Apr 1 09:35:24 EST 2003

On Tue, Jan 28, 2003 at 11:22:14PM -0800, Craig Barratt wrote:
> And I have several things I would like to work on and submit:
>  - Fix the MD4 block and file checksums to comply with the rfc
>    (currently MD4 is wrong for blocks of size 64*n, or files
>    longer than 512MB).
>  - Adaptive first pass checksum lengths: use 3 or more bytes of the MD4
>    block checksum for big files (instead of 2).  This is to avoid almost
>    certain first pass failures on very large files.  (The block-size is
>    already adaptive, increasing up to 16K for large files.)
> Except for the last, all these items were discussed in this group over
> the last few months.  The first two items and last item require a bump
> in the protocol number, so I would like to include all of them together.
> But before I work on these I would like to make sure there is interest
> in including them.

I've not heard from you on the adaptive checksum length patch.
I shall be committing it shortly subject to objections or
further discussion.

I would like to see the MD4 checksums fixed as well.  We are
very close to the upper limit on protocol versions for
deployed versions of rsync.  Therefore, i would like to
minimize protocol increments for a while.  In any other
circumstance i wouldn't suggest doing so but i think it
would be a good idea to integrate these two fixes in one
protocol bump.

If you, or someone else, has the fix for the MD4 sums handy
i would be glad to coordinate in implementing both sets of
patches at about the same time.  If you want to send it to
me, that would be fine.  I can also hold off for a short
while for the MD4 sum patch to get some testing.

	J.W. Schultz            Pegasystems Technologies
	email address:		jw at

		Remember Cernan and Schmitt

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