Replaying and server side caching.
Jacques A. Vidrine
n+krb at nectar.cc
Fri Apr 11 13:21:44 EDT 2003
On Fri, Apr 11, 2003 at 09:41:22AM -0700, Nicolas Williams wrote:
> Though I suppose that it might be easier to mount a dictionary attack
> against an AS-REP's enc-part than against a pa-enc-timestamp. Is it?
No. They are both quite easy due to ASN.1 encoding regularities.
In the first 16 bytes of either, much of the content is known or
trivially recognizable. The PA-ENC-TIMESTAMP content is mostly known
except for perhaps the hour/minute/seconds part. For example,
x30 x0E xA0 x11 x18 x0F "20030411HHMMSSZ"
(with the slight wrinkle that there may be a pausec member that changes
the value of the 2nd octet).
Actual DER maybe be slightly different from the above due to sloppy
work on my part :-) but you see what I mean.
Jacques A. Vidrine <nectar at celabo.org> http://www.celabo.org/
NTT/Verio SME . FreeBSD UNIX . Heimdal Kerberos
jvidrine at verio.net . nectar at FreeBSD.org . nectar at kth.se
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