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Subject: RE: [wss] Web Services Security Username Token Profile


Ron,

Please see previous e-mail as response to Gene. 


>So for me, the key form used with usernametoken based data origin 
>authentication is more a funtion of what the end system is capable 
>of doing, than it is what the processing model is. If the 
>authentiction interfaces of the end system do not make it
>possible for the signature validator to get access to either 
>the actual password value, or to acquire a password derived 
>key, then we are likley stuck with sending an encrypted
>password. Otherwise sending key derivation parameters, would 
>likley be better.

Thanks for this explanation. My take is that if end-point
WS-Security enabled application does not care to validate
signature but just validate the password (due to availability
of secure transport), then it would be useful to distinguish 
between the basic password token and its variant, the securely 
binded password token. This may help us w.r.t. interops
possibly.

thanks,
Zahid




-----Original Message-----
From: ronald monzillo [mailto:ronald.monzillo@sun.com]
Sent: Wednesday, January 29, 2003 1:57 PM
To: Ahmed, Zahid
Cc: 'Web Services Security'
Subject: Re: [wss] Web Services Security Username Token Profile


Zahid,

I don't understand your concern about using other than DSA and RSA keys 
as it
would seem to also preclude the Kerberos token binding.

All of our token profiles suggest that they be used (perhaps among other 
uses)
to convey a key to support a signing or encryption operation; most
notably to achieve data origin authentication in the presence of 
intermediaries.

If you are advocating another form of data origin authentication, not 
based on
signatures, then I would think you would still want to use the security 
token
to convey the key, and I think you would still need something to convey to
what parts of the message the data origin was bound. IMV, the SignedInfo
component of signature should be used for the latter purpose.

It seems to me that perhaps the only important use model for passwords 
is the case
where you need to get a password all the way through to some end system 
that doesn't accept anything else but a password, and you want to make 
sure that it is the only place that
will be able to see the password. Even in this case, you likely want to 
use the password
to sign the msg (as in with a signature)

So for me, the key form used with usernametoken based data origin 
authentication
is more a funtion of what the end system is capable of doing, than it is 
what the
processing model is. If the authentiction interfaces of the end system 
do not make it
possible for the signature validator to get access to either the actual 
password value, or
to acquire a password derived key, then we are likley stuck with sending 
an encrypted
password. Otherwise sending key derivation parameters, would likley be 
better.


Ron


Ahmed, Zahid wrote:

>Generally, I don't think it is a good idea to coerce Password tokens
>to behave like other types of tokens that require proof of possession
>or evidence of holding the (signing) key.
> 
>I do, however, appreciate the motivation of securely binding the
>Password token to a part of SOAP message such that we can
>protect the integrity of token association with the message indepedent
>of the transport protocol used to transmit the SOAP message.
>We can also argue that encryption of password is required
>independent of transport security. However, in practice, the SSL/TLS
>transport is sufficient in both of these problem domains.
> 
>I'm also concerned that we do not want to generate signature using
>PBE algorithm (using the Password in Password token) if it will imply
>not being compatible with W3C XML Signature which specifies use of
>DSA (required) and RSA algorithms (optional).
>
> 
>Perhaps we could consider this as new token profile, but keep the
>basic password token profile scope as is.
> 
>thanks,
>Zahid
>
>-----Original Message-----
>From: Gene Thurston [mailto:gthurston@amberpoint.com]
>Sent: Wednesday, January 29, 2003 12:10 PM
>To: 'Web Services Security'
>Subject: RE: [wss] Web Services Security Username Token Profile
>
>
>
>Colleagues,
>
> 
>
>[.......]
>
> 
>
>(General)  Discussion:  Overall, while I think that this token profile will
>be widely used (perhaps the first one to be widely used, since folks are
>generally familiar with, and have large databases of, username/password
>pairs), I see that its main weakness is the lack of binding the token to
the
>message "request" or "response" (that is, some part of the message body
>which represents what the username is "saying".  While it is true that
using
>a secure transport (such as HTTP over SSL) can provide this, there is an
>alternative approach, which in some sense fits in better with the overall
>WS-Security processing model of using signatures to provide this "binding".
>(Of course, signatures also provide evidence of the "claims" asserted by
the
>presence of various tokens.)  So, I think another profile here, surrounding
>the Username token goes something like this:
>
>*         Username token only carries the username.  (The implicit claim
>here is that the user named is the "sender", I suppose.)
>
>*         A signature is included using a PBE algorithm, and signs that
>portion of the body that the "sender" is stating ... typically, the message
>Body.
>
>*         The signature may also sign the timestamp header (described in
>Appendix A of the Web Services Security: SOAP Message Security
>specification) to combat replay attacks.  (Side note:  Shouldn't we add a
>general <wsu:Nonce> element as a header which can be used by *all* types of
>tokens?)
>
>*         The <ds:KeyInfo> element of the signature will use a
><wsse:SecurityTokenReference> to the Username token.
>
>*         The "key" associated with that token will be generated based on
>the mutually shared secret password (or equivalent) using a standard PBE
>algorithm.
>
>It seems to me that the user interaction in this scenario will still look
>the same:  Need a username and password.  But, that the processing model is
>now a lot more consistent with the other kinds of security tokens we expect
>to see.  Basically, while I don't believe we have come right out and said
>so, I think *all* of the token types we have considered can be thought of
as
>"Key Holders" ... either a key is explicitly embedded in the token (ala,
>X.509 certificates), or a key is somehow implicitly represented or can be
>generated.  Am I way off base here?
>
>
>
>
>
>That's about it.  Thanks for playing!
>
>
>
>- Gene Thurston -
>
>AmberPoint, Inc.
>
>
>
>
>
>
>
>
>
>-----Original Message-----
>From: Anthony Nadalin [mailto:drsecure@us.ibm.com] 
>Sent: Tuesday, January 28, 2003 6:33 AM
>To: Web Services Security
>Subject: [wss] Web Services Security Username Token Profile
>
>
>
>
>
>
>
>
>
>
>
>Here is the UsernameToken update that Phil created it was edited to be in
>
>line with the WSS-Core-09 update.
>
>(See attached file: WSS-Username-11.pdf)
>
>
>
>Anthony Nadalin | work 512.436.9568 | cell 512.289.4122
>
>
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