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Re: SSL not secure for WS??

From: Michael Hanson <hanson@reactivity.com>
Date: Fri, 04 Mar 2005 09:31:18 -0800
Message-ID: <42289B66.7000200@reactivity.com>
To: daniela.claro@eseo.fr
CC: www-ws@w3.org
Hello, Daniela -

SSL is sufficient for point-to-point web service connections; it 
provides authentication, integrity protection, confidentiality, and 
resistance to replay attacks.  The typical "server certificate only" 
configuration of SSL may be insufficient --in a high-value web service 
interaction you would frequently want to use a client certificate (a 
so-called "bilateral certificate exchange") to authenticate the client 
to the server.

When a web service intermediary (such as the Service Gateway made by my 
company, Reactivity), enters the picture, SSL is no longer sufficient.  
An intermediary such as our Gateway performs tasks like validation, 
verification of digital signatures, encryption or decryption, 
transformation, logging, and routing.  For all of these tasks, we 
require access to the unencrypted bytes of the message content, which 
means that we need to act as an SSL endpoint.  We can't just forward the 
SSL bytes onward because we do not have access to the private key of the 
client, so we either have to start a new SSL session with our own 
private key, or use non-SSL-based technologies for our cryptographic 

The WS-Security protocol provides mechanisms for authentication (SAML, 
WS Username), integrity protection (XML Signature), confidentiality (XML 
Encryption), and replay (through a variety of techniques).  These 
mechanisms all work by modifying the SOAP envelope (typically by adding 
more Headers, though Encryption also modifies Body elements). 

WS-Security-based techniques have the additional advantage of 
persistence.  An SSL session is ephemeral -- the guarantees of 
confidentiality and integrity apply only to bytes moving through the 
encrypted tunnel.  An encrypted or signed SOAP envelope can be sent to a 
message bus, stored on disk or inserted to a database, and will remain 
secure as long as the private keys used in its construction are kept 
secret.  In our product, for example, we write selected messages into a 
signed message log, which means that we have a tamper-evident store of 
secure content, which can help our customers satisfy regulatory and 
auditing requirements.

I hope that helps!  If you need more information, we have several white 
papers available here:


Michael Hanson
Chief Architect, Reactivity
Daniela CLARO wrote:

> Hi all,
>  Could anyone please explain me, why SSL is not secure for web 
> services? Moreover, what is exactly the "intermediaries" that could 
> exist between a web service connection that SSL can not garantee tthe 
> security anymore?
> Thank you very much,
> Daniela
Received on Saturday, 5 March 2005 04:55:33 UTC

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