[saag] PKIX and related RFCs - definition of Key Packages

["Blumenthal, Uri - 0553 - MITLL" <[e-mail]>]

I confess that until now I never bothered actually looking with a critical eye at RFC 5958, 5208, 5915 and such – because the apps that presumably use them to interoperate, were already written by somebody else and (sorta ;) working.

 

Now, as I’m looking at extending those definitions to Post-Quantum algorithms and parameters, I’m seeing what appears weird to me.

 

A lot of the ASN.1 definitions seem to describe how to package private keys. Considering that interoperability in the majority of cases is about applications communicating “over the wire” using S/MIME, CMS, TLS or IKE key exchange, etc. – the predominant need appears to be exchanging public (not private) keys?

 

Yet the definitions invest in the details of the private keys, leaving the public key as “BIT STRING OPTIONAL”. Why is it so?

 

IMHO, first – PublicKey should be OCTET STRING (probably not OPTIONAL), probably CONTAINING {}. Then, each specific IETF-accepted algorithm should have its own definition of how to serialize its public key, maybe wrapping the result into an OCTET STRING (usually this is done to allow parser that doesn’t understand the format, to skip this field)… 

 

Is it too late to rectify? And if I’m missing something, could you enlighten me please? Am I barking at the wrong tree altogether? If so, where is the public key serialization described, if not here? And why not here?

 

Thank you! And apologies for the exhibited ignorance.

 

Here are some examples of what I’m talking about:

 

ECPrivateKey ::= SEQUENCE {

     version        INTEGER { ecPrivkeyVer1(1) } (ecPrivkeyVer1),

     privateKey     OCTET STRING,

     parameters [0] ECParameters {{ NamedCurve }} OPTIONAL,

     publicKey  [1] BIT STRING OPTIONAL

   }

 

OneAsymmetricKey ::= SEQUENCE {

     version                   Version,

     privateKeyAlgorithm       PrivateKeyAlgorithmIdentifier,

     privateKey                PrivateKey,

     attributes            [0] Attributes OPTIONAL,

     ...,

     [[2: publicKey        [1] PublicKey OPTIONAL ]],

     ...

   }

 

PublicKey ::= BIT STRING

                     -- Content varies based on type of key. The

                     -- algorithm identifier dictates the format of

                     -- the key.

--

Regards,

Uri Blumenthal                              Voice: [phone] 

Secure Resilient Systems and Technologies   Cell:  [phone]

MIT Lincoln Laboratory                      

244 Wood Street, Lexington, MA  02420-9108      

 

Web:     https://www.ll.mit.edu/biographies/uri-blumenthal

Root CA: https://www.ll.mit.edu/llrca2.pem

 

There are two ways to design a system. One is to make is so simple there are obviously no deficiencies.

The other is to make it so complex there are no obvious deficiencies.

                                                                                                                                     -  C. A. R. Hoare