Re: [ws-sx] Issue 014: Is the key agreement algorithm proposed inWS-Trust sound?

The key size can be set through the AlgorithmSuite assertion in 
SecurityPolicy.

Jiandong

Marc Goodner wrote:
> Assigned issue number 014.
> 
> Marc Goodner
> Technical Diplomat
> Microsoft Corporation
> Tel: (425) 703-1903
> Blog: http://spaces.msn.com/members/mrgoodner/ 
> 
> -----Original Message-----
> From: Prateek Mishra [mailto:] 
> Sent: Tuesday, January 24, 2006 2:35 PM
> To: 
> Subject: [ws-sx] New Issue: Is the key agreement algorithm proposed in
> WS-Trust sound?
> 
> Protocol:  ws-trust
> 
> 
>   <>Artifact:  spec
> 
>  
> 
> Type:
> 
> design
> 
>  
> 
> Title:
> 
> Is the key agreement algorithm proposed in WS-Trust sound?
> 
>  
> 
> Description:
> 
> <> Section 6.2.4 proposes the use of P_SHA-1 algorithm taken from rfc 
> 2246 (TLS 1.0) for implementing a key agreement protocol.
> However, key agreement in rfc 2246 involves a somewhat different 
> construction which uses P_SHA-1 only as a sub-component.
> 
> (1) Is there an analysis or other material available to support the use 
> of P_SHA-1 as proposed in WS-Trust?
> 
> (2) P_SHA-1 is an iterative method that could theoretically generate 
> keying material of unbounded size. It would seem that there would
> need to be some constraints on the sizes of Ent(req), Ent(resp) and the 
> computed key. For example, would Ent(req) and Ent(resp) be
> required to be at least 160 bits? And, if so, what then would be the 
> recommended size of the computed key?
> 
> 
> 
>  
> 
> Related issues:
> 
> 
>  
> 
> Proposed Resolution:
> 
> I dont have one. I am seeking further information from the editors of 
> the current specification draft.
>