Re: [dss] JPMorgan/RSA message

[Trevor Perrin <trevp@trevp.net>]

At 11:59 AM 10/9/2004 -0400, Glenn.Benson@chase.com wrote:

>Trevor,
>
>Thanks for your questions.  I will answer the first two questions in this
>e-mail.  I will send a subsequent e-mail answering your second two
>questions about JPMorgan's and RSA's ideas about how PSTP and OTP could fit
>into DSS.
[...]

Thanks Glenn,

My understanding is something roughly like:

Ke : RSA public key, used to encrypt K1 and K2
K1 : symmetric key, used to encrypt OTP
K2 : symmetric key, used to MAC document

PSTP Signature = Enc(Ke,K1|K2) | Enc(K1,OTP) | Mac(K2,Data)


I'm looking forward to your thoughts on DSS integration.


Trevor



>Glenn
>
>PSTP Technical Executive Summary
>The Portable Security Transaction Protocol (PSTP) is an XMLDSIG-compliant
>vehicle used for signing documents with One-Time Passwords (OTP) such as
>RSA SecurID.   A motivation of PSTP is to address some logistic impediments
>in the Public Key Infrastructure (PKI).  The PKI provides good security
>when it adequately protects its private keying material.  Hardware Security
>Modules (HSMs) address this issue in servers that reside in protected data
>centers; and the client may address the issue using smart cards, USB
>tokens, or HSMs.  However, some clients may prohibit these hardware
>solutions due to the necessary electronic conduit between the private
>keying material, and the data being subject to the digital signature.
>
>The technical issue addressed by PSTP is that an OTP does not bind the
>private authentication credential to the data being signed.  PSTP envelopes
>the OTP and the target data into a single cryptographic structure.  This
>structure cryptographically fuses its elements into a single, atomic PSTP
>signature.
>
>A PSTP signature has three components:
>-   The Authentication Component transfers authentication credentials from
>the client to the recipient.  A symmetrically keyed algorithm protects the
>confidentiality of the authentication component.
>-  The Message Integrity Component is an HMAC computed over the target
>dataset.
>-  The Key Management Component communicates the keys used for the other
>two components securely, while binding the two keys together.   PSTP
>specifies RSA-OAEP and elliptical curve technology to bind the
>authentication component and message integrity component keys into an
>atomic structure.
>
>PSTP focuses on message authenticity which (i) authenticates the sender,
>(ii) protects the integrity of the communication, and (iii) protects
>against replay attacks.  The XMLDSIG-compliant structure provides
>compatibility with standards such as DSS.
>
>
>
> 
>
>                       Trevor 
> Perrin 
>
>                       <trevp@trevp.net>        To: 
> <dss@lists.oasis-open.org>
>                                                cc: 
>
>                       10/07/2004 03:46         Subject:  Re: [dss] 
> JPMorgan/RSA message
>                       AM 
>
> 
>
> 
>
>
>
>
>
>
>Hi Glenn,
>
>A few things about PSTP and its relation to DSS were unclear to me:
>
>   - In the "Document Signature" case, a signature is performed on the
>client side.  Is this a public-key signature?  How is the one-time-password
>
>used?
>
>   - In the "Web Services Authentication" case, it says "the client executes
>
>a PSTP signature".  What is a PSTP signature and how is it executed?
>
>   - Where would the DSS sign or verify protocols fit?  I'm guessing you
>could use DSS to produce a "PSTP signature" based on the client
>authenticating to a DSS server with a one-time-password?
>
>   - You talk about DSS in the context of an in-line validation server,
>which validates a signature and then marks the document so that downstream
>parties know it was validated.  DSS is a request/response protocol, so I'm
>curious how you would use it here.  Would the in-line validation server
>call out to a DSS server?  Or would the inline DSS server mark the document
>
>with a DSS <VerifyResponse> element, so that downstream parties could
>process it as if they had made a <VerifyRequest>?
>
>
>Trevor
>
>
>
>At 05:25 PM 10/4/2004 +0200, Juan Carlos Cruellas wrote:
> >Dear all,
> >
> >I have received the message below sent by Glen asking
> >me to forward it to the group.
> >
> >Regards
> >
> >Juan Carlos.
> >
> >-------- Original Message --------
> >Subject:        failure notice
> >Date:   Mon, 4 Oct 2004 10:05:33 -0400
> >From:   Glenn.Benson@chase.com
> >To:     administration@lists.oasis-open.org
> >CC:     cruellas@ac.upc.es
> >
> >
> >
> >Administrator:
> >
> >My e-mail would not forward.  Please forward to the dss list server.
> >
> >Thank you,
> >
> >Glenn Benson
> >
> >
> >
> >Standardization Vision
> >
> >Glenn Benson, JPMorgan
> >Burt Kaliski, RSA Security
> >
> >
> >XMLDSIG
> >The Portable Security Transaction Protocol (PSTP) is a digital signature
> >mechanism that leverages one-time password technology.  The PSTP
