x.509v3 publickeys and signatures

["Joseph Galbraith" <galb-list%vandyke.com@localhost>]

In the transport draft, Section 4.6, we specify that
public keys are, in general encoded as:

     string   certificate or public key format identifier
     byte[n]  key/certificate data

However, the sections on x.509 are less clear.  And in fact,
SSH Communications current x.509 implementation omits the
string, including only the certificate data -- although
the string is included when sending signatures.

I would suggest we include the following text in section
documenting "x509v3-sign-rsa":

The "x509v3-sign-rsa" key format has the following specific encoding:

     string    "x509v3-sign-rsa"
     byte[n]   x.509v3 compatible der encoded certificate data

The resulting signature is encoded as follows:

     string    "x509v3-sign-rsa"
     string    rsa_signature_blob


Variants to this go in the other x.509 sections as appropriate.

In addition, I would suggest that we note that signatures
made with x509v3-sign-rsa keys MUST use the SHA-1 hash, and
be done using PKCS1.

Joseph Galbraith
galb-list%vandyke.com@localhost