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
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