> >specification is XMLDSIG-compliant.  While one may employ either PSTP or
> >PKI in any XMLDSIG scenario, PSTP has some advantages in interactive
> >environments; and PKI has some advantages in non-interactive environments.
> >In an interactive environment, PSTP allows a user to consult a secured,
> >two-factor authentication token such as RSA SecurID without installing
> >hardware, customized software, or device drivers on client machines.  One
> >may employ PSTP in many different use cases.  As examples, we depict two
> >below.
> >
> >Document Signature:  A user obtains a document, transaction data, or other
> >information and applies a signature.  The user consults a disconnected
> >one-time password device, and enters the current value into an Applet or
> >ActiveX control through a browser interface.  The Applet or ActiveX
>control
> >cryptographically processes the user's data in accordance to the PSTP
> >specification, and applies the signature.  The user uploads the signed
> >document to a server for verification.
> >
> >Web Services Authentication:  SAML injection is a technique whereby a
> >client makes a request, which may include proprietary authentication
> >material.  A proxy intercepts the request prior to the request's arrival
>at
> >the destination.  The proxy interacts with an authentication server in
> >order to validate the authentication credential which the proxy extracts
> >from the request.  Subsequently, the proxy injects a SAML token for
> >subsequent consumption at the destination.
> >
> >One may deploy SAML injection at either the server or the client.  The
> >advantage of server-based SAML injection is that it does not require
> >client-based software.  However, server-based SAML injection does not bind
> >authentication credentials with the payload until after the payload
> >traverses the network.  The advantage of client-based SAML injection is
> >that it binds data to authentication material at the client's location.
> >However, the disadvantage is that it requires a  session-based service
>that
> >operates on the client's machine.  This service initiates an out-of-band
> >authentication invocation which authenticates credentials, and then
>obtains
> >a SAML token for injection into subsequent packets.  PSTP provides an
> >alternative to client-based SAML injection.  At the client location, the
> >client executes a PSTP signature over a SOAP payload.  The client inserts
> >the PSTP signature into the message under the auspices of WS-Security.
>The
> >client uploads to a server-based SAML injection service.  The service
> >validates the PSTP signature, and then injects a SAML assertion into the
> >payload.  The service forwards the modified payload to the destination.
> >The destination leverages a SAML-aware web services Single Sign-on
> >mechanism to authenticate the payload.
> >
> >DSS
> >One signature validation use case deploys the signature validation server
> >in-line between the client and the application, as in the case of the
> >PSTP-aware SAML injection proxy described above.  First, the client sends
>a
> >message that contains signed information.  The in-line signature
>validation
> >server receives the message and performs the requested validation,
> >potentially via a DSS signature validation service.  The signature
> >validation server then injects a token, which binds the document and/or
> >signature to a validation result code and forwards the binding to a
> >downstream application.  The application validates the binding and accepts
> >the signed information.  Presumably, the application requires a simpler
> >utility for validating the binding than would be required for signature
> >validation.
> >
> >A second aspect of DSS is that it includes a mechanism by which the client
> >may submit a request for a signature. There are various ways to bind
>strong
> >client authentication to such a request. This could be done within the
> >security binding, e.g., via TLS. The current DSS specification supports
> >X.509 mutual authentication (Sec. 6.3.2) but not specifically one-time
> >password authentication for the client; such authentication, e.g., over
> >SASL, could potentially be added.
> >
> >Alternatively, the binding could be done within the DSS request itself
>(for
> >instance, in <OptionalInputs>). This has the advantage of providing
> >cryptographic consequential evidence of the signer's intent within the DSS
> >request. The DSS request itself could contain a one-time password. The
> >password could also be combined with the request in various ways, e.g., by
> >hashing. PSTP is one example of such a combination that provides a strong
> >cryptographic coupling.
> >
> >
> >-
> >
> >
> >
> >
> >
> >
> >
> >
> >To unsubscribe from this mailing list (and be removed from the roster of
> >the OASIS TC), go to
> >http://www.oasis-open.org/apps/org/workgroup/dss/members/leave_workgroup. 
> php.
>
>
>
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>.