Re: [pkix] Strawman on EdDSA/Ed25519 for PKIX Certificate/CRLs

Bonjour,

Section 5: EdDSAParameters is an ENUMERATED with (for now) only one value:
"ed25519", which designates a signature algorithm and not a set of public
key parameters. I guess one might want to find "curve25519" and "curve448"
here. Since this type is used with a public key algorithm, naming it with a
signature algorithm might not be suited.

Section 5: the subjectPublicKey BIT STRING seems to contain an additional
OCTET STRING, which isn't necessary at this moment (however, since point
encoding hasn't been decided yet at CFRG, it may change).

Section 6: what is the rationale to define keyUsage values here? I'd drop
this section.

Section 7: signature parameters will be necessary and will be declared
either within the algorithm OID (as is done with ECDSA-with-*), within the
parameters data element, or both (as is done with RSASSA-PSS); right now,
Ed25519 is hardcoded to use SHA512, but you'll have to consider EdDSA with
other hash functions, or different curves (it's not yet decided which hash
function to use with curve448).
Section 7: signature encoding itself must also be defined (or referenced);
for ECDSA, it's a SEQUENCE of 2 INTEGERs; here, it seems that r and s are
concatenated, but it's stated nowhere (maybe draft-josefsson-eddsa-ed25519?)

Section 8: the example certificate doesn't use the EdDSAParameters type to
indicate the curve used.
Section 8: the example certificate doesn't follow section 7 (parameters
MUST be absent)

2015-06-15 22:10 GMT+02:00 Simon Josefsson <simon@josefsson.org>:

> Hi,
>
> I have updated the document a bit.  It appears likely that EdDSA will be
> usable with other parameters than Ed25519, so I made the EdDSA
> parameters an algorithm parameter rather than implied from the OID.
>
> https://tools.ietf.org/html/draft-josefsson-pkix-eddsa-01
>
> An (already outdated) example of an EdDSA X.509 certificate and EdDSA
> public-key is also included, so you can throw it at your ASN.1 parsers.
>
> /Simon
>
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-- 
Erwann.