Security impact of removing timestamp check in rd_rep()

Andrew Bartlett abartlet at
Mon May 16 04:07:19 GMT 2005

On Sun, 2005-05-15 at 17:04 -0400, Sam Hartman wrote:
> >>>>> "Luke" == Luke Howard <lukeh at PADL.COM> writes:
>     Luke> You actually want to check that they are different, to avoid
>     Luke> replay attacks.
> But you need to store all the timestamps you have seen in an allowable
> window.
> Really, I don't understand why you use a timestamp in a three-leg
> protocol.  It seems like you want to have a challenge in the second
> leg copied back in the third leg encrypted in a per-session key.
> However it sounds like DCE did not do this.

I think the sequence number is used for this.  It appears from the way
Microsoft implements their server, that they don't check the timestamps.

Now to figure out how to tell the krb5 layer that this is a DCE_STYLE
third leg...

Andrew Bartlett
Andrew Bartlett                      
Authentication Developer, Samba Team 
Student Network Administrator, Hawker College
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