Re: TGS revisited

[Simon Josefsson]

Elrond <address@hidden> writes:

> shishi-client:
...
> (+)                       Kvno: 1

This could be the problem, from your earlier logs, I think your
current kvno is 2.  It seems shishi hard code the authenticator
checksum kvno to 1, which is bad.  I've fixed this in CVS, and I think
the daily Debian packages has it.  Could you re-try?

shishi -v -v -v should display the same information as ethereal does,
only in a different format, so those logs should be sufficient.
However, when comparing heimdal output with shishi output, etherreal
seems very useful (especially when it decrypts messages too).

>                                   Checksum
>>>>>>>>                                        Type: Unknown (65398)
>                                       checksum: 
> C005E2E3616E85117D7BF005696E386F
...
>                                   Checksum
>>>>>>>>                                        Type: md5 (7)
>                                       checksum: 
> C552A4D8830301F555840CAC9D667EC0

This is more interesting, 65398 is -138 which is HMAC-RC4.  It may be
that w2k3 doesn't use the HMAC-RC4 scheme, but rather require MD5?

You don't really need the extra protection from HMAC-RC4 in the
checksum, because it is encrypted, so MD5 would have be sufficient.
Although I'd rather not use MD5 at all.

It could also be that the HMAC-RC4 implementation in shishi is buggy,
but at least it interop with heimdal:

address@hidden:~/src/shishi/src$ ./shishi -E arcfour-hmac address@hidden
Enter password for address@hidden':

address@hidden:
Authtime:       Tue Apr 25 13:39:33 2006
Endtime:        Tue Apr 25 21:39:32 2006
Server:         krbtgt/DOPIO.JOSEFSSON.ORG key arcfour-hmac (23)
Ticket key:     arcfour-hmac (23) protected by arcfour-hmac (23)
Ticket flags:   INITIAL PREAUTHENT (1536)
address@hidden:~/src/shishi/src$ ./shishi -E arcfour-hmac address@hidden 
host/latte
libshishi: warning: KDC bug: Reply encrypted using wrong key.
address@hidden:
Authtime:       Tue Apr 25 13:39:33 2006
Starttime:      Tue Apr 25 13:39:37 2006
Endtime:        Tue Apr 25 21:39:32 2006
Server:         host/latte key arcfour-hmac (23)
Ticket key:     arcfour-hmac (23) protected by arcfour-hmac (23)
Ticket flags:   PREAUTHENT TRANSITEDPOLICYCHECKED (5120)
address@hidden:~/src/shishi/src$

Which, if used with -v -v -v says it is using the -138 cksumtype:

  name:cksum  type:SEQUENCE
    name:cksumtype  type:INTEGER  value:0xff76
    name:checksum  type:OCT_STR  value:5a64fa14f5e035b9e12e4985df2b9356

Maybe w2k3 wants a MD5 checksum type there, instead of HMAC-RC4?

I manually changed it to 7 (see last part of lib/crypto-rc4.c, it
specifies the "default" checksum algorithm for each encryption type)
and it worked fine against heimdal.

  name:cksum  type:SEQUENCE
    name:cksumtype  type:INTEGER  value:0x07
    name:checksum  type:OCT_STR  value:c35e52d48d5fb097822c1076492bf439

If the kvno change above doesn't solve this, I'll try to make this
configurable somehow.

Thanks,
Simon