Subject: [therightkey] draft-laurie-pki-sunlight-02

From: Chris Richardson <[email-masked]>
Date: Thu, 15 Nov 2012 02:09:53 +0000

I have a few questions and comments on this document:

A general comment: What should a log do if it receives multiple
submissions of the same certificate?  It MUST detect and reject
duplicates?  SHOULD detect?  What if it receives a certificate
containing an embedded SCT from itself?  MUST/SHOULD/MAY reject?

Section 1.1 fixes the hash algorithm as SHA-256.  It makes no mention
of acceptable digital signature algorithms.
http://www.certificate-transparency.org/sizes indicates the thinking
is ECC.  Is RSA an acceptable signature algorithm?

Section 2.1: Shouldn't Version be covered by the signature in a
SignedCertificateTimestamp?  I'd think it would be beneficial to be
able to verify that the signature was intended for the same version as
is claimed in the unsigned portion.

Section 2.2 (minor edit): upon first read, the units of old_tree_size
wasn't clear (leaf count?  bytes?)  The description of tree_size is
explicit on the units ("number of entries").  I would appreciate it if
old_tree_size had similar text.

Section 2.3 (minor edit): the last bullet uses the term
tree_signature, when the rest of the text uses tree_head_signature.

Regards,
Chris

---

From: Ben Laurie <[email-masked]>
Date: Thu, 15 Nov 2012 14:32:25 +0000

> containing an embedded SCT from itself?  MUST/SHOULD/MAY reject?

MAY return the same SCT as last time - this is already fixed in the
next version (which I couldn't submit coz of cutoff dates).

> is ECC.  Is RSA an acceptable signature algorithm?

Yes, but obviously expensive, since a certificate should usually
contain more than one SCT.

> is claimed in the unsigned portion.

Yes, this is already fixed, also.

> old_tree_size had similar text.

OK.

> tree_signature, when the rest of the text uses tree_head_signature.

Oops.

I'm travelling this week, but will try to get an update out next week.

>
> Regards,
> Chris
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