On 27 Jun 2006, at 7:17 AM, Werner Koch wrote:
I can't comment on TLS specific things but here are a few minor
OpenPGP keys (sometimes called OpenPGP certificates), provide
security services for electronic communications. They are widely
deployed, especially in electronic mail applications, provide
key authentication services, allow distributed key management
be used with a non hierarchical trust model called the "web of
Because OpenPGP does not define any trust model, a wording like
... and allows the use in non hierarchical trust models, for
example the "Web of Trust"[WOT].
seems to better to me.
The important thing is that trust models are not part of OpenPGP.
I think it should also say, "OpenPGP certificates (often called
OpenPGP keys), ..." for reasons I'll state more fully after my
comments on Werner's comments.
2.3. Server Certificate
DHE_RSA RSA public key which can be used for
Shouldn't this say: "RSA public key which can be used for
authentication"? Recall that OpenPGP features a key flag to indicate
an authentication key (0x20).
Yes, it should.
3. Security Considerations
As with X.509 ASN.1 formatted keys, OpenPGP keys need specialized
parsers. Care must be taken to make those parsers safe against
maliciously modified keys, that could cause arbitrary code
That is superfluous as this is (or well, should) be standard
programming practise. It is in no way special to TLS or OpenPGP.
I concur. It might as well have another paragraph as well that says:
This RFC specifies the use of data. Improper use of data can cause
arbitrary code execution. Care must be taken to prevent this.
I think that paragraph can go.
There is one other issue that I think should be cleaned up. It
concerns the use of the words, "key" and "certificate." The term "PGP
Key" was invented by Whit Diffie, and has a number of desirable
characteristics. It's one syllable, it's an easy word to say.
However, "PGP Keys" are in fact certificates that contain at least
one key and at least one certification.
In RFC2440 and beyond, we have used the colloquial term "key" but I
think in this document the more precise term "certificate" is called
for. Strictly speaking, the objects that TLS is using in this draft
is a PGP Certificate with a Public Key Packet (tag 6) or Public
Subkey Packet (tag 14) that is enabled for authentication implicitly
This is why a little bit of over-precision is called for. I might
present you with a single-key OpenPGP certificate that is enabled for
authentication with a key flags subpacket. But I might also present
you with an OpenPGP certificate that has a subkey with no key flags,
which would also be reasonable.
So I recommend changing "OpenPGP key" or "OpenPGP public key" to
"OpenPGP certificate" throughout the document. It might be good to
point out the fact that it can be a subkey. Minimally, one could
change the text in 2.3:
An OpenPGP public key appearing in the Certificate message will be
sent using the binary OpenPGP format. The term public key is
describe a composition of OpenPGP packets to form a block of data
which contains all information needed by the peer. This includes
public key packets, user ID packets and all the fields described in
section 10.1 of [OpenPGP].
An OpenPGP certificate appearing in the Certificate message will
be sent using the binary OpenPGP format. The term certificate is
used to describe a composition of OpenPGP packets to form a block
of data which contains all information needed by the peer. This
includes public key packets, subkey packets, user ID packets and
all the fields described in section 10.1 of [OpenPGP].
That would work just fine and would preserve the virtue of terseness
that the present draft has.