Re: [Trans] [trans] #79 (rfc6962-bis): Precertificate signaturemustbe over something other than just the TBSCertificate

[Rob Stradling <[e-mail]>]

On 12/06/15 16:27, Erwann Abalea wrote:
<snip>
> If the eContentType is set to id-data, the CMS producer can omit the
> SignedAttributes, the signature is performed over the eContent (which
> contains the TBSCertificate), and the resulting signed precertificate
> can be manipulated to become a valid certificate:
>    - take the TBSCertificate and the signature from the CMS/precertificate,
>    - build a SEQUENCE containing the TBSCertificate, a properly
> formatted SignatureAlgorithm, and the signature (reencode it from OCTET
> STRING to BIT STRING)
>    - you have a valid certificate

Indeed.

> To avoid this, just make sure that the TBD in the current rfc6962-bis is
> NOT id-data. Or require the presence of the SignedAttributes.

Ben, do you want to allocate an OID from the Google arc for this?

<snip>
>                After discussion with Rob, core point is that the CMS
>             signature is
>             not an X509 signature.
>
>                Fixed at https://github.com/google/certificate-transparency-
>                rfcs/commit/546e6e9451186e96ddd7b54ca02f17c8d86f951e.
>
> This commit has nothing to do with the ticket ;)

It was a series of several commits.  That was the final one.

Click the link just to the right of "1 parent".  Then do the same again, 
and you should arrive at...
https://github.com/google/certificate-transparency-rfcs/commit/c62061213c5085cf4d0f266dc8aa2c803bcf4c8f

-- 
Rob Stradling
Senior Research & Development Scientist
COMODO - Creating Trust Online
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