Re: [Teep] OTrP Signature Security issue

On 2018-11-21 10:08, Hannes Tschofenig wrote:
> Hi Anders,
> 
> Thanks for raising this point.

For completeness I should probably mention that there is no major problem i OTrP since the object "sub-identifier" is signed.

It does however require an additional validation step since a "TAInformation" object MUST be followed by its signed "TAInformationTBS" counterpart.

In both JWS and COSE the original message is "destroyed" (converted into an alien format) and must be recreated before it can be acted upon.

Anders

> 
> I have been wondering whether a JSON encoding is the best choice for TEEP since web developers shouldn't actually be exposed to any of it.
> 
> Hence, my question to you is whether you have looked into COSE as well and whether your assessment would be different.
> 
> Ciao
> Hannes
> 
> -----Original Message-----
> From: TEEP <teep-bounces@ietf.org> On Behalf Of Anders Rundgren
> Sent: Tuesday, November 20, 2018 9:57 PM
> To: teep@ietf.org
> Subject: [Teep] OTrP Signature Security issue
> 
> The following is a for brevity simplified version of the OTrP signature scheme.  That OTrP rather uses the JSON serialized version of JWS has no security advantages (or disadvantages) over the JWS compact notation shown here:
> {
>      "carObject":  "eyetc.eyetc.xyxetc"
> }
> 
> Since "carObject" isn't signed, you can replace it with anything else and the signature will still validate.
> 
> 
> Using detached JWS combined with JCS [1,2] you sign the entire JSON object as well as getting the "payload" in clear:
> {
>      "carObject": {
>         "brand":  "Ferrari",
>         "horsePower":  "450",
>         "weight":  "2357kg"
>      },
>      "signature": "eyetc..xyect"
> }
> 
> thanx,
> Anders
> 
> 1] https://tools.ietf.org/html/draft-rundgren-json-canonicalization-scheme-01
> 2] https://mobilepki.org/jws-jcs
> 
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