RE: [wss] Web Services Security Username Token Profile

["Ahmed, Zahid" <zahid.ahmed@commerceone.com>]

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